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The validity of intracerebral hemorrhage diagnoses in the Danish Patient Registry and the Danish Stroke RegistryStine Munk Hald,1,2 email: stine.munk.hald@rsyd.dkChristine Kring Sloth,1 email: christine.kring.sloth@rsyd.dkMikkel Agger,1 email: mikkelagger@Maria Therese Schelde-Olesen,1 email: maria.therese.schelde-olesen2@rsyd.dkMiriam H?jholt,1 email: mihoejholt@Mette Hasle,1 email: metteravn13@Helle Bogetofte,1 email: helle.bogetofte.barnkob@rsyd.dkIda Olesrud,1 email: ida.olesrud@rsyd.dkStefanie Binzer,3 email: stefanie.binzer@rsyd.dkCharlotte Madsen,1 email: charlotte.milholdt.madsen@rsyd.dkWilly Krone,4 email: willy.krone@rsyd.dkLuis Alberto García Rodríguez,5 email: lagarcia@ceife.esRustam Al-Shahi Salman,6 email: rustam.al-shahi@ed.ac.ukJesper Hallas,7 email: jhallas@health.sdu.dkDavid Gaist1,2,8 email: dgaist@health.sdu.dk1Department of Neurology, Odense University Hospital, Odense, Denmark2Department of Clinical Research, Neurology Research Unit, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark3Department of Neurology, Lillebaelt?Hospital, Kolding, Denmark4Department of Radiology, Odense University Hospital, Odense, Denmark5Centro Espa?ol Investigación Farmacoepidemiológica (CEIFE), Madrid, Spain6Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom7Clinical Pharmacology and Pharmacy, Department of Public Health, University of Southern Denmark, Odense, Denmark8Odense Patient data Explorative Network (OPEN), Odense University Hospital, Odense, DenmarkCorrespondence: David GaistDept. Neurology, Odense University Hospital, J.B. Winsl?wsvej 4, 5000 Odense C, DenmarkTel +45 65412485Fax +45 65413389Email dgaist@health.sdu.dkORIGINAL RESEARCHShort running header: Validity of intracerebral hemorrhage diagnosis in two nationwide Danish registriesStine Munk Hald et alThe validity of intracerebral hemorrhage diagnoses in the Danish Patient Registry and the Danish Stroke RegistryStine Munk Hald,1,2 Christine Kring Sloth,1 Mikkel Agger,1 Maria Therese Schelde-Olesen,1 Miriam H?jholt,1 Mette Hasle,1 Helle Bogetofte,1 Ida Olesrud,1 Stefanie Binzer,3 Charlotte Madsen,1 Willy Krone,4 Luis Alberto García Rodríguez,5 Rustam Al-Shahi Salman,6 Jesper Hallas,7 David Gaist1,2,81Department of Neurology, Odense University Hospital, Odense, Denmark2Department of Clinical Research, Neurology Research Unit, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark3Department of Neurology, Lillebaelt?Hospital, Kolding, Denmark4Department of Radiology, Odense University Hospital, Odense, Denmark5Centro Espa?ol Investigación Farmacoepidemiológica (CEIFE), Madrid, Spain6Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom7Clinical Pharmacology and Pharmacy, Department of Public Health, University of Southern Denmark, Odense, Denmark8Odense Patient data Explorative Network (OPEN), Odense University Hospital, Odense, DenmarkCorrespondence: David GaistDept. Neurology, Odense University Hospital, J.B. Winsl?wsvej 4, 5000 Odense C, DenmarkTel +45 65412485Fax +45 65413389Email dgaist@health.sdu.dkABSTRACTPurpose: To establish the validity of intracerebral hemorrhage (ICH) diagnoses in the Danish Stroke Registry (DSR) and the Danish National Patient Registry (DNPR).Patients and methods: Based on discharge summaries and brain imaging reports, we estimated the positive predictive value (PPV) of a first-ever diagnosis code for ICH (ICD-10, code I61) for all patients in the Region of Southern Denmark (1.2 million) during 2009-2017 according to either DNPR or DSR. We estimated PPVs for any non-traumatic ICH (a-ICH) and spontaneous ICH (s-ICH) alone (ie, without underlying structural cause). We also calculated the sensitivity of these diagnoses in each of the registers. Finally, we classified the location of verified s-ICH.Results: A total of 3,956 patients with ICH diagnosis codes were studied (DSR only: 87; DNPR only: 1,513; both registries: 2,356). In the DSR, the PPVs were 86.5% (95%CI, 85.1-87.8) for a-ICH, and 81.8% (95%CI, 80.2-83.3) for s-ICH. The PPVs in DNPR (discharge code, primary diagnostic position) were 76.2% (95%CI, 74.7-77.6) for a-ICH, and 70.2% (95%CI, 68.6-71.8) for s-ICH. Sensitivity for a-ICH and s-ICH was 76.4% (95%CI, 74.8-78.0) and 78.7% (95%CI, 77.1-80.2) in DSR; and 87.3% (95%CI, 86.0-88.5), 87.7% (95%CI, 86.3-88.9) in DNPR. The location of verified s-ICH was lobar (39%), deep (33.6%), infratentorial (13.2%), large unclassifiable (11%), isolated intraventricular (1.9%), or unclassifiable due to insufficient information (1.3%).Conclusion: The validity of a-ICH diagnoses is high in both registries. For s-ICH, PPV was higher in DSR, while sensitivity was higher in DNPR. The location of s-ICH was similar to distributions seen in other populations.Keywords: Stroke, intracerebral hemorrhage, epidemiology, validity, register-based researchIntroductionAdministrative registries that routinely collect data at a population level can be useful resources for studies of temporal trends in cerebrovascular disorders, ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"ZDmEEQ0R","properties":{"formattedCitation":"\\super 1\\uc0\\u8211{}5\\nosupersub{}","plainCitation":"1–5","noteIndex":0},"citationItems":[{"id":1156,"uris":[""],"uri":[""],"itemData":{"id":1156,"type":"article-journal","abstract":"Seasonal variation in the occurrence of cerebrovascular disease has been reported, but data about subarachnoid hemorrhage (SAH) are few and inconclusive. We conducted a nationwide population-based study in Denmark to examine any seasonal pattern of hospitalization and case fatality of SAH. We identified 9,367 patients with SAH and found a modest indication of overall seasonal variation for the risk of hospitalization with this diagnosis. The seasonal pattern, with the highest incidence in January and the nadir in July, was mostly apparent for subjects aged >65 years (peak-to-trough ratio = 1.18; 95% CI 1.04-1.32). There was little difference by sex. The overall 30-day case fatality rate was 38% and showed less seasonal variation. We found evidence of weak seasonal variation in hospitalization for SAH and almost no seasonal variation in a 30-day case fatality rate after SAH.","container-title":"Neuroepidemiology","DOI":"10.1159/000081047","ISSN":"0251-5350","issue":"1-2","journalAbbreviation":"Neuroepidemiology","language":"eng","note":"PMID: 15459507","page":"32-37","source":"PubMed","title":"Seasonal variation in hospitalization and case fatality of subarachnoid hemorrhage - a nationwide danish study on 9,367 patients","volume":"24","author":[{"family":"Fischer","given":"Thomas"},{"family":"Johnsen","given":"S?ren P."},{"family":"Pedersen","given":"Lars"},{"family":"Gaist","given":"David"},{"family":"S?rensen","given":"Henrik T."},{"family":"Rothman","given":"Kenneth J."}],"issued":{"date-parts":[["2005"]]}}},{"id":1184,"uris":[""],"uri":[""],"itemData":{"id":1184,"type":"article-journal","abstract":"BACKGROUND: Subarachnoid hemorrhage accounts for 2% to 5% of all strokes and is associated with high morbidity and mortality rates. Reports in the literature show that case-fatality rates vary with time and according to geographical area.\nOBJECTIVE: The objective of the study was to evaluate the case-fatality rates in subarachnoid hemorrhage at 1 and 6 months and to determine trends in these rates over 22 years using a population-based registry.\nMETHODS: The Dijon Stroke Registry has enabled us to perform a comprehensive analysis of subarachnoid hemorrhage diagnosed in a population of >150 000 inhabitants hospitalized between 1985 and 2006 in the Dijon University Hospital, which has both a neurosurgery unit and a neuroradiology unit. Diagnosis was based on clinical and neuroimaging features and, when necessary, on lumbar puncture.\nRESULTS: Case-fatality rates for hospitalized subarachnoid hemorrhages at 1 and 6 months were 15.59% (95% confidence interval [CI], 9.37-25.34) and 16.84% (95% CI, 10.33-26.78), respectively. From 1985 to 1995, case-fatality rates for SAH at 1 and 6 months were 17.1% (95% CI, 8.1-34.2) and 17.7% (95% CI, 9.6-31.3), whereas from 1996 to 2006, they were 20.2% (95% CI, 10.2-37.8) and 19.7% (95% CI, 11.1-33.6), respectively.\nCONCLUSION: Case-fatality rates for hospitalized subarachnoid hemorrhages in this population-based study remained stable over 22 years, suggesting that this stroke subtype is still a very severe disease despite early management. Most deaths occurred during the first 30 days. Further work is necessary to evaluate levels of prehospital case-fatality in our population-based registry.","container-title":"Neurosurgery","DOI":"10.1227/01.NEU.0000369512.58898.99","ISSN":"1524-4040","issue":"6","journalAbbreviation":"Neurosurgery","language":"eng","note":"PMID: 20386139","page":"1039-1043; discussion 1043","source":"PubMed","title":"Trends in case-fatality rates in hospitalized nontraumatic subarachnoid hemorrhage: results of a population-based study in Dijon, France, from 1985 to 2006","title-short":"Trends in case-fatality rates in hospitalized nontraumatic subarachnoid hemorrhage","volume":"66","author":[{"family":"Biotti","given":"Damien"},{"family":"Jacquin","given":"Agnès"},{"family":"Boutarbouch","given":"Mahjouba"},{"family":"Bousquet","given":"Olivier"},{"family":"Durier","given":"Jér?me"},{"family":"Ben Salem","given":"Douraied"},{"family":"Salem","given":"Doura?eb Ben"},{"family":"Ricolfi","given":"Frederic"},{"family":"Beaurain","given":"Jacques"},{"family":"Osseby","given":"Guy-Victor"},{"family":"Moreau","given":"Thibault"},{"family":"Giroud","given":"Maurice"},{"family":"Béjot","given":"Yannick"}],"issued":{"date-parts":[["2010",6]]}}},{"id":1195,"uris":[""],"uri":[""],"itemData":{"id":1195,"type":"article-journal","abstract":"OBJECTIVES: To examine 18-year trends in short-term and long-term stroke mortality and the prognostic influence of comorbidity.\nMETHODS: We conducted a nationwide population-based cohort study. Using the Danish National Registry of Patients, covering all Danish hospitals, we identified all 219,354 patients with a first-time hospitalization for stroke during 1994-2011. We computed standardized 30-day, 1-year, and 5-year mortality by sex. Comorbidity categories were defined by Charlson Comorbidity Index scores of 0 (none), 1 (moderate), 2 (severe), and 3 or more (very severe). Calendar periods of diagnosis (1994-1998, 1999-2003, 2004-2008, and 2009-2011) and comorbidity categories were compared by means of mortality rate ratios based on Cox regression.\nRESULTS: Over time, the 30-day mortality rate ratio adjusted for age, sex, and comorbidity decreased by approximately 45% for ischemic stroke (standardized risk decreased from 17.2% in 1994-1998 to 10.6% in 2009-2011) and by 35% for intracerebral hemorrhage (from 43.2% to 33.8%). The absolute mortality reduction occurred for all levels of comorbidity. Five-year mortality risk decreased from 56.4% in 1994-1998 to 46.1% in 2004-2008 for ischemic stroke and from 66.1% to 61.0% for intracerebral hemorrhage. Comparing very severe comorbidity with no comorbidity, 30-day and 5-year mortality rate ratios were both approximately 2.5-fold increased for ischemic stroke and 1.7-fold increased for intracerebral hemorrhage.\nCONCLUSIONS: Short- and long-term mortality improved considerably between 1994 and 2011 for all types of stroke. Short-term mortality improved regardless of comorbidity burden. However, comorbidity burden was a strong prognostic factor for both short- and long-term mortality.","container-title":"Neurology","DOI":"10.1212/WNL.0000000000000062","ISSN":"1526-632X","issue":"4","journalAbbreviation":"Neurology","language":"eng","note":"PMID: 24363134","page":"340-350","source":"PubMed","title":"Eighteen-year trends in stroke mortality and the prognostic influence of comorbidity","volume":"82","author":[{"family":"Schmidt","given":"Morten"},{"family":"Jacobsen","given":"Jacob B."},{"family":"Johnsen","given":"S?ren P."},{"family":"B?tker","given":"Hans E."},{"family":"S?rensen","given":"Henrik T."}],"issued":{"date-parts":[["2014",1,28]]}}},{"id":47,"uris":[""],"uri":[""],"itemData":{"id":47,"type":"article-journal","DOI":"10.1001/jama.2017.0639","journalAbbreviation":"JAMA","page":"836-846","title":"Association of antithrombotic drug use with subdural hematoma risk","volume":"317","author":[{"family":"Gaist","given":"D."},{"family":"García Rodríguez","given":"LA"},{"family":"Hellfritzsch","given":"M"},{"family":"Poulsen","given":"FR"},{"family":"Halle","given":"B"},{"family":"Hallas","given":"J."},{"family":"Potteg?rd","given":"A"}],"issued":{"date-parts":[["2017"]]}}},{"id":1182,"uris":[""],"uri":[""],"itemData":{"id":1182,"type":"article-journal","abstract":"BACKGROUND: Up-to-date epidemiological stroke studies are important for healthcare planning and evaluating prevention strategies. This population-based study investigates temporal trends in stroke incidence and case-fatality in southern Sweden.\nMETHODS: First-ever stroke cases in the local catchment area of Sk?ne University Hospital in Lund, Sweden, between March, 2015 and February, 2016, were included from several sources, including 2 prospective hospital-based registers, retrospective screening of primary care visits, and autopsy registers. Stroke incidence and 28-day case-fatality rates were compared with data from this area obtained through similar methodology between March, 2001 and February, 2002.\nRESULTS: Altogether, 456 and 413 first-ever stroke patients were identified during the earlier and later time periods respectively. The age- and sex-standardized stroke incidence rates decreased from 246 (95% CI 224-270) to 165 (95% CI 149-182) per 100,000 people. However, incidence remained unaltered among those <65 years. Early case-fatality decreased from 14 to 11% (p = 0.165). -Conclusion: First-ever stroke incidence in southern Sweden has decreased with 33% since the beginning of this millenni-um. Incidence rates have decreased among the elderly but remain unchanged among younger age groups. Our findings warrant further studies on trends in risk factor profiles and effects of prevention strategies, and heightened focus on stroke in the young.","container-title":"Neuroepidemiology","DOI":"10.1159/000487948","ISSN":"1423-0208","issue":"3-4","journalAbbreviation":"Neuroepidemiology","language":"eng","note":"PMID: 29621789","page":"174-182","source":"PubMed","title":"Temporal Trends of Stroke Epidemiology in Southern Sweden: A Population-Based Study on Stroke Incidence and Early Case-Fatality","title-short":"Temporal Trends of Stroke Epidemiology in Southern Sweden","volume":"50","author":[{"family":"Aked","given":"Joseph"},{"family":"Delavaran","given":"Hossein"},{"family":"Norrving","given":"Bo"},{"family":"Lindgren","given":"Arne"}],"issued":{"date-parts":[["2018"]]}}}],"schema":""} 1–5 and in observational research focusing on the cause, treatment and course of stroke. ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"foAGp6cL","properties":{"formattedCitation":"\\super 6\\uc0\\u8211{}20\\nosupersub{}","plainCitation":"6–20","noteIndex":0},"citationItems":[{"id":104,"uris":[""],"uri":[""],"itemData":{"id":104,"type":"article-journal","abstract":"OBJECTIVE: To estimate the risk of occurrence of subarachnoid haemorrhage in first degree relatives (parents, siblings, children) of patients with subarachnoid haemorrhage.\nDESIGN: Population based cohort study using data from the Danish National Discharge Registry and the Central Person Registry.\nSUBJECTS: Incident cases of subarachnoid haemorrhage admitted to hospital from 1977 to 1995 (9367 patients) and their first degree relatives (14 781).\nMAIN OUTCOME MEASURES: The incidence rate of subarachnoid haemorrhage was determined for the relatives and compared with that of the entire population, standardised for age, sex, and calendar period. This process was repeated for patients discharged from neurosurgery units, as diagnoses from these wards had high validity (93%).\nRESULTS: 18 patients had a total of 19 first degree relatives with subarachnoid haemorrhage during the study period, corresponding to a standardised incidence ratio of 2.9 (95% confidence interval 1.9 to 4.6). Patients discharged from neurosurgery wards had a higher standardised incidence ratio (4.5, 2.7 to 7.3).\nCONCLUSIONS: First degree relatives of patients with subarachnoid haemorrhage have a threefold to fivefold increased risk of subarachnoid haemorrhage compared with the general population.","container-title":"BMJ (Clinical research ed.)","ISSN":"0959-8138","issue":"7228","journalAbbreviation":"BMJ","language":"eng","note":"PMID: 10634731\nPMCID: PMC27258","page":"141-145","source":"PubMed","title":"Risk of subarachnoid haemorrhage in first degree relatives of patients with subarachnoid haemorrhage: follow up study based on national registries in Denmark","title-short":"Risk of subarachnoid haemorrhage in first degree relatives of patients with subarachnoid haemorrhage","volume":"320","author":[{"family":"Gaist","given":"D."},{"family":"Vaeth","given":"M."},{"family":"Tsiropoulos","given":"I."},{"family":"Christensen","given":"K."},{"family":"Corder","given":"E."},{"family":"Olsen","given":"J."},{"family":"S?rensen","given":"H. T."}],"issued":{"date-parts":[["2000",1,15]]}}},{"id":1166,"uris":[""],"uri":[""],"itemData":{"id":1166,"type":"article-journal","abstract":"BACKGROUND AND PURPOSE: Few studies have assessed the overall importance of genetic factors on stroke risk, and the results have been contradictory. We used a large, population-based twin register and nationwide registries of death and hospitalization with long-term follow-up to estimate the effect of genetic factors on the risk of stroke.\nMETHODS: Through the population-based Danish Twin Register, we identified same-sex twin pairs born in 1870 through 1952 for whom at least 1 twin was recorded under a stroke diagnosis in the Register of Causes of Death or the Danish National Discharge Register. From the day of the first stroke event in each twin pair, the live co-twins were followed up for stroke. In survival analyses, we estimated the age- and sex-adjusted effect of zygosity on the risk of stroke death or hospitalization for stroke. Concordance rates, tetrachoric correlations, and heritability were also assessed.\nRESULTS: Thirty-five of 351 monozygotic pairs (10%) and 34 of 639 dizygotic pairs (5%) were concordant for stroke death. The age- and sex-adjusted relative risk of stroke death in monozygotic compared with dizygotic co-twins was 2.1 (95% CI, 1.3 to 3.3). The probandwise concordance rates were 0.18 (95% CI, 0.14 to 0.22) for monozygotic and 0.10 (95% CI, 0.08 to 0.13) for dizygotic pairs. Thirty-three of 309 monozygotic pairs (11%) and 39 of 560 dizygotic pairs (7%) were concordant for stroke hospitalization or stroke death. The age- and sex-adjusted relative risk of stroke hospitalization or stroke death in monozygotic compared with dizygotic co-twins was 1.5 (95% CI, 0.9 to 2.4). The probandwise concordance rates were 0.19 (95% CI, 0.15 to 0.24) for monozygotic and 0.13 (95% CI, 0.10 to 0.16) for dizygotic pairs. The heritability estimates were 0.32 for the liability to stroke death and 0.17 for the liability to stroke hospitalization or stroke death.\nCONCLUSIONS: The observed increased risk of stroke death and stroke hospitalization in monozygotic compared with dizygotic co-twins suggests that genetic factors increase the risk of stroke and that the size of this effect is moderate.","container-title":"Stroke","DOI":"10.1161/hs0302.103619","ISSN":"1524-4628","issue":"3","journalAbbreviation":"Stroke","language":"eng","note":"PMID: 11872902","page":"769-774","source":"PubMed","title":"Genetic liability in stroke: a long-term follow-up study of Danish twins","title-short":"Genetic liability in stroke","volume":"33","author":[{"family":"Bak","given":"S?ren"},{"family":"Gaist","given":"David"},{"family":"Sindrup","given":"S?ren Hein"},{"family":"Skytthe","given":"Axel"},{"family":"Christensen","given":"Kaare"}],"issued":{"date-parts":[["2002",3]]}}},{"id":285,"uris":[""],"uri":[""],"itemData":{"id":285,"type":"article-journal","abstract":"BACKGROUND AND PURPOSE: Nonsteroidal anti-inflammatory drugs (NSAIDs) have been associated with bleeding complications and may affect the risk of hemorrhagic stroke through inhibition of platelet cyclooxygenase-1. We performed a population-based case-control study to estimate the risk of intracerebral hemorrhage, subarachnoid hemorrhage, and ischemic stroke in users of NSAIDs.\nMETHODS: We used a population-based patient registry to identify all patients with a first-ever stroke discharge diagnosis in the period of 1994 to 1999. All diagnoses were validated according to predefined criteria. We selected 40 000 random controls from the background population. Information on drug use for cases and controls was retrieved from a prescription registry. Odds ratios were adjusted for age, sex, calendar year, and use of other medication. To evaluate the effect of various potential confounders not recorded in the register, we performed separate analyses on data from 2 large population-based surveys with more detailed information on risk factors.\nRESULTS: The cases were classified as intracerebral hemorrhage (n=659), subarachnoid hemorrhage (n=208), and ischemic stroke (n=2717). The adjusted odds ratio of stroke in current NSAID users compared with never users was 1.2 (95% CI, 0.9 to 1.6) for intracerebral hemorrhage, 1.2 (95% CI, 0.7 to 2.1) for subarachnoid hemorrhage and 1.2 (95% confidence interval, 1.0 to 1.4) for ischemic stroke. The survey data indicated that additional confounder control would not have led to an increase in relative risk estimates.\nCONCLUSIONS: Current exposure to NSAIDs is not a risk factor for intracerebral hemorrhage or subarachnoid hemorrhage. Furthermore, NSAIDs probably offer no protection against first-ever ischemic stroke.","container-title":"Stroke","ISSN":"1524-4628","issue":"2","journalAbbreviation":"Stroke","language":"eng","note":"PMID: 12574546","page":"379-386","source":"PubMed","title":"Risk of stroke associated with nonsteroidal anti-inflammatory drugs: a nested case-control study","title-short":"Risk of stroke associated with nonsteroidal anti-inflammatory drugs","volume":"34","author":[{"family":"Bak","given":"S?ren"},{"family":"Andersen","given":"Morten"},{"family":"Tsiropoulos","given":"Ioannis"},{"family":"García Rodríguez","given":"Luis Alberto"},{"family":"Hallas","given":"Jesper"},{"family":"Christensen","given":"Kaare"},{"family":"Gaist","given":"David"}],"issued":{"date-parts":[["2003",2]]}}},{"id":1187,"uris":[""],"uri":[""],"itemData":{"id":1187,"type":"article-journal","abstract":"OBJECTIVE: Previous studies have estimated that wake-up strokes comprise 8%to 28% of all ischemic strokes, but these studies were either small or not population-based. We sought to establish the proportion and event rate of wake-up strokes in a large population-based study and to compare patients who awoke with stroke symptoms with those who were awake at time of onset.\nMETHODS: First-time and recurrent ischemic strokes among residents of the Greater Cincinnati/Northern Kentucky region (population 1.3 million) in 2005 were identified using International Classification of Diseases-9 codes 430-436 and verified via study physician review. Ischemic strokes in patients aged 18 years and older presenting to an emergency department were included. Baseline characteristics were ascertained, along with discharge modified Rankin Scale scores and 90-day mortality.\nRESULTS: We identified 1,854 ischemic strokes presenting to an emergency department, of which 273 (14.3%) were wake-up strokes. There were no differences between wake-up strokes and all other strokes with regard to clinical features or outcomes except for minor differences in age and baseline retrospective NIH Stroke Scale score. The adjusted wake-up stroke event rate was 26.0/100,000. Of the wake-up strokes, at least 98 (35.9%) would have been eligible for thrombolysis if arrival time were not a factor.\nCONCLUSIONS: Within our population, approximately 14% of ischemic strokes presenting to an emergency department were wake-up strokes. Wake-up strokes cannot be distinguished from other strokes by clinical features or outcome. We estimate that approximately 58,000 patients with wake-up strokes presented to an emergency department in the United States in 2005.","container-title":"Neurology","DOI":"10.1212/WNL.0b013e318219fb30","ISSN":"1526-632X","issue":"19","journalAbbreviation":"Neurology","language":"eng","note":"PMID: 21555734\nPMCID: PMC3100086","page":"1662-1667","source":"PubMed","title":"Population-based study of wake-up strokes","volume":"76","author":[{"family":"Mackey","given":"J."},{"family":"Kleindorfer","given":"D."},{"family":"Sucharew","given":"H."},{"family":"Moomaw","given":"C. J."},{"family":"Kissela","given":"B. M."},{"family":"Alwell","given":"K."},{"family":"Flaherty","given":"M. L."},{"family":"Woo","given":"D."},{"family":"Khatri","given":"P."},{"family":"Adeoye","given":"O."},{"family":"Ferioli","given":"S."},{"family":"Khoury","given":"J. C."},{"family":"Hornung","given":"R."},{"family":"Broderick","given":"J. P."}],"issued":{"date-parts":[["2011",5,10]]}}},{"id":71,"uris":[""],"uri":[""],"itemData":{"id":71,"type":"article-journal","abstract":"OBJECTIVE: To investigate the relationship between hemorrhagic stroke and use of antiplatelets and warfarin using data from The Health Improvement Network.\nMETHODS: A total of 1,797 incident cases of intracerebral hemorrhage (ICH) and 1,340 of subarachnoid hemorrhage (SAH) were ascertained. Density-based sampling was used to select 10,000 controls free from hemorrhagic stroke. Risk of hemorrhagic stroke was evaluated in current users and nonusers of antiplatelets and warfarin. Unconditional logistic regression models were used to adjust for age, sex, calendar year, alcohol, body mass index, hypertension, and health services utilization.\nRESULTS: Aspirin use was not associated with an increased risk of ICH (odds ratio [OR] 1.06, 95% confidence interval [CI] 0.93-1.21), but was associated with a decreased risk of SAH (OR 0.82, 95% CI 0.67-1.00), compared with no therapy. Aspirin use ≥3 years was associated with a decreased risk of SAH (OR 0.63, 95% CI 0.45-0.90) compared with no therapy. Warfarin use was associated with a greatly increased risk of ICH (OR 2.82, 95% CI 2.26-3.53) and a moderately increased risk of SAH (OR 1.67, 95% CI 1.15-2.43) compared with no therapy. International normalized ratio values ≥3 carried a marked risk of ICH (OR 7.01, 95% CI 4.10-11.99).\nCONCLUSION: Aspirin is not associated with a risk of ICH compared with no therapy. Chronic low-dose aspirin treatment may have a protective effect on the risk of SAH. Warfarin users in this study cohort were at a much higher risk of ICH than those receiving no therapy, with a marked association with international normalized ratio >3.","container-title":"Neurology","DOI":"10.1212/WNL.0b013e31829e6ffa","ISSN":"1526-632X","issue":"6","journalAbbreviation":"Neurology","language":"eng","note":"PMID: 23843464","page":"566-574","source":"PubMed","title":"Antithrombotic drugs and risk of hemorrhagic stroke in the general population","volume":"81","author":[{"family":"García-Rodríguez","given":"Luis A."},{"family":"Gaist","given":"David"},{"family":"Morton","given":"Jonathan"},{"family":"Cookson","given":"Charlotte"},{"family":"González-Pérez","given":"Antonio"}],"issued":{"date-parts":[["2013",8,6]]}}},{"id":73,"uris":[""],"uri":[""],"itemData":{"id":73,"type":"article-journal","abstract":"OBJECTIVE: To investigate short-term case fatality and long-term mortality after intracerebral hemorrhage (ICH) and subarachnoid hemorrhage (SAH) using data from The Health Improvement Network database.\nMETHODS: Thirty-day case fatality was stratified by age, sex, and calendar year after ICH and SAH using logistic regression. Cox proportional hazards regression analyses were used to estimate the risk of death during the first year of follow-up and survivors at 1 year.\nRESULTS: Case fatality after ICH was 42.0%, compared with 28.7% after SAH. It increased with age (ICH: 29.7% for 20-49 years, 54.6% for 80-89 years; SAH: 20.3% for 20-49 years, 56.7% for 80-89 years; both p-trend < 0.001), and decreased over the period 2000-2001 to 2006-2008 (ICH: from 53.1% to 35.8%, p-trend < 0.001; SAH: from 33.3% to 24.7%, p-trend = 0.02). Risk of death was significantly higher among stroke patients during the first year of follow-up compared with controls (ICH: hazard ratio [HR] 2.60, 95% confidence interval [CI] 2.09-3.24, p < 0.01; SAH: HR 2.87, 95% CI 2.07-3.97, p < 0.01) and remained elevated among survivors at 1 year (ICH: HR 2.02, 95% CI 1.75-2.32, p < 0.01; SAH: HR 1.32, 95% CI 1.02-1.69, p = 0.03).\nCONCLUSIONS: More than one-third of individuals die in the first month after hemorrhagic stroke, and patients younger than 50 years are more likely to die after ICH than SAH. Short-term case fatality has decreased over time. Patients who survive hemorrhagic stroke have a continuing elevated risk of death compared with matched individuals from the general population.","container-title":"Neurology","DOI":"10.1212/WNL.0b013e31829e6eff","ISSN":"1526-632X","issue":"6","journalAbbreviation":"Neurology","language":"eng","note":"PMID: 23843467","page":"559-565","source":"PubMed","title":"Mortality after hemorrhagic stroke: data from general practice (The Health Improvement Network)","title-short":"Mortality after hemorrhagic stroke","volume":"81","author":[{"family":"González-Pérez","given":"Antonio"},{"family":"Gaist","given":"David"},{"family":"Wallander","given":"Mari-Ann"},{"family":"McFeat","given":"Gillian"},{"family":"García-Rodríguez","given":"Luis A."}],"issued":{"date-parts":[["2013",8,6]]}}},{"id":1164,"uris":[""],"uri":[""],"itemData":{"id":1164,"type":"article-journal","abstract":"BACKGROUND: We wished to examine the impact of antiplatelet drug discontinuation on recurrent stroke and all-cause mortality.\nMETHODS: We identified a cohort of incident ischaemic stroke patients in a Danish stroke registry, 2007-2011. Using population-based registries we assessed subjects' drug use and followed them up for stroke recurrence, or all-cause death. Person-time was classified by antiplatelet drug use into current use, recent use (≤150 days after last use), and non-use (>150 days after last use). Lipid-lowering drug (LLD) use was classified by the same rules. We used Cox proportional hazard models to calculate the adjusted hazard ratio (HR) and corresponding 95% confidence intervals (CIs) for the risk of recurrent stroke or death associated with discontinuation of antiplatelet or LLD drugs.\nRESULTS: Among 4,670 stroke patients followed up for up a median of 1.5 years, 237 experienced a second stroke and 600 died. Compared with current antiplatelet drug use, both recent use (1.3 (0.8-2.0)), and non-use (1.3 (0.8-1.9)) were associated with increased recurrent stroke risk. The corresponding HRs of death were 1.9 (1.4-2.5) for recent and 1.8 (1.4-2.3) for non-use of antiplatelet drugs. Recent statin use was associated with markedly increased risk of death (2.1 (1.7-2.6)), and only marginally with recurrent stroke (1.2 (0.9-1.6)).\nCONCLUSIONS: Antiplatelet drug discontinuation may be associated with an increased recurrent stroke risk. Our results on death risk indicate that non-pharmacological biases, such as 'sick stopper', may threaten the validity of this risk estimate.","container-title":"Neuroepidemiology","DOI":"10.1159/000365732","ISSN":"1423-0208","issue":"1","journalAbbreviation":"Neuroepidemiology","language":"eng","note":"PMID: 25323533","page":"57-64","source":"PubMed","title":"Discontinuation of antiplatelet treatment and risk of recurrent stroke and all-cause death: a cohort study","title-short":"Discontinuation of antiplatelet treatment and risk of recurrent stroke and all-cause death","volume":"43","author":[{"family":"?stergaard","given":"Kamilla"},{"family":"Potteg?rd","given":"Anton"},{"family":"Hallas","given":"Jesper"},{"family":"Bak","given":"S?ren"},{"family":"Christensen","given":"René","non-dropping-particle":"dePont"},{"family":"Gaist","given":"David"}],"issued":{"date-parts":[["2014"]]}}},{"id":1197,"uris":[""],"uri":[""],"itemData":{"id":1197,"type":"article-journal","abstract":"OBJECTIVES: To examine whether preadmission use of nonaspirin nonsteroidal anti-inflammatory drugs (NSAIDs) influenced 30-day stroke mortality.\nMETHODS: We conducted a nationwide population-based cohort study. Using medical databases, we identified all first-time stroke hospitalizations in Denmark between 2004 and 2012 (n = 100,043) and subsequent mortality. We categorized NSAID use as current (prescription redemption within 60 days before hospital admission), former, and nonuse. Current use was further classified as new or long-term use. Cox regression was used to compute hazard ratios (HRs) of death within 30 days, controlling for potential confounding through multivariable adjustment and propensity score matching.\nRESULTS: The adjusted HR of death for ischemic stroke was 1.19 (95% confidence interval [CI]: 1.02-1.38) for current users of selective cyclooxygenase (COX)-2 inhibitors compared with nonusers, driven by the effect among new users (1.42, 95% CI: 1.14-1.77). Comparing the different COX-2 inhibitors, the HR was driven by new use of older traditional COX-2 inhibitors (1.42, 95% CI: 1.14-1.78) among which it was 1.53 (95% CI: 1.02-2.28) for etodolac and 1.28 (95% CI: 0.98-1.68) for diclofenac. The propensity score-matched analysis supported the association between older COX-2 inhibitors and ischemic stroke mortality. There was no association for former users. Mortality from intracerebral hemorrhage was not associated with use of nonselective NSAIDs or COX-2 inhibitors.\nCONCLUSIONS: Preadmission use of COX-2 inhibitors was associated with increased 30-day mortality after ischemic stroke, but not hemorrhagic stroke. Use of nonselective NSAIDs at time of admission was not associated with mortality from ischemic stroke or intracerebral hemorrhage.","container-title":"Neurology","DOI":"10.1212/WNL.0000000000001024","ISSN":"1526-632X","issue":"22","journalAbbreviation":"Neurology","language":"eng","note":"PMID: 25378670","page":"2013-2022","source":"PubMed","title":"Preadmission use of nonaspirin nonsteroidal anti-inflammatory drugs and 30-day stroke mortality","volume":"83","author":[{"family":"Schmidt","given":"Morten"},{"family":"Hováth-Puhó","given":"Erzsébet"},{"family":"Christiansen","given":"Christian Fynbo"},{"family":"Petersen","given":"Karin L."},{"family":"B?tker","given":"Hans Erik"},{"family":"S?rensen","given":"Henrik Toft"}],"issued":{"date-parts":[["2014",11,25]]}}},{"id":107,"uris":[""],"uri":[""],"itemData":{"id":107,"type":"article-journal","abstract":"OBJECTIVE: To study the effectiveness and safety of the non-vitamin K antagonist oral anticoagulants (novel oral anticoagulants, NOACs) dabigatran, rivaroxaban, and apixaban compared with warfarin in anticoagulant na?ve patients with atrial fibrillation.\nDESIGN: Observational nationwide cohort study.\nSETTING: Three Danish nationwide databases, August 2011 to October 2015.\nPARTICIPANTS: 61?678 patients with non-valvular atrial fibrillation who were na?ve to oral anticoagulants and had no previous indication for valvular atrial fibrillation or venous thromboembolism. The study population was distributed according to treatment type: warfarin (n=35?436, 57%), dabigatran 150 mg (n=12?701, 21%), rivaroxaban 20 mg (n=7192, 12%), and apixaban 5 mg (n=6349, 10%).\nMAIN OUTCOME MEASURES: Effectiveness outcomes defined a priori were ischaemic stroke; a composite of ischaemic stroke or systemic embolism; death; and a composite of ischaemic stroke, systemic embolism, or death. Safety outcomes were any bleeding, intracranial bleeding, and major bleeding.\nRESULTS: When the analysis was restricted to ischaemic stroke, NOACs were not significantly different from warfarin. During one year follow-up, rivaroxaban was associated with lower annual rates of ischaemic stroke or systemic embolism (3.0% v 3.3%, respectively) compared with warfarin: hazard ratio 0.83 (95% confidence interval 0.69 to 0.99). The hazard ratios for dabigatran and apixaban (2.8% and 4.9% annually, respectively) were non-significant compared with warfarin. The annual risk of death was significantly lower with apixaban (5.2%) and dabigatran (2.7%) (0.65, 0.56 to 0.75 and 0.63, 0.48 to 0.82, respectively) compared with warfarin (8.5%), but not with rivaroxaban (7.7%). For the combined endpoint of any bleeding, annual rates for apixaban (3.3%) and dabigatran (2.4%) were significantly lower than for warfarin (5.0%) (0.62, 0.51 to 0.74). Warfarin and rivaroxaban had comparable annual bleeding rates (5.3%).\nCONCLUSION: All NOACs seem to be safe and effective alternatives to warfarin in a routine care setting. No significant difference was found between NOACs and warfarin for ischaemic stroke. The risks of death, any bleeding, or major bleeding were significantly lower for apixaban and dabigatran compared with warfarin.","container-title":"BMJ (Clinical research ed.)","ISSN":"1756-1833","journalAbbreviation":"BMJ","language":"eng","note":"PMID: 27312796","page":"i3189","source":"PubMed","title":"Comparative effectiveness and safety of non-vitamin K antagonist oral anticoagulants and warfarin in patients with atrial fibrillation: propensity weighted nationwide cohort study","title-short":"Comparative effectiveness and safety of non-vitamin K antagonist oral anticoagulants and warfarin in patients with atrial fibrillation","volume":"353","author":[{"family":"Larsen","given":"Torben Bjerregaard"},{"family":"Skj?th","given":"Flemming"},{"family":"Nielsen","given":"Peter Br?nnum"},{"family":"Kj?ldgaard","given":"Jette Nordstr?m"},{"family":"Lip","given":"Gregory Y. H."}],"issued":{"date-parts":[["2016"]]}}},{"id":1192,"uris":[""],"uri":[""],"itemData":{"id":1192,"type":"article-journal","abstract":"BACKGROUND AND PURPOSE: The prognostic impact of glucocorticoids on stroke mortality remains uncertain. We, therefore, examined whether preadmission use of glucocorticoids is associated with short-term mortality after ischemic stroke, intracerebral hemorrhage (ICH), or subarachnoid hemorrhage (SAH).\nMETHODS: We conducted a nationwide population-based cohort study using medical registries in Denmark. We identified all patients with a first-time inpatient diagnosis of stroke between 2004 and 2012. We categorized glucocorticoid use as current use (last prescription redemption ≤90 days before admission), former use, and nonuse. Current use was further classified as new or long-term use. We used Cox regression to compute 30-day mortality rate ratios with 95% confidence intervals (CIs), controlling for confounders.\nRESULTS: We identified 100 042 patients with a first-time stroke. Of these, 83 735 patients had ischemic stroke, 11 779 had ICH, and 4528 had SAH. Absolute mortality risk was higher for current users compared with nonusers for ischemic stroke (19.5% versus 10.2%), ICH (46.5% versus 34.4%), and SAH (35.0% versus 23.2%). For ischemic stroke, the adjusted 30-day mortality rate ratio was increased among current users compared with nonusers (1.58, 95% CI: 1.46-1.71), driven by the effect of glucocorticoids among new users (1.80, 95% CI: 1.62-1.99). Current users had a more modest increase in the adjusted 30-day mortality rate ratio for hemorrhagic stroke (1.26, 95% CI: 1.09-1.45 for ICH and 1.40, 95% CI: 1.01-1.93 for SAH) compared with nonusers. Former use was not substantially associated with mortality.\nCONCLUSIONS: Preadmission use of glucocorticoids was associated with increased 30-day mortality among patients with ischemic stroke, ICH, and SAH.","container-title":"Stroke","DOI":"10.1161/STROKEAHA.115.012231","ISSN":"1524-4628","issue":"3","journalAbbreviation":"Stroke","language":"eng","note":"PMID: 26903585","page":"829-835","source":"PubMed","title":"Preadmission Use of Glucocorticoids and 30-Day Mortality After Stroke","volume":"47","author":[{"family":"Sundb?ll","given":"Jens"},{"family":"Horváth-Puhó","given":"Erzsébet"},{"family":"Schmidt","given":"Morten"},{"family":"Dekkers","given":"Olaf M."},{"family":"Christiansen","given":"Christian F."},{"family":"Pedersen","given":"Lars"},{"family":"B?tker","given":"Hans Erik"},{"family":"S?rensen","given":"Henrik T."}],"issued":{"date-parts":[["2016",3]]}}},{"id":882,"uris":[""],"uri":[""],"itemData":{"id":882,"type":"article-journal","abstract":"Objective?To examine clinical effectiveness and safety of apixaban 2.5 mg, dabigatran 110 mg, and rivaroxaban 15 mg compared with warfarin among patients with atrial fibrillation who had not previously taken an oral anticoagulant.Design?Propensity weighted (inverse probability of treatment weighted) nationwide cohort study.Setting?Individual linked data from three nationwide registries in Denmark.Participants?Patients with non-valvular atrial fibrillation filling a first prescription for an oral anticoagulant from August 2011 to February 2016. Patients who filled a prescription for a standard dose non-vitamin K antagonist oral anticoagulant (novel oral anticoagulants, NOACs) were excluded. To control for baseline differences in the population, a propensity score for receipt of either of the four treatment alternatives was calculated to apply an inverse probability treatment weight.Intervention?Initiated anticoagulant treatment (dabigatran 110 mg, rivaroxaban 15 mg, apixaban 2.5 mg, and warfarin).Main outcome measures?Patients were followed in the registries from onset of treatment for the primary effectiveness outcome of ischaemic stroke/systemic embolism and for the principal safety outcome of any bleeding events.Results?Among 55?644 patients with atrial fibrillation who met inclusion criteria, the cohort was distributed according to treatment: apixaban n=4400; dabigatran n=8875; rivaroxaban n=3476; warfarin n=38?893. The overall mean age was 73.9 (SD 12.7), ranging from a mean of 71.0 (warfarin) to 83.9 (apixaban). During one year of follow-up, apixaban was associated with higher (weighted) event rate of ischaemic stroke/systemic embolism (4.8%), while dabigatran, rivaroxaban, and warfarin had event rates of 3.3%, 3.5%, and 3.7%, respectively. In the comparison between a non-vitamin K antagonist oral anticoagulant and warfarin in the inverse probability of treatment weighted analyses and investigation of the effectiveness outcome, the hazard ratios were 1.19 (95% confidence interval 0.95 to 1.49) for apixaban, 0.89 (0.77 to 1.03) for dabigatran, and 0.89 (0.69 to 1.16) for rivaroxaban. For the principal safety outcome versus warfarin, the hazard ratios were 0.96 (0.73 to 1.27) for apixaban, 0.80 (0.70 to 0.92) for dabigatran, and 1.06 (0.87 to 1.29) for rivaroxaban.Conclusion?In this propensity weighted nationwide study of reduced dose non-vitamin K antagonist oral anticoagulant regimens, apixaban 2.5 mg twice a day was associated with a trend towards higher rates of ischaemic stroke/systemic embolism compared with warfarin, while rivaroxaban 15 mg once a day and dabigatran 110 mg twice a day showed a trend towards lower thromboembolic rates. The results were not significantly different. Rates of bleeding (the principal safety outcome) were significantly lower for dabigatran, but not significantly different for apixaban and rivaroxaban compared with warfarin.","container-title":"BMJ (Clinical research ed.)","ISSN":"1756-1833","journalAbbreviation":"BMJ","language":"eng","note":"PMID: 28188243\nPMCID: PMC5421446","page":"j510","source":"PubMed","title":"Effectiveness and safety of reduced dose non-vitamin K antagonist oral anticoagulants and warfarin in patients with atrial fibrillation: propensity weighted nationwide cohort study","title-short":"Effectiveness and safety of reduced dose non-vitamin K antagonist oral anticoagulants and warfarin in patients with atrial fibrillation","volume":"356","author":[{"family":"Nielsen","given":"Peter Br?nnum"},{"family":"Skj?th","given":"Flemming"},{"family":"S?gaard","given":"Mette"},{"family":"Kj?ldgaard","given":"Jette Nordstr?m"},{"family":"Lip","given":"Gregory Y. H."},{"family":"Larsen","given":"Torben Bjerregaard"}],"issued":{"date-parts":[["2017",2,10]]}}},{"id":1190,"uris":[""],"uri":[""],"itemData":{"id":1190,"type":"article-journal","abstract":"OBJECTIVES: Post-stroke depression and pathological crying are common and potentially serious complications after stroke and should be diagnosed and treated accordingly. Diagnosis and treatment probably rely on clinical experience and may pose certain challenges. We aimed to examine prescription and predictors of antidepressant treatment after ischemic stroke in a clinical setting.\nMATERIALS AND METHODS: In this registry-based follow-up study, consecutive ischemic stroke patients were identified from the Danish Stroke Registry, holding information on antidepressant treatment during admission in Aarhus County from 2003 to 2010. Information on prescription after discharge was obtained from the Danish Prescription Database. Treatment initiation was analyzed using the cumulative incidence method including death as a competing risk. Multiple logistic regression was used to identify potential predictors of treatment.\nRESULTS: Among 5070 consecutive first-ever ischemic stroke patients without prior antidepressant treatment, the cumulative incidence of antidepressant treatment and prescription over 6?months was 35.2% (95% CI: 33.8-36.6). Overall 16.5% (95% CI: 15.5-17.6) started treatment within 14?days corresponding to 48.1% (95% CI: 45.8-50.5) of all treated patients, and the most widely prescribed group of antidepressants was selective serotonin reuptake inhibitors (86%). Increasing stroke severity was associated with higher odds of initiating treatment.\nCONCLUSION: Antidepressant treatment in this real-life clinical setting was common and initiated early, in almost half the treated patients within 14?days. Our results suggest that special focus should be given to the severe strokes as they may have a greater risk of requiring treatment.","container-title":"Acta Neurologica Scandinavica","DOI":"10.1111/ane.12947","ISSN":"1600-0404","issue":"3","journalAbbreviation":"Acta Neurol. Scand.","language":"eng","note":"PMID: 29691834","page":"235-244","source":"PubMed","title":"Prescription and predictors of post-stroke antidepressant treatment: A population-based study","title-short":"Prescription and predictors of post-stroke antidepressant treatment","volume":"138","author":[{"family":"Mortensen","given":"J. K."},{"family":"Johnsen","given":"S. P."},{"family":"Andersen","given":"G."}],"issued":{"date-parts":[["2018",9]]}}},{"id":1169,"uris":[""],"uri":[""],"itemData":{"id":1169,"type":"article-journal","abstract":"OBJECTIVES: To study trends in stroke mortality rates, event rates, and case fatality, and to explain the extent to which the reduction in stroke mortality rates was influenced by changes in stroke event rates or case fatality.\nDESIGN: Population based study.\nSETTING: Person linked routine hospital and mortality data, England.\nPARTICIPANTS: 795?869 adults aged 20 and older who were admitted to hospital with acute stroke or died from stroke.\nMAIN OUTCOME MEASURES: Stroke mortality rates, stroke event rates (stroke admission or stroke death without admission), and case fatality within 30 days after stroke.\nRESULTS: Between 2001 and 2010 stroke mortality rates decreased by 55%, stroke event rates by 20%, and case fatality by 40%. The study population included 358?599 (45%) men and 437?270 (55%) women. Average annual change in mortality rate was -6.0% (95% confidence interval -6.2% to -5.8%) in men and -6.1% (-6.3% to -6.0%) in women, in stroke event rate was -1.3% (-1.4% to -1.2%) in men and -2.1% (-2.2 to -2.0) in women, and in case fatality was -4.7% (-4.9% to -4.5%) in men and -4.4% (-4.5% to -4.2%) in women. Mortality and case fatality but not event rate declined in all age groups: the stroke event rate decreased in older people but increased by 2% each year in adults aged 35 to 54 years. Of the total decline in mortality rates, 71% was attributed to the decline in case fatality (78% in men and 66% in women) and the remainder to the reduction in stroke event rates. The contribution of the two factors varied between age groups. Whereas the reduction in mortality rates in people younger than 55 years was due to the reduction in case fatality, in the oldest age group (≥85 years) reductions in case fatality and event rates contributed nearly equally.\nCONCLUSIONS: Declines in case fatality, probably driven by improvements in stroke care, contributed more than declines in event rates to the overall reduction in stroke mortality. Mortality reduction in men and women younger than 55 was solely a result of a decrease in case fatality, whereas stroke event rates increased in the age group 35 to 54 years. The increase in stroke event rates in young adults is a concern. This suggests that stroke prevention needs to be strengthened to reduce the occurrence of stroke in people younger than 55 years.","container-title":"BMJ (Clinical research ed.)","DOI":"10.1136/bmj.l1778","ISSN":"1756-1833","journalAbbreviation":"BMJ","language":"eng","note":"PMID: 31122927\nPMCID: PMC6529851","page":"l1778","source":"PubMed","title":"Determinants of the decline in mortality from acute stroke in England: linked national database study of 795?869 adults","title-short":"Determinants of the decline in mortality from acute stroke in England","volume":"365","author":[{"family":"Seminog","given":"Olena O."},{"family":"Scarborough","given":"Peter"},{"family":"Wright","given":"F. Lucy"},{"family":"Rayner","given":"Mike"},{"family":"Goldacre","given":"Michael J."}],"issued":{"date-parts":[["2019"]],"season":"22"}}},{"id":1199,"uris":[""],"uri":[""],"itemData":{"id":1199,"type":"article-journal","abstract":"Importance: Stroke remains the second leading cause of death worldwide. Approximately 10% to 15% of all strokes occur in young adults. Information on prognosis and mortality specifically in young adults is limited.\nObjective: To determine short- and long-term mortality risk after stroke in young adults, according to age, sex, and stroke subtype; time trends in mortality; and causes of death.\nDesign, Setting, and Participants: Registry- and population-based study in the Netherlands of 15 527 patients aged 18 to 49 years with first stroke between 1998 and 2010, and follow-up until January 1, 2017. Patients and outcomes were identified through linkage of the national Hospital Discharge Registry, national Cause of Death Registry, and the Dutch Population Register.\nExposures: First stroke occurring at age 18 to 49 years, documented using International Classification of Diseases, Ninth Revision, and International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, codes for ischemic stroke, intracerebral hemorrhage, and stroke not otherwise specified.\nMain Outcomes and Measures: Primary outcome was all-cause cumulative mortality in 30-day survivors at end of follow-up, stratified by age, sex, and stroke subtype, and compared with all-cause cumulative mortality in the general population.\nResults: The study population included 15 527 patients with stroke (median age, 44 years [interquartile range, 38-47 years]; 53.3% women). At end of follow-up, a total of 3540 cumulative deaths had occurred, including 1776 deaths within 30 days after stroke and 1764 deaths (23.2%) during a median duration of follow-up of 9.3 years (interquartile range, 5.9-13.1 years). The 15-year mortality in 30-day survivors was 17.0% (95% CI, 16.2%-17.9%). The standardized mortality rate compared with the general population was 5.1 (95% CI, 4.7-5.4) for ischemic stroke (observed mortality rate 12.0/1000 person-years [95% CI, 11.2-12.9/1000 person-years]; expected rate, 2.4/1000 person-years; excess rate, 9.6/1000 person-years) and the standardized mortality rate for intracerebral hemorrhage was 8.4 (95% CI, 7.4-9.3; observed rate, 18.7/1000 person-years [95% CI, 16.7-21.0/1000 person-years]; expected rate, 2.2/1000 person-years; excess rate, 16.4/1000 person-years).\nConclusions and Relevance: Among young adults aged 18 to 49 years in the Netherlands who were 30-day survivors of first stroke, mortality risk compared with the general population remained elevated up to 15 years later.","container-title":"JAMA","DOI":"10.1001/jama.2019.6560","ISSN":"1538-3598","issue":"21","journalAbbreviation":"JAMA","language":"eng","note":"PMID: 31121602\nPMCID: PMC6547225","page":"2113-2123","source":"PubMed","title":"Association of Stroke Among Adults Aged 18 to 49 Years With Long-term Mortality","volume":"321","author":[{"family":"Ekker","given":"Merel Sanne"},{"family":"Verhoeven","given":"Jamie Inge"},{"family":"Vaartjes","given":"Ilonca"},{"family":"Jolink","given":"Wilhelmus Martinus Tim"},{"family":"Klijn","given":"Catharina Johanna Maria"},{"family":"Leeuw","given":"Frank-Erik","non-dropping-particle":"de"}],"issued":{"date-parts":[["2019"]],"season":"04"}}},{"id":1274,"uris":[""],"uri":[""],"itemData":{"id":1274,"type":"article-journal","abstract":"Background and Purpose- To date, there is still uncertainty about age and sex differences in access to stroke unit treatment and use of intravenous thrombolysis (IVT), while age and sex differences have not been investigated for the new treatment option of mechanical thrombectomy (MT). We, therefore, undertook a complete nationwide analysis of all hospitalized ischemic stroke patients in Germany from 2013 to 2017. Methods- We used the nationwide administrative database of the German Federal Statistical Office and investigated access to stroke unit treatment, IVT, MT, and in-hospital mortality. Patients were subdivided into 6 predefined age groups (20-44, 45-59, 60-69, 70-79, 80-89, and >90 years). Pooled overall and age group estimates were calculated using the random-effects model. To evaluate potential sex disparities, we estimated odds ratios (ORs) with 95% CIs. Results- A total of 1?112?570 patients were hospitalized for first or recurrent ischemic stroke from 2013 to 2017. Overall, stroke unit treatment increased significantly from 66.8% in 2013 to 73.5% in 2017, as did IVT (from 12.4% to 15.9%) and MT (from 2.4% to 5.8%; all P<0.001). Although the difference became smaller over time, patients ≥80 years of age still received significantly less often treatments. Men of all age groups had a significantly higher probability receiving stroke unit treatment (OR, 1.11; 95% CI, 1.09-1.12) and lower in-hospital mortality (OR, 0.91; 95% CI, 0.89-0.93). No disparity was observed in the use of IVT (OR, 1.00; 95% CI, 0.98-1.01), while women of all ages were treated more often with MT (OR, 1.26; 95% CI, 1.22-1.30). Conclusions- Access to stroke unit treatment has to be increased in both older patients and women of all ages. While there was no sex difference in IVT use, it is important to further investigate the significantly higher frequency of MT in women with ischemic stroke irrespective of age.","container-title":"Stroke","DOI":"10.1161/STROKEAHA.119.026723","ISSN":"1524-4628","issue":"12","journalAbbreviation":"Stroke","language":"eng","note":"PMID: 31623547","page":"3494-3502","source":"PubMed","title":"Age and Sex Differences in Ischemic Stroke Treatment in a Nationwide Analysis of 1.11 Million Hospitalized Cases","volume":"50","author":[{"family":"Weber","given":"Ralph"},{"family":"Krogias","given":"Christos"},{"family":"Eyding","given":"Jens"},{"family":"Bartig","given":"Dirk"},{"family":"Meves","given":"Saskia H."},{"family":"Katsanos","given":"Aristeidis H."},{"family":"Caso","given":"Valeria"},{"family":"Hacke","given":"Werner"}],"issued":{"date-parts":[["2019"]]}}}],"schema":""} 6–20 Large clinical databases or medical registers anchored in well-defined populations can furthermore be a particularly attractive solution to the challenge of acquiring valid data over extended time-periods for relatively rare disorders such as intracerebral hemorrhage (ICH). ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"KmJusouI","properties":{"formattedCitation":"\\super 10,21\\uc0\\u8211{}29\\nosupersub{}","plainCitation":"10,21–29","noteIndex":0},"citationItems":[{"id":71,"uris":[""],"uri":[""],"itemData":{"id":71,"type":"article-journal","abstract":"OBJECTIVE: To investigate the relationship between hemorrhagic stroke and use of antiplatelets and warfarin using data from The Health Improvement Network.\nMETHODS: A total of 1,797 incident cases of intracerebral hemorrhage (ICH) and 1,340 of subarachnoid hemorrhage (SAH) were ascertained. Density-based sampling was used to select 10,000 controls free from hemorrhagic stroke. Risk of hemorrhagic stroke was evaluated in current users and nonusers of antiplatelets and warfarin. Unconditional logistic regression models were used to adjust for age, sex, calendar year, alcohol, body mass index, hypertension, and health services utilization.\nRESULTS: Aspirin use was not associated with an increased risk of ICH (odds ratio [OR] 1.06, 95% confidence interval [CI] 0.93-1.21), but was associated with a decreased risk of SAH (OR 0.82, 95% CI 0.67-1.00), compared with no therapy. Aspirin use ≥3 years was associated with a decreased risk of SAH (OR 0.63, 95% CI 0.45-0.90) compared with no therapy. Warfarin use was associated with a greatly increased risk of ICH (OR 2.82, 95% CI 2.26-3.53) and a moderately increased risk of SAH (OR 1.67, 95% CI 1.15-2.43) compared with no therapy. International normalized ratio values ≥3 carried a marked risk of ICH (OR 7.01, 95% CI 4.10-11.99).\nCONCLUSION: Aspirin is not associated with a risk of ICH compared with no therapy. Chronic low-dose aspirin treatment may have a protective effect on the risk of SAH. Warfarin users in this study cohort were at a much higher risk of ICH than those receiving no therapy, with a marked association with international normalized ratio >3.","container-title":"Neurology","DOI":"10.1212/WNL.0b013e31829e6ffa","ISSN":"1526-632X","issue":"6","journalAbbreviation":"Neurology","language":"eng","note":"PMID: 23843464","page":"566-574","source":"PubMed","title":"Antithrombotic drugs and risk of hemorrhagic stroke in the general population","volume":"81","author":[{"family":"García-Rodríguez","given":"Luis A."},{"family":"Gaist","given":"David"},{"family":"Morton","given":"Jonathan"},{"family":"Cookson","given":"Charlotte"},{"family":"González-Pérez","given":"Antonio"}],"issued":{"date-parts":[["2013",8,6]]}}},{"id":900,"uris":[""],"uri":[""],"itemData":{"id":900,"type":"article-journal","abstract":"Incidence of intracerebral haemorrhage over the past three decades is reported as stable. This disappointing finding is questionable and suggests that any reduction in intracerebral haemorrhage incidence associated with improvements in primary prevention, namely, better control of blood pressure, might have been offset by an increase in cases of intracerebral haemorrhage owing to other factors, including the use of antithrombotic drugs in the ageing population. Therefore, we aimed to analyse trends in intracerebral haemorrhage incidence from 1985 to 2008 in the population-based registry of Dijon, France, taking into consideration the intracerebral haemorrhage location, the effect of age and the changes in the distribution of risk factors and premorbid treatments. Incidence rates were calculated and temporal trends were analysed by age groups (<60, 60-74 and ≥75 years) and intracerebral haemorrhage location (lobar or deep) according to study periods 1985-92, 1993-2000 and 2001-08. Over the 24 years of the study, 3948 patients with first-ever stroke were recorded. Among these, 441 had intracerebral haemorrhage (48.3% male), including 49% lobar, 37% deep, 9% infratentorial and 5% of undetermined location. Mean age at onset increased from 67.3 ± 15.9 years to 74.7 ± 16.7 years over the study period (P < 0.001). Overall crude incidence was 12.4/100,000/year (95% confidence interval: 11.2-13.6) and remained stable over time. However, an ～80% increase in intracerebral haemorrhage incidence among people aged ≥75 years was observed between the first and both second and third study periods, contrasting with a 50% decrease in that in individuals aged <60 years, and stable incidence in those aged 60-74 years. This result was attributed to a 2-fold increase in lobar intracerebral haemorrhage in the elderly, concomitantly with an observed rise in the premorbid use of antithrombotics at this age, whatever the intracerebral haemorrhage location considered. In conclusion, intracerebral haemorrhage profiles have changed in the past 20 years, suggesting that some bleeding-prone vasculopathies in the elderly are more likely to bleed when antithrombotic drugs are used, as illustrated by the rise in the incidence of lobar intracerebral haemorrhage in the elderly, in which cerebral amyloid angiopathy may be strongly implicated. Future research should focus on the impact and management of antithrombotics in patients with intracerebral haemorrhage, which may differ according to the underlying vessel disease.","container-title":"Brain: A Journal of Neurology","DOI":"10.1093/brain/aws349","ISSN":"1460-2156","issue":"Pt 2","journalAbbreviation":"Brain","language":"eng","note":"PMID: 23378220","page":"658-664","source":"PubMed","title":"Intracerebral haemorrhage profiles are changing: results from the Dijon population-based study","title-short":"Intracerebral haemorrhage profiles are changing","volume":"136","author":[{"family":"Béjot","given":"Yannick"},{"family":"Cordonnier","given":"Charlotte"},{"family":"Durier","given":"Jér?me"},{"family":"Aboa-Eboulé","given":"Corine"},{"family":"Rouaud","given":"Olivier"},{"family":"Giroud","given":"Maurice"}],"issued":{"date-parts":[["2013",2]]}}},{"id":69,"uris":[""],"uri":[""],"itemData":{"id":69,"type":"article-journal","abstract":"PURPOSE: The Health Improvement Network (THIN) is a UK healthcare database composed of computerized information from primary care physicians (PCPs). We analyzed the validity of our method for identifying cases of intracerebral hemorrhage (ICH) and subarachnoid hemorrhage (SAH) within THIN and assessed the incidence of these events.\nMETHODS: Patients aged 20-89 years were identified and followed until (i) ICH or SAH was detected, (ii) the patient reached 90 years old (iii) death, or (iv) the end of the study. Computerized patient profiles were reviewed manually; those not discarded became potential cases. A validation study was undertaken in 400 computer-detected cases (333 confirmed as potential cases; 67 discarded). PCPs completed a questionnaire to determine the actual incidence of ICH and SAH among these cases. We also assessed the incidence of ICH and SAH in the total cohort.\nRESULTS: A total of 4330 patients with a READ code suggesting hemorrhagic stroke were identified. Computerized profiles with free-text comments were reviewed manually to identify 3633 potential cases. Responses to the PCP questionnaire were received for 306 potential cases and 63 discarded cases (92% response rate); 82% of potential cases were confirmed. Finally, we identified 3137 cases of hemorrhagic stroke. Crude incidence was 15 per 100,000 person-years for ICH and 11 per 100,000 person-years for SAH; the overall incidence increased sharply with age.\nCONCLUSIONS: Computer detection of cases of hemorrhagic stroke in THIN followed by manual review of clinical profiles is a valid method. The incidence of hemorrhagic stroke increases sharply with age.","container-title":"Pharmacoepidemiology and Drug Safety","DOI":"10.1002/pds.3391","ISSN":"1099-1557","issue":"2","journalAbbreviation":"Pharmacoepidemiol Drug Saf","language":"eng","note":"PMID: 23229888","page":"176-182","source":"PubMed","title":"Incidence of hemorrhagic stroke in the general population: validation of data from The Health Improvement Network","title-short":"Incidence of hemorrhagic stroke in the general population","volume":"22","author":[{"family":"Gaist","given":"David"},{"family":"Wallander","given":"Mari-Ann"},{"family":"González-Pérez","given":"Antonio"},{"family":"García-Rodríguez","given":"Luis Alberto"}],"issued":{"date-parts":[["2013",2]]}}},{"id":615,"uris":[""],"uri":[""],"itemData":{"id":615,"type":"article-journal","abstract":"BACKGROUND: We investigated the association between hemorrhagic stroke and migraine using data from The Health Improvement Network database.\nFINDINGS: We ascertained 1,797 incident cases of intracerebral hemorrhage (ICH) and 1,340 of subarachnoid hemorrhage (SAH). Density-based sampling was used to select 10,000 controls free from hemorrhagic stroke. Using unconditional logistic regression models, we calculated the risk of hemorrhagic stroke associated with migraine, adjusting for age, sex, calendar year, alcohol, body mass index, hypertension, previous cerebrovascular disease, oral contraceptive use, and health services utilization.The risk (odds ratio [OR]) of ICH among migraineurs was 1.2 (95% confidence interval [CI] 0.9-1.5), and of SAH was (1.2, 95% CI 0.9-1.5). The association with ICH was stronger for migraine diagnosed ≥20?years prior to ICH (OR 1.6, 95% CI 1.0-2.4), but not with SAH (OR 1.1, 95% CI 0.6-2.1). In analyses stratified by migraine type and gender, the OR of ICH in women with migraine with aura was 1.7 (95% CI 0.9-3.4) and the corresponding OR of SAH in women was 1.2 (95% CI 0.6-2.3).\nCONCLUSION: No clear increased risk of ICH or SAH was observed in migraineurs.","container-title":"The Journal of Headache and Pain","DOI":"10.1186/1129-2377-15-74","ISSN":"1129-2377","journalAbbreviation":"J Headache Pain","language":"eng","note":"PMID: 25387444\nPMCID: PMC4238312","page":"74","source":"PubMed","title":"Migraine and risk of hemorrhagic stroke: a study based on data from general practice","title-short":"Migraine and risk of hemorrhagic stroke","volume":"15","author":[{"family":"Gaist","given":"David"},{"family":"González-Pérez","given":"Antonio"},{"family":"Ashina","given":"Messoud"},{"family":"Rodríguez","given":"Luis Alberto García"}],"issued":{"date-parts":[["2014",11,11]]}}},{"id":1211,"uris":[""],"uri":[""],"itemData":{"id":1211,"type":"article-journal","abstract":"BACKGROUND: The aim of this study was to explore temporal trends in incidence and case fatality rates of intracerebral hemorrhage (ICH) over the last two decades in a Norwegian municipality.\nMETHODS: Incident cases of primary ICH were registered in the period from 1995 through 2012 in 32,530 participants of the longitudinal population-based Troms? Study. Poisson regression models were used to obtain incidence rates over time in age- and sex-adjusted and age- and sex-specific models. Case fatality rates were calculated and age- and sex-adjusted trends over time were estimated using logistic regression.\nRESULTS: A total of 226 ICHs were registered. The age- and sex-adjusted incidence rate [95% confidence interval (CI)] in the overall population was 0.42 (0.37-0.48) per 1,000 person-years. Age-adjusted incidence rates were 0.53 (0.43-0.62) in men and 0.33 (0.26-0.39) in women. In individuals aged <75 years, the age- and sex-adjusted incidence rate was 0.27 (0.22-0.32) and in individuals aged ≥75 years, it was 2.42 (1.95-2.89) per 1,000 person-years. There was no significant change in incidence rates over time. The incidence rate ratio (95% CI) in the overall population was 0.73 (0.47-1.12) in 2012 compared with 1995. The overall 30-day case fatality (95% CI) was 23.9% (18.3-29.5) and did not change substantially over time [odds ratio in 2012 vs. 1995 = 0.83 (95% CI 0.27-2.52)].\nCONCLUSION: No significant changes in incidence and case fatality rates of ICH were observed during the last two decades.","container-title":"Cerebrovascular Diseases Extra","DOI":"10.1159/000447719","ISSN":"1664-5456","issue":"2","journalAbbreviation":"Cerebrovasc Dis Extra","language":"eng","note":"PMID: 27522404\nPMCID: PMC5040886","page":"40-49","source":"PubMed","title":"Temporal Trends in Incidence and Case Fatality of Intracerebral Hemorrhage: The Troms? Study 1995-2012","title-short":"Temporal Trends in Incidence and Case Fatality of Intracerebral Hemorrhage","volume":"6","author":[{"family":"Carlsson","given":"Maria"},{"family":"Wilsgaard","given":"Tom"},{"family":"Johnsen","given":"Stein Harald"},{"family":"Vangen-L?nne","given":"Anne Merete"},{"family":"L?chen","given":"Maja-Lisa"},{"family":"Nj?lstad","given":"Inger"},{"family":"Mathiesen","given":"Ellisiv B?geberg"}],"issued":{"date-parts":[["2016"]]}}},{"id":975,"uris":[""],"uri":[""],"itemData":{"id":975,"type":"article-journal","abstract":"BACKGROUND: The risks of intracranial haemorrhage (ICH) associated with antithrombotic drugs outside clinical trials are gaining increased attention. The aim of this nationwide study was to investigate the risk of ICH requiring hospital admission in users of antithrombotic drugs.\nMETHODS AND FINDINGS: Data from the Norwegian Patient Registry and Norwegian Prescription Database were linked on an individual level. The primary outcome was incidence rates of ICH associated with use of antithrombotic drugs. Secondary endpoints were risk of ICH and fatal outcome following ICH assessed by Cox models. Among 3,131,270 individuals ≥18 years old observed from 2008 through 2014, there were 729,818 users of antithrombotic medications and 22,111 ICH hospitalizations. Annual crude ICH rates per 100 person-years were 0.076 (95% CI, 0.075-0.077) in non-users and 0.30 (95% CI, 0.30-0.31) in users of antithrombotic medication, with the highest age and sex adjusted rates observed for aspirin-dipyridamole plus clopidogrel (0.44; 95% CI, 0.19-0.69), rivaroxaban plus aspirin (0.36; 95% CI, 0.16-0.56), warfarin plus aspirin (0.34; 95% CI, 0.26-0.43), and warfarin plus aspirin and clopidogrel (0.33; 95% CI, 0.073-0.60). With no antithrombotic medication as reference, the highest adjusted hazard ratios (HR) for ICH were observed for aspirin-dypiridamole plus clopidogrel (6.29; 95% CI 3.71-10.7), warfarin plus aspirin and clopidogrel (4.38; 95% CI 2.71-7.09), rivaroxaban plus aspirin (3.82; 95% CI, 2.46-5.95), and warfarin plus aspirin (3.40; 95% CI, 2.99-3.86). All antithrombotic medication regimens were associated with an increased risk of ICH, except dabigatran monotherapy (HR 1.20; 95% CI, 0.88-1.65) and dabigatran plus aspirin (HR 1.79; 95% CI, 0.96-3.34). Fatal outcome within 90 days was more common in users (2,603 of 8,055) than non-users (3,228 of 14,056) of antithrombotic medication (32.3% vs 23.0%, p<0.001), and was associated with use of warfarin plus aspirin and clopidogrel (HR 2.89; 95% CI, 1.49-5.60), warfarin plus aspirin (HR 1.37; 95% CI, 1.11-1.68), aspirin plus clopidogrel (HR 1.30; 95% CI, 1.05-1.61), and warfarin (HR 1.19; 95% CI, 1.09-1.31). Increased one-year mortality was observed in users of antithrombotic medication following hemorrhagic stroke, subdural hemorrhage, subarachnoid hemorrhage, and traumatic ICH (all p<0.001). Limitations include those inherent to observational studies including the inability to make causal inferences, certain assumptions regarding drug exposure, and the possibility of residual confounding.\nCONCLUSIONS: The real-world incidence rates and risks of ICH were generally higher than reported in randomized controlled trials. There is still major room for improvement in terms of antithrombotic medication safety ( NCT02481011).","container-title":"PloS One","DOI":"10.1371/journal.pone.0202575","ISSN":"1932-6203","issue":"8","journalAbbreviation":"PLoS ONE","language":"eng","note":"PMID: 30138389\nPMCID: PMC6107180","page":"e0202575","source":"PubMed","title":"Risk of intracranial hemorrhage (RICH) in users of oral antithrombotic drugs: Nationwide pharmacoepidemiological study","title-short":"Risk of intracranial hemorrhage (RICH) in users of oral antithrombotic drugs","volume":"13","author":[{"family":"Gulati","given":"Sasha"},{"family":"Solheim","given":"Ole"},{"family":"Carlsen","given":"Sven M."},{"family":"?ie","given":"Lise R."},{"family":"Jensberg","given":"Heidi"},{"family":"Gulati","given":"Agnete M."},{"family":"Madsbu","given":"Mattis A."},{"family":"Giannadakis","given":"Charalampis"},{"family":"Jakola","given":"Asgeir S."},{"family":"Salvesen","given":"?yvind"}],"issued":{"date-parts":[["2018"]]}}},{"id":1204,"uris":[""],"uri":[""],"itemData":{"id":1204,"type":"article-journal","abstract":"BACKGROUND: Accurate and reliable clinical and radiological predictors of intracerebral hemorrhage (ICH) outcomes are needed to optimize treatment of ICH. The aim of this study was to investigate functional outcome and identify predictors of severe disability or death following ICH.\nMATERIALS AND METHODS: Retrospective population-based study of spontaneous ICH. Clinical and radiological data were obtained from electronic medical records, and functional outcome estimated using the modified Rankin Scale (mRS) before ICH and at 3 and 12?months after ICH.\nRESULTS: Four hundred and fifty-two patients were included (mean age 74.8?years, 45.6% females). Proportion of fatal outcome at 1?week was 22.1%, at 3?months 39.2%, and at 12?months 44.9%. Median mRS score before the ICH was 1 (interquartile range [IQR] 2); for survivors at 3?months, it was 5 (IQR 3); and at 12?months, it was 3 (IQR 2). Independent predictors of severe disability (mRS of 5) or death (mRS of 6) were use of oral antithrombotic drugs (OR 2.2, 95% CI 1.3-3.8, p?=?0.04), mRS score before the ICH (OR 1.8, 95% CI 1.4-2.2, p?<?0.001), Glasgow Coma Scale (GCS) on admission (OR 8.3, 95% CI 3.5-19.7, p?<?0.001), hematoma volume >60?ml (OR 4.5, 05% CI 2.0-10.2, p?<?0.001), and intraventricular hematoma extension (OR 1.8, 95% CI 0.8-4.2, p?<?0.001).\nCONCLUSION: Intracerebral hemorrhage is associated with high mortality, and more than one third of survivors end up with severe disability or death 3?months later. Predictors of severe disability or death were use of oral antithrombotic drugs, functional disability prior to ICH, low GCS on admission, larger hematoma volume, and intraventricular hematoma extension.","container-title":"Brain and Behavior","DOI":"10.1002/brb3.1113","ISSN":"2162-3279","issue":"10","journalAbbreviation":"Brain Behav","language":"eng","note":"PMID: 30240164\nPMCID: PMC6192392","page":"e01113","source":"PubMed","title":"Functional outcome and survival following spontaneous intracerebral hemorrhage: A retrospective population-based study","title-short":"Functional outcome and survival following spontaneous intracerebral hemorrhage","volume":"8","author":[{"family":"?ie","given":"Lise R."},{"family":"Madsbu","given":"Mattis A."},{"family":"Solheim","given":"Ole"},{"family":"Jakola","given":"Asgeir S."},{"family":"Giannadakis","given":"Charalampis"},{"family":"Vorhaug","given":"Anders"},{"family":"Padayachy","given":"Llewellyn"},{"family":"Jensberg","given":"Heidi"},{"family":"Dodick","given":"David"},{"family":"Salvesen","given":"?yvind"},{"family":"Gulati","given":"Sasha"}],"issued":{"date-parts":[["2018"]]}}},{"id":1209,"uris":[""],"uri":[""],"itemData":{"id":1209,"type":"article-journal","abstract":"BACKGROUND: Studies on the relationship between temporal trends in risk factors and incidence rates of intracerebral hemorrhage are scarce.\nAIMS: To analyze temporal trends in risk factors and incidence rates of intracerebral hemorrhage using individual data from a population-based study.\nMETHODS: We included 28,167 participants of the Troms? Study enrolled between 1994 and 2008. First-ever intracerebral hemorrhages were registered through 31 December 2013. Hazard ratios (HRs) for intracerebral hemorrhage were analyzed by Cox proportional hazards models, risk factor levels over time by generalized estimating equations, and incidence rate ratios (IRR) by Poisson regression.\nRESULTS: We registered 219 intracerebral hemorrhages. Age, male sex, systolic blood pressure (BP), diastolic BP, and hypertension were associated with intracerebral hemorrhage. Hypertension was more strongly associated with non-lobar intracerebral hemorrhage (HR 5.08, 95% CI 2.86-9.01) than lobar intracerebral hemorrhage (HR 1.91, 95% CI 1.12-3.25). In women, incidence decreased significantly (IRR 0.46, 95% CI 0.23-0.90), driven by a decrease in non-lobar intracerebral hemorrhage. Incidence rates in men remained stable (IRR 1.27, 95% CI 0.69-2.31). BP levels were lower and decreased more steeply in women than in men. The majority with hypertension were untreated, and a high proportion of those treated did not reach treatment goals.\nCONCLUSIONS: We observed a significant decrease in intracerebral hemorrhage incidence in women, but not in men. A steeper BP decrease in women may have contributed to the diverging trends. The high proportion of untreated and sub-optimally treated hypertension calls for improved strategies for prevention of intracerebral hemorrhage.","container-title":"International Journal of Stroke: Official Journal of the International Stroke Society","DOI":"10.1177/1747493018789996","ISSN":"1747-4949","issue":"1","journalAbbreviation":"Int J Stroke","language":"eng","note":"PMID: 30056783","page":"61-68","source":"PubMed","title":"The impact of risk factor trends on intracerebral hemorrhage incidence over the last two decades-The Troms? Study","volume":"14","author":[{"family":"Carlsson","given":"Maria"},{"family":"Wilsgaard","given":"Tom"},{"family":"Johnsen","given":"Stein Harald"},{"family":"Johnsen","given":"Liv-Hege"},{"family":"L?chen","given":"Maja-Lisa"},{"family":"Nj?lstad","given":"Inger"},{"family":"B?geberg Mathiesen","given":"Ellisiv"}],"issued":{"date-parts":[["2019"]]}}},{"id":1202,"uris":[""],"uri":[""],"itemData":{"id":1202,"type":"article-journal","abstract":"BACKGROUND: Intracerebral hemorrhage is a devastating vascular event. Clinical factors prognostic of recurrence facilitating individualized post-bleeding patient management are sparsely described. We aimed to describe incidence of recurrence of intracerebral hemorrhage and explore the prognostic value of 25 clinical characteristics in patients with and without atrial fibrillation.\nMETHODS: Cohort study of patients with incident intracerebral hemorrhage diagnosed from 2003 to 2016 identified using nationwide Danish administrative registries. Results reported as cumulative incidence of intracerebral recurrence accounting for competing risk of death. Univariate and multivariate prognostic factors for recurrence estimated using Cox regression (hazard ratios [HRs], 95% confidence intervals [CI]).\nRESULTS: We identified 9255 patients with incident intracerebral hemorrhage (median age 73?years, 46.6% females, 16% with atrial fibrillation). Five-year risks of recurrence of intracerebral hemorrhage were approximately 10% in the study population, although slightly higher for patients without atrial fibrillation. Prognostic factors for recurrence were broadly similar for patients with and without atrial fibrillation. Age in categories <60?years (reference), age 60-70?years (HR 1.29, 95% CI 1.02-1.64), age 70-80?years (HR 1.59, 95% CI 1.26-2.00), age >80?years (HR 1.19, 95% CI 0.91-1.55), nursing home residency (HR 1.48, 95% CI 1.02-2.13), and Scandinavian Stroke Scale score ('mild' versus 'moderate' (HR 1.40, 95% CI 1.13-1.72) and 'severe' (HR 1.96, 95% CI 1.61-2.39)) were the strongest prognostic factors.\nCONCLUSION: Risk of recurrence of intracerebral hemorrhage after five years was approximately 10%. Clinical characteristics associated with recurrence were few and broadly similar for patients with and without atrial fibrillation, with age and measure of incident bleeding severity, as reflected by Scandinavian Stroke Scale score, being the most important.","container-title":"Thrombosis Research","DOI":"10.1016/j.thromres.2020.03.024","ISSN":"1879-2472","journalAbbreviation":"Thromb. Res.","language":"eng","note":"PMID: 32339765","page":"1-8","source":"PubMed","title":"Incidence and prognostic factors for recurrence of intracerebral hemorrhage in patients with and without atrial fibrillation: A cohort study","title-short":"Incidence and prognostic factors for recurrence of intracerebral hemorrhage in patients with and without atrial fibrillation","volume":"191","author":[{"family":"Overvad","given":"Thure Filskov"},{"family":"Andersen","given":"S?ren Due"},{"family":"Larsen","given":"Torben Bjerregaard"},{"family":"Lip","given":"Gregory Y. H."},{"family":"S?gaard","given":"Mette"},{"family":"Skj?th","given":"Flemming"},{"family":"Nielsen","given":"Peter Br?nnum"}],"issued":{"date-parts":[["2020",4,21]]}}},{"id":1207,"uris":[""],"uri":[""],"itemData":{"id":1207,"type":"article-journal","abstract":"Background and Purpose- It has been suggested that statins increase the risk of intracerebral hemorrhage in individuals with a history of stroke, which has led to a precautionary principle of avoiding statins in patients with prior intracerebral hemorrhage. However, such prescribing reticence may be unfounded and potentially harmful when considering the well-established benefits of statins. This study is so far the largest to explore the statin-associated risk of intracerebral hemorrhage in individuals with prior stroke. Methods- We conducted a population-based, propensity score-matched cohort study using information from Danish national registers. We included all individuals initiating statin treatment after a first-time stroke diagnosis (intracerebral hemorrhage, N=2728 or ischemic stroke, N=52?964) during 2002 to 2016. For up to 10 years of follow-up, they were compared with a 1:5 propensity score-matched group of statin nonusers with the same type of first-time stroke. The difference between groups was measured by adjusted hazard ratios for intracerebral hemorrhage calculated by type of first-time stroke as a function of time since statin initiation. Results- Within the study period, 118 new intracerebral hemorrhages occurred among statin users with prior intracerebral hemorrhage and 319 new intracerebral hemorrhages in users with prior ischemic stroke. The risk of intracerebral hemorrhage was similar for statin users and nonusers when evaluated among those with prior intracerebral hemorrhage, and it was reduced by half in those with prior ischemic stroke. These findings were consistent over time since statin initiation and could not be explained by concomitant initiation of other medications, by dilution of treatment effect (due to changes in exposure status over time), or by healthy initiator bias. Conclusions- This large study found no evidence that statins increase the risk of intracerebral hemorrhage in individuals with prior stroke; perhaps the risk is even lower in the subgroup of individuals with prior ischemic stroke.","container-title":"Stroke","DOI":"10.1161/STROKEAHA.119.027301","ISSN":"1524-4628","issue":"4","journalAbbreviation":"Stroke","language":"eng","note":"PMID: 32114928","page":"1111-1119","source":"PubMed","title":"Statins and Risk of Intracerebral Hemorrhage in Individuals With a History of Stroke","volume":"51","author":[{"family":"Ribe","given":"Anette Riisgaard"},{"family":"Vestergaard","given":"Claus H?strup"},{"family":"Vestergaard","given":"Mogens"},{"family":"Pedersen","given":"Henrik Schou"},{"family":"Prior","given":"Anders"},{"family":"Lietzen","given":"Lone Winther"},{"family":"Brynningsen","given":"Peter Krogh"},{"family":"Fenger-Gr?n","given":"Morten"}],"issued":{"date-parts":[["2020",4]]}}}],"schema":""} 10,21–29 However, to be useful data sources for epidemiologic research, registers must first provide data of sufficiently high quality. While validity is important for all types of research based on register information, for studies of trends in the incidence of diseases, knowledge of the degree of sensitivity of the data is also paramount. ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"vWROxEAw","properties":{"formattedCitation":"\\super 30,31\\nosupersub{}","plainCitation":"30,31","noteIndex":0},"citationItems":[{"id":1276,"uris":[""],"uri":[""],"itemData":{"id":1276,"type":"article-journal","container-title":"Stroke","DOI":"10.1161/STROKEAHA.113.001742","ISSN":"1524-4628","issue":"7","journalAbbreviation":"Stroke","language":"eng","note":"PMID: 23735952","page":"1766-1768","source":"PubMed","title":"Stroke tracked by administrative coding data: is it fair?","title-short":"Stroke tracked by administrative coding data","volume":"44","author":[{"family":"Sacco","given":"Simona"},{"family":"Pistoia","given":"Francesca"},{"family":"Carolei","given":"Antonio"}],"issued":{"date-parts":[["2013",7]]}}},{"id":1268,"uris":[""],"uri":[""],"itemData":{"id":1268,"type":"article-journal","abstract":"Introduction: Administrative hospital diagnostic coding data are increasingly being used in identifying incident and prevalent stroke cases, for outcome audit and for 'big data' research. Validity of administrative coding has varied in previous studies, but little is known about the temporal trends of coding accuracy, which could bias analyses.\nPatients and methods: Using all incident and recurrent strokes in a population-based cohort (Oxford Vascular Study/OXVASC) with multiple sources of ascertainment as the reference, we determined the temporal trends in sensitivity and positive predictive value of hospital diagnostic codes for identifying acute stroke from 2002 to 2017.\nResults: Of 1883 hospitalised strokes, 1341 (71.2%) were correctly identified by coding. Sensitivity of coding improved over time for all strokes (ptrend?=?0.005) and for incident cases (ptrend?=?0.002). Of 1995 apparent stroke admissions identified by International Classification of Disease-10 stroke codes (I60-I68), 1588 (79.6%) used the stroke-specific codes (I60-I61/I63-I64). Positive predictive value was higher with the use of specific codes (83.2% vs. 69.2% for all codes) and highest if combined with the first admission only (88.5%), particularly during more recent time periods (2014-2017?=?90.3%). Of 2254 OXVASC incident strokes, 833 (37.0%) were not hospitalised. Sensitivity of coding increased over time for non-disabling stroke (ptrend?=?0.001), but not for disabling/fatal stroke (ptrend?=?0.40).\nConclusions: Although accuracy of hospital diagnostic coding for identifying acute strokes improved over the last 15?years, residual insensitivity supports linkage to other sources in large epidemiological studies. Moreover, differences in the time trends of coding sensitivity in relation to stroke severity might bias studies of trends in stroke outcome if only administrative coding is used.","container-title":"European Stroke Journal","DOI":"10.1177/2396987319881017","ISSN":"2396-9881","issue":"1","journalAbbreviation":"Eur Stroke J","language":"eng","note":"PMID: 32232167\nPMCID: PMC7092737","page":"26-35","source":"PubMed","title":"Temporal trends in the accuracy of hospital diagnostic coding for identifying acute stroke: A population-based study","title-short":"Temporal trends in the accuracy of hospital diagnostic coding for identifying acute stroke","volume":"5","author":[{"family":"Li","given":"Linxin"},{"family":"Binney","given":"Lucy E."},{"family":"Luengo-Fernandez","given":"Ramon"},{"family":"Silver","given":"Louise E."},{"family":"Rothwell","given":"Peter M."},{"literal":"Oxford Vascular Study"}],"issued":{"date-parts":[["2020",3]]}}}],"schema":""} 30,31 In Denmark, two nationwide registers are of particular use for identifying patients with stroke for research purposes: the Danish Stroke Registry (DSR) and the Danish National Patient Registry (DNPR). The sensitivity of ICH diagnoses in these registers is unknown, and to date only a few studies have examined the validity of ICH diagnoses in DSR ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"ouLMRT3t","properties":{"formattedCitation":"\\super 32\\nosupersub{}","plainCitation":"32","noteIndex":0},"citationItems":[{"id":939,"uris":[""],"uri":[""],"itemData":{"id":939,"type":"article-journal","abstract":"Purpose: The purpose of this study is to establish the validity of intracerebral hemorrhage (ICH) diagnoses in the Danish Stroke Registry (DSR) and the Danish National Patient Registry (DNPR).\nPatients and methods: We estimated the positive predictive value (PPV) of ICH diagnoses for a sample of 500 patients from the DSR (patients recorded under ICH diagnosis) and DNPR (International Classification of Diseases, version 10, code I61) during 2010-2015, using discharge summaries and brain imaging reports (minimal data). We estimated PPVs for any ICH (a-ICH) and spontaneous ICH (s-ICH) alone. Furthermore, we assessed PPVs according to whether patients were recorded in both or only one of the registries. Finally, in a subsample with ICH diagnoses with access to full medical records and original imaging studies (extensive data, n=100), we compared s-ICH diagnosis and hemorrhage location after use of extensive vs minimal data.\nResults: In the DSR, the PPVs were 94% (95% CI, 91%-96%) for a-ICH and 85% (95% CI, 81%-88%) for s-ICH. In the DNPR, the PPVs were 88% (95% CI, 84%-91%) for a-ICH and 75% (95% CI, 70%-79%) for s-ICH. PPVs for s-ICH for patients recorded in both registries, DSR only, and DNPR only were 86% (95% CI, 82-99), 80% (95%CI, 71-87), and 49% (95%CI, 39-59), respectively. Evaluation of extensive vs minimal data verified s-ICH diagnosis in 98% and hemorrhage location in 94%.\nConclusion: The validity of a-ICH diagnoses in DSR and DNPR is sufficiently high to support their use in epidemiologic studies. For s-ICH, validity was high in DSR. In DNPR, s-ICH validity was lower, markedly so for the small subgroup of patients only recorded in this registry. Minimal data including discharge summaries and brain imaging reports were feasible and valid for identifying ICH location.","container-title":"Clinical Epidemiology","DOI":"10.2147/CLEP.S167576","ISSN":"1179-1349","journalAbbreviation":"Clin Epidemiol","language":"eng","note":"PMID: 30123006\nPMCID: PMC6086098","page":"941-948","source":"PubMed","title":"Intracerebral hemorrhage: positive predictive value of diagnosis codes in two nationwide Danish registries","title-short":"Intracerebral hemorrhage","volume":"10","author":[{"family":"Hald","given":"Stine Munk"},{"family":"Kring Sloth","given":"Christine"},{"family":"Hey","given":"Sabine Morris"},{"family":"Madsen","given":"Charlotte"},{"family":"Nguyen","given":"Nina"},{"family":"García Rodríguez","given":"Luis Alberto"},{"family":"Al-Shahi Salman","given":"Rustam"},{"family":"M?ller","given":"S?ren"},{"family":"Poulsen","given":"Frantz Rom"},{"family":"Potteg?rd","given":"Anton"},{"family":"Gaist","given":"David"}],"issued":{"date-parts":[["2018"]]}}}],"schema":""} 32 or DNPR. ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"479CPBUa","properties":{"formattedCitation":"\\super 33\\uc0\\u8211{}36\\nosupersub{}","plainCitation":"33–36","noteIndex":0},"citationItems":[{"id":98,"uris":[""],"uri":[""],"itemData":{"id":98,"type":"article-journal","abstract":"We examined the predictive value of the discharge diagnoses of stroke and transient ischemic attack (TIA) in The National Registry of Patients (NRP) for participants in the Danish cohort study \"Diet, Cancer, and Health.\" We retrieved all probable incident registered cases of stroke and TIA, i.e., ICD-10: I60-69.8, or G45 (n = 581) within the cohort from the NRP. Medical records and hospital discharge summaries were retrieved and reviewed using a standardized form. Overall, 299 of 377 cases (79.3%, 95% CI: 74.9-83.3%) of stroke recorded were confirmed. Subarachnoidal hemorrhage and intracerebral hemorrhage were confirmed in 14 of 29 cases (48.3%, 95% CI: 29.4-67.5%), and 23 of 35 cases (65.7%, 95% CI: 47.8-80.9%), respectively. By contrast, ischemic stroke and unspecified stroke were confirmed in 99 of 113 cases (87.6%, 95% CI: 80.1-93.1%) and 152 of 200 cases (76.0%, 95% CI: 69.5-81.7%), respectively. Among 134 patients with a TIA discharge diagnosis, 60.4% (95% CI: 51.6-68.8%) were confirmed. Discharge diagnoses from emergency rooms had lower overall predictive value (48.8%, 95% CI: 39.9-57.8%) than discharge diagnoses from departments of internal medicine (68.8%, 95% CI: 61.3-75.5%) and departments of neurology or neurosurgery (77.9%, 95% CI: 72.3-82.7%). We conclude that stroke and TIA diagnoses in NRP should be used with caution in epidemiological research because the low predictive value for some diagnostic subgroups may lead to serious misclassification and biased results.","container-title":"Journal of Clinical Epidemiology","ISSN":"0895-4356","issue":"6","journalAbbreviation":"J Clin Epidemiol","language":"eng","note":"PMID: 12063102","page":"602-607","source":"PubMed","title":"Predictive value of stroke and transient ischemic attack discharge diagnoses in The Danish National Registry of Patients","volume":"55","author":[{"family":"Johnsen","given":"S?ren P."},{"family":"Overvad","given":"Kim"},{"family":"S?rensen","given":"Henrik Toft"},{"family":"Tj?nneland","given":"Anne"},{"family":"Husted","given":"Steen E."}],"issued":{"date-parts":[["2002",6]]}}},{"id":96,"uris":[""],"uri":[""],"itemData":{"id":96,"type":"article-journal","abstract":"BACKGROUND: Many registers containing routine medical information have been developed for research and surveillance purposes. In epidemiological research assessment of endpoints is often conducted via registers. In the present study we validated stroke and transient ischemic attack (TIA) diagnoses in the Danish National Register of Patients (DNRP).\nMETHODS: Subjects from a Danish cohort study, the Copenhagen City Heart Study (n = 19,698), were crosslinked with the DNRP. The following International Classification of Disease 10th revision codes were used to identify possible strokes and TIAs: I60-I69 and G45. Two independent raters reviewed all cases. Positive predictive values of stroke, TIA and stroke subtypes were estimated by dividing the confirmed cases by the total number of cases located in the DNRP. Interrater reliability was tested using kappa statistics.\nRESULTS: Of 236 possible cerebrovascular events, 1 in 6 stroke diagnoses did not meet study criteria. The majority of events in the DNRP were registered as unspecified stroke (I64), n = 105 (44%), of which two thirds were diagnosed as ischemic stroke events by the raters. Intracerebral hemorrhage and ischemic stroke had a positive predictive value from 74 to 97%, respectively.\nCONCLUSION: Our results show that the DNRP tends to overestimate the number of cerebrovascular events, while ischemic stroke is underestimated.","container-title":"Neuroepidemiology","DOI":"10.1159/000102143","ISSN":"1423-0208","issue":"3","journalAbbreviation":"Neuroepidemiology","language":"eng","note":"PMID: 17478969","page":"150-154","source":"PubMed","title":"Validity of stroke diagnoses in a National Register of Patients","volume":"28","author":[{"family":"Krarup","given":"Lars-Henrik"},{"family":"Boysen","given":"Gudrun"},{"family":"Janjua","given":"Huma"},{"family":"Prescott","given":"Eva"},{"family":"Truelsen","given":"Thomas"}],"issued":{"date-parts":[["2007"]]}}},{"id":102,"uris":[""],"uri":[""],"itemData":{"id":102,"type":"article-journal","abstract":"BACKGROUND: The validity of the registration of patients in stroke-specific registries has seldom been investigated, nor compared with administrative hospital discharge registries. The objective of this study was to examine the validity of the registration of patients in a stroke-specific registry (The Danish Stroke Registry [DSR]) and a hospital discharge registry (The Danish National Patient Registry [DNRP]).\nMETHODS: Assuming that all patients with stroke were registered in either the DSR, DNRP or both, we first identified a sample of 75 patients registered with stroke in 2009; 25 patients in the DSR, 25 patients in the DNRP, and 25 patients registered in both data sources. Using the medical record as a gold standard, we then estimated the sensitivity and positive predictive value of a stroke diagnosis in the DSR and the DNRP. Secondly, we reviewed 160 medical records for all potential stroke patients discharged from four major neurologic wards within a 7-day period in 2010, and estimated the sensitivity, specificity, positive predictive value, and negative predictive value of the DSR and the DNRP.\nRESULTS: Using the first approach, we found a sensitivity of 97% (worst/best case scenario 92%-99%) in the DSR and 79% (worst/best case scenario 73%-84%) in the DNRP. The positive predictive value was 90% (worst/best case scenario 72%-98%) in the DSR and 79% (worst/best case scenario 62%-88%) in the DNRP. Using the second approach, we found a sensitivity of 91% (95% confidence interval [CI] 81%-96%) and 58% (95% CI 46%-69%) in the DSR and DNRP, respectively. The negative predictive value was 91% (95% CI 83%-96%) in the DSR and 72% (95% CI 62%-80%) in the DNRP. The specificity and positive predictive value did not differ among the registries.\nCONCLUSION: Our data suggest a higher sensitivity in the DSR than the DNRP for acute stroke diagnoses, whereas the positive predictive value was comparable in the two data sources.","container-title":"Clinical Epidemiology","DOI":"10.2147/CLEP.S50449","ISSN":"1179-1349","journalAbbreviation":"Clin Epidemiol","language":"eng","note":"PMID: 24399886\nPMCID: PMC3875194","page":"27-36","source":"PubMed","title":"Registration of acute stroke: validity in the Danish Stroke Registry and the Danish National Registry of Patients","title-short":"Registration of acute stroke","volume":"6","author":[{"family":"Wildenschild","given":"Cathrine"},{"family":"Mehnert","given":"Frank"},{"family":"Thomsen","given":"Reimar Wernich"},{"family":"Iversen","given":"Helle Klingenberg"},{"family":"Vestergaard","given":"Karsten"},{"family":"Ingeman","given":"Annette"},{"family":"Johnsen","given":"S?ren Paaske"}],"issued":{"date-parts":[["2014"]]}}},{"id":611,"uris":[""],"uri":[""],"itemData":{"id":611,"type":"article-journal","abstract":"AIMS: To determine the positive predictive values for stroke discharge diagnoses, including subarachnoidal haemorrhage, intracerebral haemorrhage and cerebral infarction in the Danish National Patient Register.\nMETHODS: Participants in the Danish cohort study Diet, Cancer and Health with a stroke discharge diagnosis in the National Patient Register between 1993 and 2009 were identified and their medical records were retrieved for validation of the diagnoses.\nRESULTS: A total of 3326 records of possible cases of stroke were reviewed. The overall positive predictive value for stroke was 69.3% (95% confidence interval (CI) 67.8-70.9%). The predictive values differed according to hospital characteristics, with the highest predictive value of 87.8% (95% CI 85.5-90.1%) found in departments of neurology and the lowest predictive value of 43.0% (95% CI 37.6-48.5%) found in outpatient clinics.\nCONCLUSIONS: The overall stroke diagnosis in the Danish National Patient Register had a limited predictive value. We therefore recommend the critical use of non-validated register data for research on stroke. The possibility of optimising the predictive values based on more advanced algorithms should be considered.","container-title":"Scandinavian Journal of Public Health","DOI":"10.1177/1403494817716582","ISSN":"1651-1905","issue":"6","journalAbbreviation":"Scand J Public Health","language":"eng","note":"PMID: 28701076","page":"630-636","source":"PubMed","title":"Predictive value of stroke discharge diagnoses in the Danish National Patient Register","volume":"45","author":[{"family":"Lühdorf","given":"Pernille"},{"family":"Overvad","given":"Kim"},{"family":"Schmidt","given":"Erik B."},{"family":"Johnsen","given":"S?ren P."},{"family":"Bach","given":"Flemming W."}],"issued":{"date-parts":[["2017",8]]}}}],"schema":""} 33–36 Table S1 (supplementary material) summarizes the existing studies.We conducted this study with the purpose to provide estimates of the validity of ICH diagnoses in DSR and DNPR and to acquire data on the location of ICH in a large unselected sample of patients with a spontaneous parenchymal hemorrhage. Patients and methodsWe defined any non-traumatic ICH (a-ICH) as a symptomatic event (new headache, altered level of consciousness, or neurological symptoms), with or without new neurological signs, referable to a focal collection of blood within the brain parenchyma seen on brain imaging with signal characteristics consistent with the time of symptom onset. We defined spontaneous ICH (s-ICH), as ICH not attributable to prior trauma, hemorrhagic transformation of an ischemic stroke, or an alternative explanation (eg, tumor or vascular malformation – but not use of antithrombotic drugs). ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"2xShcEbI","properties":{"formattedCitation":"\\super 32,37\\nosupersub{}","plainCitation":"32,37","noteIndex":0},"citationItems":[{"id":939,"uris":[""],"uri":[""],"itemData":{"id":939,"type":"article-journal","abstract":"Purpose: The purpose of this study is to establish the validity of intracerebral hemorrhage (ICH) diagnoses in the Danish Stroke Registry (DSR) and the Danish National Patient Registry (DNPR).\nPatients and methods: We estimated the positive predictive value (PPV) of ICH diagnoses for a sample of 500 patients from the DSR (patients recorded under ICH diagnosis) and DNPR (International Classification of Diseases, version 10, code I61) during 2010-2015, using discharge summaries and brain imaging reports (minimal data). We estimated PPVs for any ICH (a-ICH) and spontaneous ICH (s-ICH) alone. Furthermore, we assessed PPVs according to whether patients were recorded in both or only one of the registries. Finally, in a subsample with ICH diagnoses with access to full medical records and original imaging studies (extensive data, n=100), we compared s-ICH diagnosis and hemorrhage location after use of extensive vs minimal data.\nResults: In the DSR, the PPVs were 94% (95% CI, 91%-96%) for a-ICH and 85% (95% CI, 81%-88%) for s-ICH. In the DNPR, the PPVs were 88% (95% CI, 84%-91%) for a-ICH and 75% (95% CI, 70%-79%) for s-ICH. PPVs for s-ICH for patients recorded in both registries, DSR only, and DNPR only were 86% (95% CI, 82-99), 80% (95%CI, 71-87), and 49% (95%CI, 39-59), respectively. Evaluation of extensive vs minimal data verified s-ICH diagnosis in 98% and hemorrhage location in 94%.\nConclusion: The validity of a-ICH diagnoses in DSR and DNPR is sufficiently high to support their use in epidemiologic studies. For s-ICH, validity was high in DSR. In DNPR, s-ICH validity was lower, markedly so for the small subgroup of patients only recorded in this registry. Minimal data including discharge summaries and brain imaging reports were feasible and valid for identifying ICH location.","container-title":"Clinical Epidemiology","DOI":"10.2147/CLEP.S167576","ISSN":"1179-1349","journalAbbreviation":"Clin Epidemiol","language":"eng","note":"PMID: 30123006\nPMCID: PMC6086098","page":"941-948","source":"PubMed","title":"Intracerebral hemorrhage: positive predictive value of diagnosis codes in two nationwide Danish registries","title-short":"Intracerebral hemorrhage","volume":"10","author":[{"family":"Hald","given":"Stine Munk"},{"family":"Kring Sloth","given":"Christine"},{"family":"Hey","given":"Sabine Morris"},{"family":"Madsen","given":"Charlotte"},{"family":"Nguyen","given":"Nina"},{"family":"García Rodríguez","given":"Luis Alberto"},{"family":"Al-Shahi Salman","given":"Rustam"},{"family":"M?ller","given":"S?ren"},{"family":"Poulsen","given":"Frantz Rom"},{"family":"Potteg?rd","given":"Anton"},{"family":"Gaist","given":"David"}],"issued":{"date-parts":[["2018"]]}}},{"id":651,"uris":[""],"uri":[""],"itemData":{"id":651,"type":"article-journal","abstract":"BACKGROUND AND PURPOSE: The characteristics of intracerebral hemorrhage (ICH) may vary by ICH location because of differences in the distribution of underlying cerebral small vessel diseases. Therefore, we investigated the incidence, characteristics, and outcome of lobar and nonlobar ICH.\nMETHODS: In a population-based, prospective inception cohort study of ICH, we used multiple overlapping sources of case ascertainment and follow-up to identify and validate ICH diagnoses in 2010 to 2011 in an adult population of 695 335.\nRESULTS: There were 128 participants with first-ever primary ICH. The overall incidence of lobar ICH was similar to nonlobar ICH (9.8 [95% confidence interval, 7.7-12.4] versus 8.6 [95% confidence interval, 6.7-11.1] per 100 000 adults/y). At baseline, adults with lobar ICH were more likely to have preceding dementia (21% versus 5%; P=0.01), lower Glasgow Coma Scale scores (median, 13 versus 14; P=0.03), larger ICHs (median, 38 versus 11 mL; P<0.001), subarachnoid extension (57% versus 5%; P<0.001), and subdural extension (15% versus 3%; P=0.02) than those with nonlobar ICH. One-year case fatality was lower after lobar ICH than after nonlobar ICH (adjusted odds ratio for death at 1 year: lobar versus nonlobar ICH 0.21; 95% confidence interval, 0.07-0.63; P=0.006, after adjustment for known predictors of outcome). There were 4 recurrent ICHs, which occurred exclusively in survivors of lobar ICH (annual risk of recurrent ICH after lobar ICH, 11.8%; 95% confidence interval, 4.6%-28.5% versus 0% after nonlobar ICH; log-rank P=0.04).\nCONCLUSIONS: The baseline characteristics and outcome of lobar ICH differ from other locations.","container-title":"Stroke","DOI":"10.1161/STROKEAHA.114.007953","ISSN":"1524-4628","issue":"2","journalAbbreviation":"Stroke","language":"eng","note":"PMID: 25586833","page":"361-368","source":"PubMed","title":"Influence of intracerebral hemorrhage location on incidence, characteristics, and outcome: population-based study","title-short":"Influence of intracerebral hemorrhage location on incidence, characteristics, and outcome","volume":"46","author":[{"family":"Samarasekera","given":"Neshika"},{"family":"Fonville","given":"Arthur"},{"family":"Lerpiniere","given":"Christine"},{"family":"Farrall","given":"Andrew J."},{"family":"Wardlaw","given":"Joanna M."},{"family":"White","given":"Philip M."},{"family":"Smith","given":"Colin"},{"family":"Al-Shahi Salman","given":"Rustam"},{"literal":"Lothian Audit of the Treatment of Cerebral Haemorrhage Collaborators"}],"issued":{"date-parts":[["2015",2]]}}}],"schema":""} 32,37 The above definition is similar to the World Health Organization (WHO) stroke definition, ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"R0q1h2QM","properties":{"formattedCitation":"\\super 38\\nosupersub{}","plainCitation":"38","noteIndex":0},"citationItems":[{"id":135,"uris":[""],"uri":[""],"itemData":{"id":135,"type":"article-journal","container-title":"World Health Organization Technical Report Series","ISSN":"0512-3054","journalAbbreviation":"World Health Organ Tech Rep Ser","language":"eng","note":"PMID: 4998212","page":"1-57","source":"PubMed","title":"Cerebrovascular diseases: prevention, treatment, and rehabilitation. Report of a WHO meeting","title-short":"Cerebrovascular diseases","volume":"469","issued":{"date-parts":[["1971"]]}}}],"schema":""} 38 but in addition allows inclusion of patients based on symptoms (eg, severe sudden onset headache), where imaging supports new onset ICH. Setting and data sourcesWe based this study on data from hospital contacts of residents of the Region of Southern Denmark (RSD; 1.2 million inhabitants), a geographically defined region in Denmark. Patients suspected of a stroke are principally admitted or transferred to one of the four dedicated stroke units at neurology departments in the region, which also hosts a single neurosurgery department. ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"KkTJaOXH","properties":{"formattedCitation":"\\super 32\\nosupersub{}","plainCitation":"32","noteIndex":0},"citationItems":[{"id":939,"uris":[""],"uri":[""],"itemData":{"id":939,"type":"article-journal","abstract":"Purpose: The purpose of this study is to establish the validity of intracerebral hemorrhage (ICH) diagnoses in the Danish Stroke Registry (DSR) and the Danish National Patient Registry (DNPR).\nPatients and methods: We estimated the positive predictive value (PPV) of ICH diagnoses for a sample of 500 patients from the DSR (patients recorded under ICH diagnosis) and DNPR (International Classification of Diseases, version 10, code I61) during 2010-2015, using discharge summaries and brain imaging reports (minimal data). We estimated PPVs for any ICH (a-ICH) and spontaneous ICH (s-ICH) alone. Furthermore, we assessed PPVs according to whether patients were recorded in both or only one of the registries. Finally, in a subsample with ICH diagnoses with access to full medical records and original imaging studies (extensive data, n=100), we compared s-ICH diagnosis and hemorrhage location after use of extensive vs minimal data.\nResults: In the DSR, the PPVs were 94% (95% CI, 91%-96%) for a-ICH and 85% (95% CI, 81%-88%) for s-ICH. In the DNPR, the PPVs were 88% (95% CI, 84%-91%) for a-ICH and 75% (95% CI, 70%-79%) for s-ICH. PPVs for s-ICH for patients recorded in both registries, DSR only, and DNPR only were 86% (95% CI, 82-99), 80% (95%CI, 71-87), and 49% (95%CI, 39-59), respectively. Evaluation of extensive vs minimal data verified s-ICH diagnosis in 98% and hemorrhage location in 94%.\nConclusion: The validity of a-ICH diagnoses in DSR and DNPR is sufficiently high to support their use in epidemiologic studies. For s-ICH, validity was high in DSR. In DNPR, s-ICH validity was lower, markedly so for the small subgroup of patients only recorded in this registry. Minimal data including discharge summaries and brain imaging reports were feasible and valid for identifying ICH location.","container-title":"Clinical Epidemiology","DOI":"10.2147/CLEP.S167576","ISSN":"1179-1349","journalAbbreviation":"Clin Epidemiol","language":"eng","note":"PMID: 30123006\nPMCID: PMC6086098","page":"941-948","source":"PubMed","title":"Intracerebral hemorrhage: positive predictive value of diagnosis codes in two nationwide Danish registries","title-short":"Intracerebral hemorrhage","volume":"10","author":[{"family":"Hald","given":"Stine Munk"},{"family":"Kring Sloth","given":"Christine"},{"family":"Hey","given":"Sabine Morris"},{"family":"Madsen","given":"Charlotte"},{"family":"Nguyen","given":"Nina"},{"family":"García Rodríguez","given":"Luis Alberto"},{"family":"Al-Shahi Salman","given":"Rustam"},{"family":"M?ller","given":"S?ren"},{"family":"Poulsen","given":"Frantz Rom"},{"family":"Potteg?rd","given":"Anton"},{"family":"Gaist","given":"David"}],"issued":{"date-parts":[["2018"]]}}}],"schema":""} 32 All hospitals in Denmark report data in a standardized format to the DNPR. ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"P1wznk3r","properties":{"formattedCitation":"\\super 39\\nosupersub{}","plainCitation":"39","noteIndex":0},"citationItems":[{"id":90,"uris":[""],"uri":[""],"itemData":{"id":90,"type":"article-journal","abstract":"BACKGROUND: The Danish National Patient Registry (DNPR) is one of the world's oldest nationwide hospital registries and is used extensively for research. Many studies have validated algorithms for identifying health events in the DNPR, but the reports are fragmented and no overview exists.\nOBJECTIVES: To review the content, data quality, and research potential of the DNPR.\nMETHODS: We examined the setting, history, aims, content, and classification systems of the DNPR. We searched PubMed and the Danish Medical Journal to create a bibliography of validation studies. We included also studies that were referenced in retrieved papers or known to us beforehand. Methodological considerations related to DNPR data were reviewed.\nRESULTS: During 1977-2012, the DNPR registered 8,085,603 persons, accounting for 7,268,857 inpatient, 5,953,405 outpatient, and 5,097,300 emergency department contacts. The DNPR provides nationwide longitudinal registration of detailed administrative and clinical data. It has recorded information on all patients discharged from Danish nonpsychiatric hospitals since 1977 and on psychiatric inpatients and emergency department and outpatient specialty clinic contacts since 1995. For each patient contact, one primary and optional secondary diagnoses are recorded according to the International Classification of Diseases. The DNPR provides a data source to identify diseases, examinations, certain in-hospital medical treatments, and surgical procedures. Long-term temporal trends in hospitalization and treatment rates can be studied. The positive predictive values of diseases and treatments vary widely (<15%-100%). The DNPR data are linkable at the patient level with data from other Danish administrative registries, clinical registries, randomized controlled trials, population surveys, and epidemiologic field studies - enabling researchers to reconstruct individual life and health trajectories for an entire population.\nCONCLUSION: The DNPR is a valuable tool for epidemiological research. However, both its strengths and limitations must be considered when interpreting research results, and continuous validation of its clinical data is essential.","container-title":"Clinical Epidemiology","DOI":"10.2147/CLEP.S91125","ISSN":"1179-1349","journalAbbreviation":"Clin Epidemiol","language":"eng","note":"PMID: 26604824\nPMCID: PMC4655913","page":"449-490","source":"PubMed","title":"The Danish National Patient Registry: a review of content, data quality, and research potential","title-short":"The Danish National Patient Registry","volume":"7","author":[{"family":"Schmidt","given":"Morten"},{"family":"Schmidt","given":"Sigrun Alba Johannesdottir"},{"family":"Sandegaard","given":"Jakob Lynge"},{"family":"Ehrenstein","given":"Vera"},{"family":"Pedersen","given":"Lars"},{"family":"S?rensen","given":"Henrik Toft"}],"issued":{"date-parts":[["2015"]]}}}],"schema":""} 39 The Danish Stroke Registry (DSR), a clinical database, was established in Denmark in 2003 to monitor the quality of care provided to stroke patients. It is mandatory to report standardized detailed information on all acute admissions for stroke at hospitals in Denmark to the DSR. ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"6nM2mssr","properties":{"formattedCitation":"\\super 40,41\\nosupersub{}","plainCitation":"40,41","noteIndex":0},"citationItems":[{"id":87,"uris":[""],"uri":[""],"itemData":{"id":87,"type":"article-journal","abstract":"OBJECTIVE: In most countries there is no mandatory national system to track the quality of care delivered to the citizens. This paper describes an example of a national indicator project that aims at documenting and improving the quality of care nationwide.\nANALYSIS: The Danish National Indicator Project was established in 2000 as a nationwide multidisciplinary quality improvement project. From 2000 to 2002, disease-specific clinical indicators and standards were developed for six diseases (stroke, hip fracture, schizophrenia, acute gastrointestinal surgery, heart failure, and lung cancer). Indicators and standards have been implemented in all clinical units and departments in Denmark treating patients with the six diseases, and participation is mandatory. All clinical units and departments receive their results every month. National and regional audit processes are organized to explain the results and to prepare implementation of improvements. All results are published in order to inform the public, and to give patients and relatives the opportunity to make informed choices.\nCONCLUSION: The surveillance of health care quality is greatly aided by the use of relevant quantitative indicators. This paper describes how it is possible to organize nationwide monitoring using clinical indicators.","container-title":"International journal for quality in health care: journal of the International Society for Quality in Health Care / ISQua","DOI":"10.1093/intqhc/mzh031","ISSN":"1353-4505","journalAbbreviation":"Int J Qual Health Care","language":"eng","note":"PMID: 15059986","page":"i45-50","source":"PubMed","title":"Nationwide continuous quality improvement using clinical indicators: the Danish National Indicator Project","title-short":"Nationwide continuous quality improvement using clinical indicators","volume":"16 Suppl 1","author":[{"family":"Mainz","given":"Jan"},{"family":"Krog","given":"Birgitte Randrup"},{"family":"Bj?rnshave","given":"Bodil"},{"family":"Bartels","given":"Paul"}],"issued":{"date-parts":[["2004",4]]}}},{"id":85,"uris":[""],"uri":[""],"itemData":{"id":85,"type":"article-journal","abstract":"BACKGROUND: Women live longer than men, yet most studies show that gender has no influence on survival after stroke.\nMETHODS: A registry was started in 2001, with the aim of registering all hospitalized stroke patients in Denmark, and it now holds 39,484 patients of which 48% are female. We studied the influence of gender on post-stroke mortality, from the time of admission through the subsequent years until death or censoring (mean follow-up time: 538 days). All patients underwent an evaluation including stroke severity, computed tomography and cardiovascular risk factors. Independent predictors of death were identified by means of a survival model based on 22,222 individuals with a complete data set.\nRESULTS: Females were older and had severer stroke. Interestingly, the risk of death between genders was time dependent. The female/male stroke mortality rate favoured women from the first day of stroke and remained so during the first month suggesting a female survival advantage. Throughout the second month the rate reversed in favour of men suggesting that women in that period are paying a 'toll' for their initial survival advantage. Hereafter, the rate steadily decreased, and after 4 months women continued to have the same low risk as in the first week.\nCONCLUSIONS: Our study suggests a female superiority in stroke survival competence.","container-title":"Neuroepidemiology","DOI":"10.1159/000112464","ISSN":"1423-0208","issue":"3-4","journalAbbreviation":"Neuroepidemiology","language":"eng","note":"PMID: 18075278\nPMCID: PMC2790769","page":"218-225","source":"PubMed","title":"Sex-related time-dependent variations in post-stroke survival--evidence of a female stroke survival advantage","volume":"29","author":[{"family":"Olsen","given":"Tom Skyh?j"},{"family":"Dehlendorff","given":"Christian"},{"family":"Andersen","given":"Klaus Kaae"}],"issued":{"date-parts":[["2007"]]}}}],"schema":""} 40,41The regional authorities have copies of all hospital electronic medical records (EMRs) in RSD, which can be used for research purposes, provided consent is obtained from the heads of departments involved in patient care. ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"aIOu93hy","properties":{"formattedCitation":"\\super 32\\nosupersub{}","plainCitation":"32","noteIndex":0},"citationItems":[{"id":939,"uris":[""],"uri":[""],"itemData":{"id":939,"type":"article-journal","abstract":"Purpose: The purpose of this study is to establish the validity of intracerebral hemorrhage (ICH) diagnoses in the Danish Stroke Registry (DSR) and the Danish National Patient Registry (DNPR).\nPatients and methods: We estimated the positive predictive value (PPV) of ICH diagnoses for a sample of 500 patients from the DSR (patients recorded under ICH diagnosis) and DNPR (International Classification of Diseases, version 10, code I61) during 2010-2015, using discharge summaries and brain imaging reports (minimal data). We estimated PPVs for any ICH (a-ICH) and spontaneous ICH (s-ICH) alone. Furthermore, we assessed PPVs according to whether patients were recorded in both or only one of the registries. Finally, in a subsample with ICH diagnoses with access to full medical records and original imaging studies (extensive data, n=100), we compared s-ICH diagnosis and hemorrhage location after use of extensive vs minimal data.\nResults: In the DSR, the PPVs were 94% (95% CI, 91%-96%) for a-ICH and 85% (95% CI, 81%-88%) for s-ICH. In the DNPR, the PPVs were 88% (95% CI, 84%-91%) for a-ICH and 75% (95% CI, 70%-79%) for s-ICH. PPVs for s-ICH for patients recorded in both registries, DSR only, and DNPR only were 86% (95% CI, 82-99), 80% (95%CI, 71-87), and 49% (95%CI, 39-59), respectively. Evaluation of extensive vs minimal data verified s-ICH diagnosis in 98% and hemorrhage location in 94%.\nConclusion: The validity of a-ICH diagnoses in DSR and DNPR is sufficiently high to support their use in epidemiologic studies. For s-ICH, validity was high in DSR. In DNPR, s-ICH validity was lower, markedly so for the small subgroup of patients only recorded in this registry. Minimal data including discharge summaries and brain imaging reports were feasible and valid for identifying ICH location.","container-title":"Clinical Epidemiology","DOI":"10.2147/CLEP.S167576","ISSN":"1179-1349","journalAbbreviation":"Clin Epidemiol","language":"eng","note":"PMID: 30123006\nPMCID: PMC6086098","page":"941-948","source":"PubMed","title":"Intracerebral hemorrhage: positive predictive value of diagnosis codes in two nationwide Danish registries","title-short":"Intracerebral hemorrhage","volume":"10","author":[{"family":"Hald","given":"Stine Munk"},{"family":"Kring Sloth","given":"Christine"},{"family":"Hey","given":"Sabine Morris"},{"family":"Madsen","given":"Charlotte"},{"family":"Nguyen","given":"Nina"},{"family":"García Rodríguez","given":"Luis Alberto"},{"family":"Al-Shahi Salman","given":"Rustam"},{"family":"M?ller","given":"S?ren"},{"family":"Poulsen","given":"Frantz Rom"},{"family":"Potteg?rd","given":"Anton"},{"family":"Gaist","given":"David"}],"issued":{"date-parts":[["2018"]]}}}],"schema":""} 32We identified all hospital contacts of residents of RSD recorded in DNPR (data since 2007 made available to us) or DSR (data since 2003, when the register became operational). In DNPR, for the period 1st of January 2007 to 31st of December 2017 we retrieved information on any hospital contacts (ie, inpatient, outpatient, or emergency department contacts) with International Classification of Diseases version 10 (ICD-10) I61 (intracerebral hemorrhage) diagnosis code as the principal diagnostic code (in Danish, ‘aktionsdiagnose’) or in any other diagnostic position. In DSR, stroke diagnoses are recorded as ‘hemorrhagic stroke’ (ie, ICH), ‘ischemic stroke’, or ‘unspecified’. We retrieved data on all hospital contacts recorded under ‘hemorrhagic stroke’ in DSR for the period 1st of January 2003 to 31st of December 2017 using the same residency criteria as above. Within each register sample, we limited records to each patient’s first hospital contact within the years 2009-2017, a period where medical records and brain imaging reports were more likely to be available. We focused on first-ever ICH and therefore excluded patients with records of ICH (DNPR inpatient, outpatient or ED – any diagnostic position, or DSR) predating the study period (ie, before 1st January 2009). Identification of cases for validationWe designed this study similar to a previous validation study we performed in the same region for a shorter time-period (2010-2015) and based on a smaller sample of patients with ICH (n=500 patients). ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"R9SS9S5r","properties":{"formattedCitation":"\\super 32\\nosupersub{}","plainCitation":"32","noteIndex":0},"citationItems":[{"id":939,"uris":[""],"uri":[""],"itemData":{"id":939,"type":"article-journal","abstract":"Purpose: The purpose of this study is to establish the validity of intracerebral hemorrhage (ICH) diagnoses in the Danish Stroke Registry (DSR) and the Danish National Patient Registry (DNPR).\nPatients and methods: We estimated the positive predictive value (PPV) of ICH diagnoses for a sample of 500 patients from the DSR (patients recorded under ICH diagnosis) and DNPR (International Classification of Diseases, version 10, code I61) during 2010-2015, using discharge summaries and brain imaging reports (minimal data). We estimated PPVs for any ICH (a-ICH) and spontaneous ICH (s-ICH) alone. Furthermore, we assessed PPVs according to whether patients were recorded in both or only one of the registries. Finally, in a subsample with ICH diagnoses with access to full medical records and original imaging studies (extensive data, n=100), we compared s-ICH diagnosis and hemorrhage location after use of extensive vs minimal data.\nResults: In the DSR, the PPVs were 94% (95% CI, 91%-96%) for a-ICH and 85% (95% CI, 81%-88%) for s-ICH. In the DNPR, the PPVs were 88% (95% CI, 84%-91%) for a-ICH and 75% (95% CI, 70%-79%) for s-ICH. PPVs for s-ICH for patients recorded in both registries, DSR only, and DNPR only were 86% (95% CI, 82-99), 80% (95%CI, 71-87), and 49% (95%CI, 39-59), respectively. Evaluation of extensive vs minimal data verified s-ICH diagnosis in 98% and hemorrhage location in 94%.\nConclusion: The validity of a-ICH diagnoses in DSR and DNPR is sufficiently high to support their use in epidemiologic studies. For s-ICH, validity was high in DSR. In DNPR, s-ICH validity was lower, markedly so for the small subgroup of patients only recorded in this registry. Minimal data including discharge summaries and brain imaging reports were feasible and valid for identifying ICH location.","container-title":"Clinical Epidemiology","DOI":"10.2147/CLEP.S167576","ISSN":"1179-1349","journalAbbreviation":"Clin Epidemiol","language":"eng","note":"PMID: 30123006\nPMCID: PMC6086098","page":"941-948","source":"PubMed","title":"Intracerebral hemorrhage: positive predictive value of diagnosis codes in two nationwide Danish registries","title-short":"Intracerebral hemorrhage","volume":"10","author":[{"family":"Hald","given":"Stine Munk"},{"family":"Kring Sloth","given":"Christine"},{"family":"Hey","given":"Sabine Morris"},{"family":"Madsen","given":"Charlotte"},{"family":"Nguyen","given":"Nina"},{"family":"García Rodríguez","given":"Luis Alberto"},{"family":"Al-Shahi Salman","given":"Rustam"},{"family":"M?ller","given":"S?ren"},{"family":"Poulsen","given":"Frantz Rom"},{"family":"Potteg?rd","given":"Anton"},{"family":"Gaist","given":"David"}],"issued":{"date-parts":[["2018"]]}}}],"schema":""} 32 Motivated by our previous results, ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"hCt8pK3A","properties":{"formattedCitation":"\\super 32\\nosupersub{}","plainCitation":"32","noteIndex":0},"citationItems":[{"id":939,"uris":[""],"uri":[""],"itemData":{"id":939,"type":"article-journal","abstract":"Purpose: The purpose of this study is to establish the validity of intracerebral hemorrhage (ICH) diagnoses in the Danish Stroke Registry (DSR) and the Danish National Patient Registry (DNPR).\nPatients and methods: We estimated the positive predictive value (PPV) of ICH diagnoses for a sample of 500 patients from the DSR (patients recorded under ICH diagnosis) and DNPR (International Classification of Diseases, version 10, code I61) during 2010-2015, using discharge summaries and brain imaging reports (minimal data). We estimated PPVs for any ICH (a-ICH) and spontaneous ICH (s-ICH) alone. Furthermore, we assessed PPVs according to whether patients were recorded in both or only one of the registries. Finally, in a subsample with ICH diagnoses with access to full medical records and original imaging studies (extensive data, n=100), we compared s-ICH diagnosis and hemorrhage location after use of extensive vs minimal data.\nResults: In the DSR, the PPVs were 94% (95% CI, 91%-96%) for a-ICH and 85% (95% CI, 81%-88%) for s-ICH. In the DNPR, the PPVs were 88% (95% CI, 84%-91%) for a-ICH and 75% (95% CI, 70%-79%) for s-ICH. PPVs for s-ICH for patients recorded in both registries, DSR only, and DNPR only were 86% (95% CI, 82-99), 80% (95%CI, 71-87), and 49% (95%CI, 39-59), respectively. Evaluation of extensive vs minimal data verified s-ICH diagnosis in 98% and hemorrhage location in 94%.\nConclusion: The validity of a-ICH diagnoses in DSR and DNPR is sufficiently high to support their use in epidemiologic studies. For s-ICH, validity was high in DSR. In DNPR, s-ICH validity was lower, markedly so for the small subgroup of patients only recorded in this registry. Minimal data including discharge summaries and brain imaging reports were feasible and valid for identifying ICH location.","container-title":"Clinical Epidemiology","DOI":"10.2147/CLEP.S167576","ISSN":"1179-1349","journalAbbreviation":"Clin Epidemiol","language":"eng","note":"PMID: 30123006\nPMCID: PMC6086098","page":"941-948","source":"PubMed","title":"Intracerebral hemorrhage: positive predictive value of diagnosis codes in two nationwide Danish registries","title-short":"Intracerebral hemorrhage","volume":"10","author":[{"family":"Hald","given":"Stine Munk"},{"family":"Kring Sloth","given":"Christine"},{"family":"Hey","given":"Sabine Morris"},{"family":"Madsen","given":"Charlotte"},{"family":"Nguyen","given":"Nina"},{"family":"García Rodríguez","given":"Luis Alberto"},{"family":"Al-Shahi Salman","given":"Rustam"},{"family":"M?ller","given":"S?ren"},{"family":"Poulsen","given":"Frantz Rom"},{"family":"Potteg?rd","given":"Anton"},{"family":"Gaist","given":"David"}],"issued":{"date-parts":[["2018"]]}}}],"schema":""} 32 and aiming to identify reliable algorithms that would enable optimal use of the register data, we designed the present validation study to calculate PPV of the DSR and DNPR when used independently, or in combination. The researchers that performed the assessments described below were blinded with regard to the register source.We identified information on patients with a possible first-ever diagnosis of ICH as follows. We retrieved data on all patients recorded under ICH diagnoses in the DNPR, or the DSR in 2009-2017, as described above. To minimize capture of re-admissions for the same ICH event, we identified the first hospital contact during the period. Furthermore, we only included patients that were aged 20+ years at the time of the first hospital contact as DSR only records data on adult patients. We merged the resulting data and classified patients into three mutually exclusive groups: (i) recorded in both registries, (ii) recorded in DNPR only; and (iii) recorded in DSR only. We only classified patients as recorded in both registries, if hospital contact dates in the two registries were separated by no more than 7 days, in order to enhance the likelihood of studying the same event. For patients identified in the DNPR, in addition to the contact on the index date, we also identified all other hospital contacts (ie, admission, outpatient or emergency department (ED)) with a diagnosis code of ICH that we considered to belong to the same episode of ICH, ie, consecutive contacts separated by a gap of no more than 7 days. Based on this information, we classified patients recorded by DNPR by patterns of contact as follows: (a) inpatient with ICH discharge code in primary diagnostic position (regardless of ED/outpatient contacts); (b) inpatient with ICH discharge code in diagnostic position other than primary (regardless of ED/outpatient contacts); (c) outpatient only or ED only, any diagnostic position. Data on all patients, identified as outlined above, were validated based on information from discharge records and brain scan reports. These documents were mainly (63%) provided to us in electronic form by the regional authorities, which hold copies of all hospital EMRs in RSD. All hospitals in RSD use the same EMR system that was gradually implemented in the years 2008 to 2015. For contacts with no record in the centralized copy of EMRs (mainly records predating the introduction of the EMR system), we requested manually retrieved copies of discharge summaries and brain scan reports from the hospital departments involved. We were granted permission to retrieve data as outlined by all heads of departments involved. In anticipation of the logistic difficulties involved, we did not retrieve information on patients residing in RSD who were only recorded with ICH diagnoses at hospitals located out of the region or abroad (<2% of cases). Based on previous experience, ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"Y9ImMTPK","properties":{"formattedCitation":"\\super 32\\nosupersub{}","plainCitation":"32","noteIndex":0},"citationItems":[{"id":939,"uris":[""],"uri":[""],"itemData":{"id":939,"type":"article-journal","abstract":"Purpose: The purpose of this study is to establish the validity of intracerebral hemorrhage (ICH) diagnoses in the Danish Stroke Registry (DSR) and the Danish National Patient Registry (DNPR).\nPatients and methods: We estimated the positive predictive value (PPV) of ICH diagnoses for a sample of 500 patients from the DSR (patients recorded under ICH diagnosis) and DNPR (International Classification of Diseases, version 10, code I61) during 2010-2015, using discharge summaries and brain imaging reports (minimal data). We estimated PPVs for any ICH (a-ICH) and spontaneous ICH (s-ICH) alone. Furthermore, we assessed PPVs according to whether patients were recorded in both or only one of the registries. Finally, in a subsample with ICH diagnoses with access to full medical records and original imaging studies (extensive data, n=100), we compared s-ICH diagnosis and hemorrhage location after use of extensive vs minimal data.\nResults: In the DSR, the PPVs were 94% (95% CI, 91%-96%) for a-ICH and 85% (95% CI, 81%-88%) for s-ICH. In the DNPR, the PPVs were 88% (95% CI, 84%-91%) for a-ICH and 75% (95% CI, 70%-79%) for s-ICH. PPVs for s-ICH for patients recorded in both registries, DSR only, and DNPR only were 86% (95% CI, 82-99), 80% (95%CI, 71-87), and 49% (95%CI, 39-59), respectively. Evaluation of extensive vs minimal data verified s-ICH diagnosis in 98% and hemorrhage location in 94%.\nConclusion: The validity of a-ICH diagnoses in DSR and DNPR is sufficiently high to support their use in epidemiologic studies. For s-ICH, validity was high in DSR. In DNPR, s-ICH validity was lower, markedly so for the small subgroup of patients only recorded in this registry. Minimal data including discharge summaries and brain imaging reports were feasible and valid for identifying ICH location.","container-title":"Clinical Epidemiology","DOI":"10.2147/CLEP.S167576","ISSN":"1179-1349","journalAbbreviation":"Clin Epidemiol","language":"eng","note":"PMID: 30123006\nPMCID: PMC6086098","page":"941-948","source":"PubMed","title":"Intracerebral hemorrhage: positive predictive value of diagnosis codes in two nationwide Danish registries","title-short":"Intracerebral hemorrhage","volume":"10","author":[{"family":"Hald","given":"Stine Munk"},{"family":"Kring Sloth","given":"Christine"},{"family":"Hey","given":"Sabine Morris"},{"family":"Madsen","given":"Charlotte"},{"family":"Nguyen","given":"Nina"},{"family":"García Rodríguez","given":"Luis Alberto"},{"family":"Al-Shahi Salman","given":"Rustam"},{"family":"M?ller","given":"S?ren"},{"family":"Poulsen","given":"Frantz Rom"},{"family":"Potteg?rd","given":"Anton"},{"family":"Gaist","given":"David"}],"issued":{"date-parts":[["2018"]]}}}],"schema":""} 32 to ensure coverage of transfers between units (eg, from ED to stroke unit, or from one hospital to another), and of further work-up for secondary causes (eg, follow up imaging after incident ICH), we requested discharge records and brain imaging study reports for a period spanning one week before to five months after the hospital contact date of the index event. Nine study physicians –supervised by two neurologists and a specialist in radiology with a special interest in stroke – assessed this information and abstracted data to a structured form. Information collected included ICH diagnosis verified, whether it was s-ICH, and location of s-ICH. We classified ICH into ‘single ICH’ or ‘multiple ICH’ (more than one concurrent ICH described in brain scan report). We classified ICH location based on a slightly modified version of the criteria employed in a previous population-based study ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"q4NKE1Dr","properties":{"formattedCitation":"\\super 37\\nosupersub{}","plainCitation":"37","noteIndex":0},"citationItems":[{"id":651,"uris":[""],"uri":[""],"itemData":{"id":651,"type":"article-journal","abstract":"BACKGROUND AND PURPOSE: The characteristics of intracerebral hemorrhage (ICH) may vary by ICH location because of differences in the distribution of underlying cerebral small vessel diseases. Therefore, we investigated the incidence, characteristics, and outcome of lobar and nonlobar ICH.\nMETHODS: In a population-based, prospective inception cohort study of ICH, we used multiple overlapping sources of case ascertainment and follow-up to identify and validate ICH diagnoses in 2010 to 2011 in an adult population of 695 335.\nRESULTS: There were 128 participants with first-ever primary ICH. The overall incidence of lobar ICH was similar to nonlobar ICH (9.8 [95% confidence interval, 7.7-12.4] versus 8.6 [95% confidence interval, 6.7-11.1] per 100 000 adults/y). At baseline, adults with lobar ICH were more likely to have preceding dementia (21% versus 5%; P=0.01), lower Glasgow Coma Scale scores (median, 13 versus 14; P=0.03), larger ICHs (median, 38 versus 11 mL; P<0.001), subarachnoid extension (57% versus 5%; P<0.001), and subdural extension (15% versus 3%; P=0.02) than those with nonlobar ICH. One-year case fatality was lower after lobar ICH than after nonlobar ICH (adjusted odds ratio for death at 1 year: lobar versus nonlobar ICH 0.21; 95% confidence interval, 0.07-0.63; P=0.006, after adjustment for known predictors of outcome). There were 4 recurrent ICHs, which occurred exclusively in survivors of lobar ICH (annual risk of recurrent ICH after lobar ICH, 11.8%; 95% confidence interval, 4.6%-28.5% versus 0% after nonlobar ICH; log-rank P=0.04).\nCONCLUSIONS: The baseline characteristics and outcome of lobar ICH differ from other locations.","container-title":"Stroke","DOI":"10.1161/STROKEAHA.114.007953","ISSN":"1524-4628","issue":"2","journalAbbreviation":"Stroke","language":"eng","note":"PMID: 25586833","page":"361-368","source":"PubMed","title":"Influence of intracerebral hemorrhage location on incidence, characteristics, and outcome: population-based study","title-short":"Influence of intracerebral hemorrhage location on incidence, characteristics, and outcome","volume":"46","author":[{"family":"Samarasekera","given":"Neshika"},{"family":"Fonville","given":"Arthur"},{"family":"Lerpiniere","given":"Christine"},{"family":"Farrall","given":"Andrew J."},{"family":"Wardlaw","given":"Joanna M."},{"family":"White","given":"Philip M."},{"family":"Smith","given":"Colin"},{"family":"Al-Shahi Salman","given":"Rustam"},{"literal":"Lothian Audit of the Treatment of Cerebral Haemorrhage Collaborators"}],"issued":{"date-parts":[["2015",2]]}}}],"schema":""} 37: 1) ‘deep ICH’ (single supratentorial deep ICH, or multiple ICHs in solely deep locations); 2) ‘infratentorial ICH’ (single infratentorial ICH, or multiple ICHs in solely infratentorial locations, or infratentorial ICH combined with deep ICH); 3) ‘large unclassifiable ICH’; 4) ‘isolated intraventricular ICH’; 5) ‘insufficient information to classify’; and 6) ‘lobar ICH’ (all other, ie, ICH locations not included in categories 1-5). Full medical records were retrieved in cases of doubt regarding the diagnosis.Study data were collected and managed using REDCap electronic data capture tools hosted at Odense Patient data Explorative Network (OPEN). ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"4lLlKM9A","properties":{"formattedCitation":"\\super 42,43\\nosupersub{}","plainCitation":"42,43","noteIndex":0},"citationItems":[{"id":1261,"uris":[""],"uri":[""],"itemData":{"id":1261,"type":"article-journal","abstract":"Research electronic data capture (REDCap) is a novel workflow methodology and software solution designed for rapid development and deployment of electronic data capture tools to support clinical and translational research. We present: (1) a brief description of the REDCap metadata-driven software toolset; (2) detail concerning the capture and use of study-related metadata from scientific research teams; (3) measures of impact for REDCap; (4) details concerning a consortium network of domestic and international institutions collaborating on the project; and (5) strengths and limitations of the REDCap system. REDCap is currently supporting 286 translational research projects in a growing collaborative network including 27 active partner institutions.","container-title":"Journal of Biomedical Informatics","DOI":"10.1016/j.jbi.2008.08.010","ISSN":"1532-0480","issue":"2","journalAbbreviation":"J Biomed Inform","language":"eng","note":"PMID: 18929686\nPMCID: PMC2700030","page":"377-381","source":"PubMed","title":"Research electronic data capture (REDCap)--a metadata-driven methodology and workflow process for providing translational research informatics support","volume":"42","author":[{"family":"Harris","given":"Paul A."},{"family":"Taylor","given":"Robert"},{"family":"Thielke","given":"Robert"},{"family":"Payne","given":"Jonathon"},{"family":"Gonzalez","given":"Nathaniel"},{"family":"Conde","given":"Jose G."}],"issued":{"date-parts":[["2009",4]]}}},{"id":1264,"uris":[""],"uri":[""],"itemData":{"id":1264,"type":"article-journal","abstract":"The Research Electronic Data Capture (REDCap) data management platform was developed in 2004 to address an institutional need at Vanderbilt University, then shared with a limited number of adopting sites beginning in 2006. Given bi-directional benefit in early sharing experiments, we created a broader consortium sharing and support model for any academic, non-profit, or government partner wishing to adopt the software. Our sharing framework and consortium-based support model have evolved over time along with the size of the consortium (currently more than 3200 REDCap partners across 128 countries). While the \"REDCap Consortium\" model represents only one example of how to build and disseminate a software platform, lessons learned from our approach may assist other research institutions seeking to build and disseminate innovative technologies.","container-title":"Journal of Biomedical Informatics","DOI":"10.1016/j.jbi.2019.103208","ISSN":"1532-0480","journalAbbreviation":"J Biomed Inform","language":"eng","note":"PMID: 31078660\nPMCID: PMC7254481","page":"103208","source":"PubMed","title":"The REDCap consortium: Building an international community of software platform partners","title-short":"The REDCap consortium","volume":"95","author":[{"family":"Harris","given":"Paul A."},{"family":"Taylor","given":"Robert"},{"family":"Minor","given":"Brenda L."},{"family":"Elliott","given":"Veida"},{"family":"Fernandez","given":"Michelle"},{"family":"O'Neal","given":"Lindsay"},{"family":"McLeod","given":"Laura"},{"family":"Delacqua","given":"Giovanni"},{"family":"Delacqua","given":"Francesco"},{"family":"Kirby","given":"Jacqueline"},{"family":"Duda","given":"Stephany N."},{"literal":"REDCap Consortium"}],"issued":{"date-parts":[["2019"]]}}}],"schema":""} 42,43Statistical analysesWe computed PPVs of registry diagnoses of ICH for each of the sources (DNPR vs DSR), and for each of the three groups (ie, DNPR & DSR, DNPR only, or DSR only), as proportions of each parameter confirmed by the verification process described above. We computed the sensitivity of the registers when used as independent sources (ie, either DNPR or DSR) as the proportion of number of cases verified by each source divided by the total number of cases verified in either of the registers. We used the Wilson score method to estimate 95% confidence intervals for all proportions. ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"lFv0iwfP","properties":{"formattedCitation":"\\super 44\\nosupersub{}","plainCitation":"44","noteIndex":0},"citationItems":[{"id":1279,"uris":[""],"uri":[""],"itemData":{"id":1279,"type":"article-journal","container-title":"Journal of the American Statistical Association","page":"209-212","title":"Probable inference, the law of succession, and statistical inference","volume":"22","author":[{"family":"Wilson","given":"EB"}],"issued":{"date-parts":[["1927"]]}}}],"schema":""} 44 We also calculated a chi-square statistic for the trend ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"9nlBPdvN","properties":{"formattedCitation":"\\super 45\\nosupersub{}","plainCitation":"45","noteIndex":0},"citationItems":[{"id":1280,"uris":[""],"uri":[""],"itemData":{"id":1280,"type":"article","note":"Statistical Software Components S426101","publisher":"Boston College Deparment of Economics","title":"PTREND: Stata module for trend analysis for proportions.","URL":"","author":[{"family":"Royston","given":"P"}],"accessed":{"date-parts":[["2020",6,4]]},"issued":{"date-parts":[["2014"]]}}}],"schema":""} 45 (regression) of sensitivity estimates across the three time periods (2009-2011; 2012-2014; 2015-2017) and age-groups (<65; 65-74; ≥75 years). All analyses were performed using Stata 16.1 (Stata Corp, TX). The study was approved by the Danish Data Protection Agency (Approval ID 15/53398) and the Danish Health and Medicines Authority (Approval ID 3-3013-942/1).ResultsA total of 2,590 and 4,176 discharges were recorded under ICH diagnosis codes in DSR and DNPR, respectively. Cross-linkage of the data from the two registries resulted in 4,149 patients, after exclusion of patients younger than 20 years (n=52), and patients who only had been registered with ICH diagnoses at hospitals outside the region (n=78). Exclusion of a further 193 patients, where we could not obtain the medical records, resulted in a total study population of 3,956 patients (Figure 1). In all, 59.6% were recorded in both registries, 2.2% in DSR only, and 38.3% in DNPR only. The percentage of untraced medical record information in the three categories was 4.5 % for DSR & DNPR, 7.5% (n=7) for DSR only, and 4.7% for DNPR only.For patients included in the study, we retrieved both discharge letters and brain scan reports in 93%, discharge letters only in 1%, and brain scan reports only in 6% of cases. In a few cases (n=94), the discharge letter and/or brain scan report were deemed insufficient to reach a diagnosis, in which case we retrieved full medical records or re-evaluated original brain scans. The diagnosis of a-ICH could not be verified in a total of 1,192 cases (30.1%). Close to half of the patients in this group (n=528) had suffered an ICH that did not fulfill study criteria (eg, ICH due to trauma), and another third of patients had intracranial hemorrhages other than ICH (n=396) (Table 1). The corresponding percentages by registry source (ie, DSR / DNPR inpatient, primary coding position) were (a) ICH that did not fulfill study criteria 56.7% / 45.8%; and (b) intracranial hemorrhage other than ICH 35.4% / 23.3%.Among patients with verified a-ICH (n=2,764), an underlying cause was found in 225 patients (most frequently (92%) hemorrhages in brain tumors, or from arteriovenous malformations or cavernous hemangiomas (Table 1)), leaving a total of 2,539 patients with s-ICH. We compared the earliest date of contact with a code of ICH according to registry data (registry date) with the date of onset of ICH as assessed by the study physician who evaluated the retrieved medical record information. For cases with verified a-ICH, the onset date was within 7 days of the registry date in 93% of cases (the two dates were identical in 82% of cases), while it differed by more than a week in 2.6% of cases only; information on date of onset could not be accurately established based on medical record information in 4.3% of cases, mostly due to vague wording (eg, “symptoms for a few days with subacute ICH changes on brain scan” with no mention of exact date of onset). For the majority of patients with a-ICH, the initial scan was a computed tomography (CT) of the brain (CTC) (94%), while for 4% of patients the initial scan was CT-angiography (CTA), or brain magnetic resonance imaging (MRI) (1.2%). In 0.8% of a-ICH patients the type of brain scan was unknown as the brain scan report was not traced and the discharge letter although referring to the brain imaging result did not specify the type of scan performed. Initial brain scan reports of patients with a-ICH frequently described intraventricular spread of the hematoma (37%), a known poor prognostic sign, and signs indicative of increased intracranial pressure (deviation of midline structures 32%, presence of hydrocephalus 10%, herniation 3.2%). Among patients with s-ICH, further imaging work-up was performed in 49.5% of cases (n=1,256); in 24% of cases in the form of brain MRI, CTA or both. The percentage of patients with s-ICH that had been further investigated with imaging was higher in younger patients (age ≤55 years: 64%; age 56+years: 48%). Our definition of ICH differed slightly from the WHO definition, in that we also included patients with non-focal symptoms or symptoms lasting less than 24 hours if brain imaging revealed acute parenchymal hemorrhage. Cases verified according to our criteria would also have been classified as such according to WHO criteria in 96.7% of cases for a-ICH and 96.4% of cases for s-ICH.Positive predictive values of ICH diagnosis codeIn DSR, the PPV for a-ICH diagnosis was 86.5% (95%CI, 85.1-87.8) and for s-ICH 81.8% (95%CI, 80.2-83.3). The corresponding values for DNPR were higher for inpatient codes with ICH in the primary diagnostic position, compared with inpatient codes with ICH in coding position other than primary for both a-ICH, (76.2%; 95% CI, 74.7-77.6 vs 49.5%; 95%CI, 45.6-53.4) and s-ICH (70.2%; 95%CI, 68.6-71.8 vs 43.7%; 95%CI, 39.9-47.6) (Table 2). In analyses where we combined data from the two sources, the highest PPV was observed among patients concurrently recorded in DSR and DNPR–inpatient primary diagnostic position (a-ICH: 88.6%; 95%CI, 87.1-89.9 & s-ICH: 83.7%; 95%CI, 82.1-85.2) and the lowest PPV among patients only recorded in DNPR with ICH codes for outpatient or ED contacts (7.4%; 95%CI, 3.2-16.1 for both a-ICH and s-ICH) (Table 3). Year of admission, age, and sex had little impact on PPV of a-ICH and s-ICH in DSR or DNPR–inpatient primary diagnostic position (Table 4). Sensitivity of ICH diagnosis codeThe sensitivity in DSR for a-ICH was 76.4% (95%CI, 74.8-78.0) and for s-ICH 78.7% (95%CI, 77.1-80.2); for DNPR–inpatient primary diagnostic position the sensitivity for a-ICH was 87.3% (95%CI, 86.0-88.5) and for s-ICH 87.7% (95%CI, 86.3-88.9). The sensitivity in DSR declined over time for both a-ICH and s-ICH (eg, s-ICH: 2009-2011: 85.6%, 95%CI; 83.0-87.9 vs 2012-2014: 78.2%; 95%CI, 75.2-80.9% vs 2015-2017: 73.3%; 95%CI, 70.4-76.0). Sensitivity in DSR was higher in older patients for both a-ICH and s-ICH (eg, s-ICH: <64 years: 74.5%; 95%CI, 71.1-77.7 vs 65-74 years: 79.2%; 95%CI, 76.0-82.1 vs 75+ years 80.6%; 95%CI, 78.3-82.7) (Table 4). When stratified across both age (<75 years vs ≥75 years) and sex strata, sensitivity remained high for DNPR; for DSR, sensitivity estimates were highest for men aged 75+ years (91% in 2009-2011; 80% in 2012-2014; 82% in 2015-2017) and lowest for women younger than 75 years (82% in 2009-2011; 72% in 2012-2014; 64% in 2015-2017), the overall pattern being compatible with a decline in sensitivity over time across all strata (Table 5). Patients with untraceable medical recordsWe excluded 193 patients with untraceable medical records (untraced cases) from the above analyses. The proportion of untraced cases declined during the study period (2009-2011: 116 [60%]; 2012-2014: 57 [30%]; 2015-2017: 20 [10%]) (Table 6). The proportion of untraced cases among inpatients in DSR and DNPR also varied by time period, while similar in analyses by age and sex (Table 7). The majority of untraced cases before 2015 had received ICH diagnosis codes as inpatients and were recorded in both DSR and DNPR, while in the last 3-year part of the study period, the small number of untraced cases primarily comprised hospital contacts other than inpatient (Table 7). The higher number of untraced cases before 2015 was primarily due to paper-based medical records (ie, predating the EMR system) no longer being available in the archives of some hospitals in the catchment area.Location of s-ICHAmong the 2,539 cases of s-ICH, 2,430 had a single ICH and 109 multiple concurrent ICH (Table 8). The location of the hemorrhage in s-ICH (single or multiple) was lobar (39.0%), deep (33.6%), infratentorial (13.2%), large unclassifiable (11.0%), or isolated intraventricular hemorrhage (1.9%); we could not classify the location in 1.3% of s-ICH due to insufficient information (1.2% of single ICH and 4.6% of multiple ICH cases). DiscussionIn this large study with data from an entire Danish region for the years 2009-2017, we found a high validity of a-ICH diagnosis in DSR and DNPR–inpatient primary coding position using each of these registries as a single data source. For s-ICH, validity was also high in DSR, but was lower in DNPR. PPVs of patients recorded in both registries were higher, compared with PPVs based on patients only recorded in one of the registries. The sensitivity of DNPR was higher than that of DSR, with the latter exhibiting some degree of variation by age of patients (ie, higher sensitivity in older patients) and time-period (ie, lower sensitivity in later compared with earlier part of study period).Four studies have reported data on the validity of ICH diagnoses in DNPR (Table S1). ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"ILOpNkM1","properties":{"formattedCitation":"\\super 32\\uc0\\u8211{}34,36\\nosupersub{}","plainCitation":"32–34,36","noteIndex":0},"citationItems":[{"id":939,"uris":[""],"uri":[""],"itemData":{"id":939,"type":"article-journal","abstract":"Purpose: The purpose of this study is to establish the validity of intracerebral hemorrhage (ICH) diagnoses in the Danish Stroke Registry (DSR) and the Danish National Patient Registry (DNPR).\nPatients and methods: We estimated the positive predictive value (PPV) of ICH diagnoses for a sample of 500 patients from the DSR (patients recorded under ICH diagnosis) and DNPR (International Classification of Diseases, version 10, code I61) during 2010-2015, using discharge summaries and brain imaging reports (minimal data). We estimated PPVs for any ICH (a-ICH) and spontaneous ICH (s-ICH) alone. Furthermore, we assessed PPVs according to whether patients were recorded in both or only one of the registries. Finally, in a subsample with ICH diagnoses with access to full medical records and original imaging studies (extensive data, n=100), we compared s-ICH diagnosis and hemorrhage location after use of extensive vs minimal data.\nResults: In the DSR, the PPVs were 94% (95% CI, 91%-96%) for a-ICH and 85% (95% CI, 81%-88%) for s-ICH. In the DNPR, the PPVs were 88% (95% CI, 84%-91%) for a-ICH and 75% (95% CI, 70%-79%) for s-ICH. PPVs for s-ICH for patients recorded in both registries, DSR only, and DNPR only were 86% (95% CI, 82-99), 80% (95%CI, 71-87), and 49% (95%CI, 39-59), respectively. Evaluation of extensive vs minimal data verified s-ICH diagnosis in 98% and hemorrhage location in 94%.\nConclusion: The validity of a-ICH diagnoses in DSR and DNPR is sufficiently high to support their use in epidemiologic studies. For s-ICH, validity was high in DSR. In DNPR, s-ICH validity was lower, markedly so for the small subgroup of patients only recorded in this registry. Minimal data including discharge summaries and brain imaging reports were feasible and valid for identifying ICH location.","container-title":"Clinical Epidemiology","DOI":"10.2147/CLEP.S167576","ISSN":"1179-1349","journalAbbreviation":"Clin Epidemiol","language":"eng","note":"PMID: 30123006\nPMCID: PMC6086098","page":"941-948","source":"PubMed","title":"Intracerebral hemorrhage: positive predictive value of diagnosis codes in two nationwide Danish registries","title-short":"Intracerebral hemorrhage","volume":"10","author":[{"family":"Hald","given":"Stine Munk"},{"family":"Kring Sloth","given":"Christine"},{"family":"Hey","given":"Sabine Morris"},{"family":"Madsen","given":"Charlotte"},{"family":"Nguyen","given":"Nina"},{"family":"García Rodríguez","given":"Luis Alberto"},{"family":"Al-Shahi Salman","given":"Rustam"},{"family":"M?ller","given":"S?ren"},{"family":"Poulsen","given":"Frantz Rom"},{"family":"Potteg?rd","given":"Anton"},{"family":"Gaist","given":"David"}],"issued":{"date-parts":[["2018"]]}}},{"id":98,"uris":[""],"uri":[""],"itemData":{"id":98,"type":"article-journal","abstract":"We examined the predictive value of the discharge diagnoses of stroke and transient ischemic attack (TIA) in The National Registry of Patients (NRP) for participants in the Danish cohort study \"Diet, Cancer, and Health.\" We retrieved all probable incident registered cases of stroke and TIA, i.e., ICD-10: I60-69.8, or G45 (n = 581) within the cohort from the NRP. Medical records and hospital discharge summaries were retrieved and reviewed using a standardized form. Overall, 299 of 377 cases (79.3%, 95% CI: 74.9-83.3%) of stroke recorded were confirmed. Subarachnoidal hemorrhage and intracerebral hemorrhage were confirmed in 14 of 29 cases (48.3%, 95% CI: 29.4-67.5%), and 23 of 35 cases (65.7%, 95% CI: 47.8-80.9%), respectively. By contrast, ischemic stroke and unspecified stroke were confirmed in 99 of 113 cases (87.6%, 95% CI: 80.1-93.1%) and 152 of 200 cases (76.0%, 95% CI: 69.5-81.7%), respectively. Among 134 patients with a TIA discharge diagnosis, 60.4% (95% CI: 51.6-68.8%) were confirmed. Discharge diagnoses from emergency rooms had lower overall predictive value (48.8%, 95% CI: 39.9-57.8%) than discharge diagnoses from departments of internal medicine (68.8%, 95% CI: 61.3-75.5%) and departments of neurology or neurosurgery (77.9%, 95% CI: 72.3-82.7%). We conclude that stroke and TIA diagnoses in NRP should be used with caution in epidemiological research because the low predictive value for some diagnostic subgroups may lead to serious misclassification and biased results.","container-title":"Journal of Clinical Epidemiology","ISSN":"0895-4356","issue":"6","journalAbbreviation":"J Clin Epidemiol","language":"eng","note":"PMID: 12063102","page":"602-607","source":"PubMed","title":"Predictive value of stroke and transient ischemic attack discharge diagnoses in The Danish National Registry of Patients","volume":"55","author":[{"family":"Johnsen","given":"S?ren P."},{"family":"Overvad","given":"Kim"},{"family":"S?rensen","given":"Henrik Toft"},{"family":"Tj?nneland","given":"Anne"},{"family":"Husted","given":"Steen E."}],"issued":{"date-parts":[["2002",6]]}}},{"id":96,"uris":[""],"uri":[""],"itemData":{"id":96,"type":"article-journal","abstract":"BACKGROUND: Many registers containing routine medical information have been developed for research and surveillance purposes. In epidemiological research assessment of endpoints is often conducted via registers. In the present study we validated stroke and transient ischemic attack (TIA) diagnoses in the Danish National Register of Patients (DNRP).\nMETHODS: Subjects from a Danish cohort study, the Copenhagen City Heart Study (n = 19,698), were crosslinked with the DNRP. The following International Classification of Disease 10th revision codes were used to identify possible strokes and TIAs: I60-I69 and G45. Two independent raters reviewed all cases. Positive predictive values of stroke, TIA and stroke subtypes were estimated by dividing the confirmed cases by the total number of cases located in the DNRP. Interrater reliability was tested using kappa statistics.\nRESULTS: Of 236 possible cerebrovascular events, 1 in 6 stroke diagnoses did not meet study criteria. The majority of events in the DNRP were registered as unspecified stroke (I64), n = 105 (44%), of which two thirds were diagnosed as ischemic stroke events by the raters. Intracerebral hemorrhage and ischemic stroke had a positive predictive value from 74 to 97%, respectively.\nCONCLUSION: Our results show that the DNRP tends to overestimate the number of cerebrovascular events, while ischemic stroke is underestimated.","container-title":"Neuroepidemiology","DOI":"10.1159/000102143","ISSN":"1423-0208","issue":"3","journalAbbreviation":"Neuroepidemiology","language":"eng","note":"PMID: 17478969","page":"150-154","source":"PubMed","title":"Validity of stroke diagnoses in a National Register of Patients","volume":"28","author":[{"family":"Krarup","given":"Lars-Henrik"},{"family":"Boysen","given":"Gudrun"},{"family":"Janjua","given":"Huma"},{"family":"Prescott","given":"Eva"},{"family":"Truelsen","given":"Thomas"}],"issued":{"date-parts":[["2007"]]}}},{"id":611,"uris":[""],"uri":[""],"itemData":{"id":611,"type":"article-journal","abstract":"AIMS: To determine the positive predictive values for stroke discharge diagnoses, including subarachnoidal haemorrhage, intracerebral haemorrhage and cerebral infarction in the Danish National Patient Register.\nMETHODS: Participants in the Danish cohort study Diet, Cancer and Health with a stroke discharge diagnosis in the National Patient Register between 1993 and 2009 were identified and their medical records were retrieved for validation of the diagnoses.\nRESULTS: A total of 3326 records of possible cases of stroke were reviewed. The overall positive predictive value for stroke was 69.3% (95% confidence interval (CI) 67.8-70.9%). The predictive values differed according to hospital characteristics, with the highest predictive value of 87.8% (95% CI 85.5-90.1%) found in departments of neurology and the lowest predictive value of 43.0% (95% CI 37.6-48.5%) found in outpatient clinics.\nCONCLUSIONS: The overall stroke diagnosis in the Danish National Patient Register had a limited predictive value. We therefore recommend the critical use of non-validated register data for research on stroke. The possibility of optimising the predictive values based on more advanced algorithms should be considered.","container-title":"Scandinavian Journal of Public Health","DOI":"10.1177/1403494817716582","ISSN":"1651-1905","issue":"6","journalAbbreviation":"Scand J Public Health","language":"eng","note":"PMID: 28701076","page":"630-636","source":"PubMed","title":"Predictive value of stroke discharge diagnoses in the Danish National Patient Register","volume":"45","author":[{"family":"Lühdorf","given":"Pernille"},{"family":"Overvad","given":"Kim"},{"family":"Schmidt","given":"Erik B."},{"family":"Johnsen","given":"S?ren P."},{"family":"Bach","given":"Flemming W."}],"issued":{"date-parts":[["2017",8]]}}}],"schema":""} 32–34,36 Studies predating year 2000 reported PPVs of 66% ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"dQR4GNUD","properties":{"formattedCitation":"\\super 33\\nosupersub{}","plainCitation":"33","noteIndex":0},"citationItems":[{"id":98,"uris":[""],"uri":[""],"itemData":{"id":98,"type":"article-journal","abstract":"We examined the predictive value of the discharge diagnoses of stroke and transient ischemic attack (TIA) in The National Registry of Patients (NRP) for participants in the Danish cohort study \"Diet, Cancer, and Health.\" We retrieved all probable incident registered cases of stroke and TIA, i.e., ICD-10: I60-69.8, or G45 (n = 581) within the cohort from the NRP. Medical records and hospital discharge summaries were retrieved and reviewed using a standardized form. Overall, 299 of 377 cases (79.3%, 95% CI: 74.9-83.3%) of stroke recorded were confirmed. Subarachnoidal hemorrhage and intracerebral hemorrhage were confirmed in 14 of 29 cases (48.3%, 95% CI: 29.4-67.5%), and 23 of 35 cases (65.7%, 95% CI: 47.8-80.9%), respectively. By contrast, ischemic stroke and unspecified stroke were confirmed in 99 of 113 cases (87.6%, 95% CI: 80.1-93.1%) and 152 of 200 cases (76.0%, 95% CI: 69.5-81.7%), respectively. Among 134 patients with a TIA discharge diagnosis, 60.4% (95% CI: 51.6-68.8%) were confirmed. Discharge diagnoses from emergency rooms had lower overall predictive value (48.8%, 95% CI: 39.9-57.8%) than discharge diagnoses from departments of internal medicine (68.8%, 95% CI: 61.3-75.5%) and departments of neurology or neurosurgery (77.9%, 95% CI: 72.3-82.7%). We conclude that stroke and TIA diagnoses in NRP should be used with caution in epidemiological research because the low predictive value for some diagnostic subgroups may lead to serious misclassification and biased results.","container-title":"Journal of Clinical Epidemiology","ISSN":"0895-4356","issue":"6","journalAbbreviation":"J Clin Epidemiol","language":"eng","note":"PMID: 12063102","page":"602-607","source":"PubMed","title":"Predictive value of stroke and transient ischemic attack discharge diagnoses in The Danish National Registry of Patients","volume":"55","author":[{"family":"Johnsen","given":"S?ren P."},{"family":"Overvad","given":"Kim"},{"family":"S?rensen","given":"Henrik Toft"},{"family":"Tj?nneland","given":"Anne"},{"family":"Husted","given":"Steen E."}],"issued":{"date-parts":[["2002",6]]}}}],"schema":""} 33 and 74% ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"xBlzsLdQ","properties":{"formattedCitation":"\\super 34\\nosupersub{}","plainCitation":"34","noteIndex":0},"citationItems":[{"id":96,"uris":[""],"uri":[""],"itemData":{"id":96,"type":"article-journal","abstract":"BACKGROUND: Many registers containing routine medical information have been developed for research and surveillance purposes. In epidemiological research assessment of endpoints is often conducted via registers. In the present study we validated stroke and transient ischemic attack (TIA) diagnoses in the Danish National Register of Patients (DNRP).\nMETHODS: Subjects from a Danish cohort study, the Copenhagen City Heart Study (n = 19,698), were crosslinked with the DNRP. The following International Classification of Disease 10th revision codes were used to identify possible strokes and TIAs: I60-I69 and G45. Two independent raters reviewed all cases. Positive predictive values of stroke, TIA and stroke subtypes were estimated by dividing the confirmed cases by the total number of cases located in the DNRP. Interrater reliability was tested using kappa statistics.\nRESULTS: Of 236 possible cerebrovascular events, 1 in 6 stroke diagnoses did not meet study criteria. The majority of events in the DNRP were registered as unspecified stroke (I64), n = 105 (44%), of which two thirds were diagnosed as ischemic stroke events by the raters. Intracerebral hemorrhage and ischemic stroke had a positive predictive value from 74 to 97%, respectively.\nCONCLUSION: Our results show that the DNRP tends to overestimate the number of cerebrovascular events, while ischemic stroke is underestimated.","container-title":"Neuroepidemiology","DOI":"10.1159/000102143","ISSN":"1423-0208","issue":"3","journalAbbreviation":"Neuroepidemiology","language":"eng","note":"PMID: 17478969","page":"150-154","source":"PubMed","title":"Validity of stroke diagnoses in a National Register of Patients","volume":"28","author":[{"family":"Krarup","given":"Lars-Henrik"},{"family":"Boysen","given":"Gudrun"},{"family":"Janjua","given":"Huma"},{"family":"Prescott","given":"Eva"},{"family":"Truelsen","given":"Thomas"}],"issued":{"date-parts":[["2007"]]}}}],"schema":""} 34, respectively, while a study ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"SkZ8rOtI","properties":{"formattedCitation":"\\super 36\\nosupersub{}","plainCitation":"36","noteIndex":0},"citationItems":[{"id":611,"uris":[""],"uri":[""],"itemData":{"id":611,"type":"article-journal","abstract":"AIMS: To determine the positive predictive values for stroke discharge diagnoses, including subarachnoidal haemorrhage, intracerebral haemorrhage and cerebral infarction in the Danish National Patient Register.\nMETHODS: Participants in the Danish cohort study Diet, Cancer and Health with a stroke discharge diagnosis in the National Patient Register between 1993 and 2009 were identified and their medical records were retrieved for validation of the diagnoses.\nRESULTS: A total of 3326 records of possible cases of stroke were reviewed. The overall positive predictive value for stroke was 69.3% (95% confidence interval (CI) 67.8-70.9%). The predictive values differed according to hospital characteristics, with the highest predictive value of 87.8% (95% CI 85.5-90.1%) found in departments of neurology and the lowest predictive value of 43.0% (95% CI 37.6-48.5%) found in outpatient clinics.\nCONCLUSIONS: The overall stroke diagnosis in the Danish National Patient Register had a limited predictive value. We therefore recommend the critical use of non-validated register data for research on stroke. The possibility of optimising the predictive values based on more advanced algorithms should be considered.","container-title":"Scandinavian Journal of Public Health","DOI":"10.1177/1403494817716582","ISSN":"1651-1905","issue":"6","journalAbbreviation":"Scand J Public Health","language":"eng","note":"PMID: 28701076","page":"630-636","source":"PubMed","title":"Predictive value of stroke discharge diagnoses in the Danish National Patient Register","volume":"45","author":[{"family":"Lühdorf","given":"Pernille"},{"family":"Overvad","given":"Kim"},{"family":"Schmidt","given":"Erik B."},{"family":"Johnsen","given":"S?ren P."},{"family":"Bach","given":"Flemming W."}],"issued":{"date-parts":[["2017",8]]}}}],"schema":""} 36 concerning data from 1993 to 2009 reported a PPV of 76%. Finally, a study ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"hw8iTXXT","properties":{"formattedCitation":"\\super 32\\nosupersub{}","plainCitation":"32","noteIndex":0},"citationItems":[{"id":939,"uris":[""],"uri":[""],"itemData":{"id":939,"type":"article-journal","abstract":"Purpose: The purpose of this study is to establish the validity of intracerebral hemorrhage (ICH) diagnoses in the Danish Stroke Registry (DSR) and the Danish National Patient Registry (DNPR).\nPatients and methods: We estimated the positive predictive value (PPV) of ICH diagnoses for a sample of 500 patients from the DSR (patients recorded under ICH diagnosis) and DNPR (International Classification of Diseases, version 10, code I61) during 2010-2015, using discharge summaries and brain imaging reports (minimal data). We estimated PPVs for any ICH (a-ICH) and spontaneous ICH (s-ICH) alone. Furthermore, we assessed PPVs according to whether patients were recorded in both or only one of the registries. Finally, in a subsample with ICH diagnoses with access to full medical records and original imaging studies (extensive data, n=100), we compared s-ICH diagnosis and hemorrhage location after use of extensive vs minimal data.\nResults: In the DSR, the PPVs were 94% (95% CI, 91%-96%) for a-ICH and 85% (95% CI, 81%-88%) for s-ICH. In the DNPR, the PPVs were 88% (95% CI, 84%-91%) for a-ICH and 75% (95% CI, 70%-79%) for s-ICH. PPVs for s-ICH for patients recorded in both registries, DSR only, and DNPR only were 86% (95% CI, 82-99), 80% (95%CI, 71-87), and 49% (95%CI, 39-59), respectively. Evaluation of extensive vs minimal data verified s-ICH diagnosis in 98% and hemorrhage location in 94%.\nConclusion: The validity of a-ICH diagnoses in DSR and DNPR is sufficiently high to support their use in epidemiologic studies. For s-ICH, validity was high in DSR. In DNPR, s-ICH validity was lower, markedly so for the small subgroup of patients only recorded in this registry. Minimal data including discharge summaries and brain imaging reports were feasible and valid for identifying ICH location.","container-title":"Clinical Epidemiology","DOI":"10.2147/CLEP.S167576","ISSN":"1179-1349","journalAbbreviation":"Clin Epidemiol","language":"eng","note":"PMID: 30123006\nPMCID: PMC6086098","page":"941-948","source":"PubMed","title":"Intracerebral hemorrhage: positive predictive value of diagnosis codes in two nationwide Danish registries","title-short":"Intracerebral hemorrhage","volume":"10","author":[{"family":"Hald","given":"Stine Munk"},{"family":"Kring Sloth","given":"Christine"},{"family":"Hey","given":"Sabine Morris"},{"family":"Madsen","given":"Charlotte"},{"family":"Nguyen","given":"Nina"},{"family":"García Rodríguez","given":"Luis Alberto"},{"family":"Al-Shahi Salman","given":"Rustam"},{"family":"M?ller","given":"S?ren"},{"family":"Poulsen","given":"Frantz Rom"},{"family":"Potteg?rd","given":"Anton"},{"family":"Gaist","given":"David"}],"issued":{"date-parts":[["2018"]]}}}],"schema":""} 32 by our group with data from the same region as the present study for the years 2010-2015 reported a PPV of 75% for s-ICH in DNPR. The reported PPVs from previous studies by other groups presumably also represent s-ICH, as stroke was defined according to WHO criteria in these studies (although only one study ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"TYXiwwtZ","properties":{"formattedCitation":"\\super 36\\nosupersub{}","plainCitation":"36","noteIndex":0},"citationItems":[{"id":611,"uris":[""],"uri":[""],"itemData":{"id":611,"type":"article-journal","abstract":"AIMS: To determine the positive predictive values for stroke discharge diagnoses, including subarachnoidal haemorrhage, intracerebral haemorrhage and cerebral infarction in the Danish National Patient Register.\nMETHODS: Participants in the Danish cohort study Diet, Cancer and Health with a stroke discharge diagnosis in the National Patient Register between 1993 and 2009 were identified and their medical records were retrieved for validation of the diagnoses.\nRESULTS: A total of 3326 records of possible cases of stroke were reviewed. The overall positive predictive value for stroke was 69.3% (95% confidence interval (CI) 67.8-70.9%). The predictive values differed according to hospital characteristics, with the highest predictive value of 87.8% (95% CI 85.5-90.1%) found in departments of neurology and the lowest predictive value of 43.0% (95% CI 37.6-48.5%) found in outpatient clinics.\nCONCLUSIONS: The overall stroke diagnosis in the Danish National Patient Register had a limited predictive value. We therefore recommend the critical use of non-validated register data for research on stroke. The possibility of optimising the predictive values based on more advanced algorithms should be considered.","container-title":"Scandinavian Journal of Public Health","DOI":"10.1177/1403494817716582","ISSN":"1651-1905","issue":"6","journalAbbreviation":"Scand J Public Health","language":"eng","note":"PMID: 28701076","page":"630-636","source":"PubMed","title":"Predictive value of stroke discharge diagnoses in the Danish National Patient Register","volume":"45","author":[{"family":"Lühdorf","given":"Pernille"},{"family":"Overvad","given":"Kim"},{"family":"Schmidt","given":"Erik B."},{"family":"Johnsen","given":"S?ren P."},{"family":"Bach","given":"Flemming W."}],"issued":{"date-parts":[["2017",8]]}}}],"schema":""} 36 explicitly stated that traumatic ICH was excluded). We conclude that the PPV of 70% in this study, although somewhat lower, is in line with previous reports on the validity of s-ICH in DNPR. We report a PPV of 81% for s-ICH in DSR, which is similar to the result of our previous study (PPV 85%) in the same catchment area. We previously reported higher PPVs for a-ICH in both DNPR (88%) and DSR (94%), compared with the results of the present study (DNPR: 76%; DSR: 87%). In our previous study, we only studied a sample of patients with ICH diagnoses and only validated patients with available EMR records. This may have resulted in overrepresentation of patients treated at the university hospital in the catchment area, as this hospital had the largest patient volume and in addition, was the first hospital in RSD to switch to the EMR system. We also note that our estimates of a-ICH in the present study would have been even higher, had we included certain cases of ICH that were excluded by design (eg, ICH due to trauma, hemorrhagic transformation, iatrogenic ICH). We report novel data on the sensitivity of ICH diagnoses in DSR and DNPR. As DSR is primarily based on reporting from stroke units in Denmark, patients only admitted to non-stroke units could potentially be missed. Our results regarding sensitivity of DSR for s-ICH (79%) were therefore reassuring, although we did observe some variation in sensitivity over time and across age-groups. While the cause of this variation is unknown to us, these findings emphasize the need for periodic validation of the data. DNPR inpatient data with primary diagnostic position codes are frequently used in Danish studies of cerebrovascular disorders, as this approach is believed to result in outcomes with higher validity than data with broader criteria (eg, inclusion of inpatients regardless of diagnostic position of code). ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"tcpcHXU9","properties":{"formattedCitation":"\\super 4,6,46\\uc0\\u8211{}50\\nosupersub{}","plainCitation":"4,6,46–50","noteIndex":0},"citationItems":[{"id":47,"uris":[""],"uri":[""],"itemData":{"id":47,"type":"article-journal","DOI":"10.1001/jama.2017.0639","journalAbbreviation":"JAMA","page":"836-846","title":"Association of antithrombotic drug use with subdural hematoma risk","volume":"317","author":[{"family":"Gaist","given":"D."},{"family":"García Rodríguez","given":"LA"},{"family":"Hellfritzsch","given":"M"},{"family":"Poulsen","given":"FR"},{"family":"Halle","given":"B"},{"family":"Hallas","given":"J."},{"family":"Potteg?rd","given":"A"}],"issued":{"date-parts":[["2017"]]}}},{"id":104,"uris":[""],"uri":[""],"itemData":{"id":104,"type":"article-journal","abstract":"OBJECTIVE: To estimate the risk of occurrence of subarachnoid haemorrhage in first degree relatives (parents, siblings, children) of patients with subarachnoid haemorrhage.\nDESIGN: Population based cohort study using data from the Danish National Discharge Registry and the Central Person Registry.\nSUBJECTS: Incident cases of subarachnoid haemorrhage admitted to hospital from 1977 to 1995 (9367 patients) and their first degree relatives (14 781).\nMAIN OUTCOME MEASURES: The incidence rate of subarachnoid haemorrhage was determined for the relatives and compared with that of the entire population, standardised for age, sex, and calendar period. This process was repeated for patients discharged from neurosurgery units, as diagnoses from these wards had high validity (93%).\nRESULTS: 18 patients had a total of 19 first degree relatives with subarachnoid haemorrhage during the study period, corresponding to a standardised incidence ratio of 2.9 (95% confidence interval 1.9 to 4.6). Patients discharged from neurosurgery wards had a higher standardised incidence ratio (4.5, 2.7 to 7.3).\nCONCLUSIONS: First degree relatives of patients with subarachnoid haemorrhage have a threefold to fivefold increased risk of subarachnoid haemorrhage compared with the general population.","container-title":"BMJ (Clinical research ed.)","ISSN":"0959-8138","issue":"7228","journalAbbreviation":"BMJ","language":"eng","note":"PMID: 10634731\nPMCID: PMC27258","page":"141-145","source":"PubMed","title":"Risk of subarachnoid haemorrhage in first degree relatives of patients with subarachnoid haemorrhage: follow up study based on national registries in Denmark","title-short":"Risk of subarachnoid haemorrhage in first degree relatives of patients with subarachnoid haemorrhage","volume":"320","author":[{"family":"Gaist","given":"D."},{"family":"Vaeth","given":"M."},{"family":"Tsiropoulos","given":"I."},{"family":"Christensen","given":"K."},{"family":"Corder","given":"E."},{"family":"Olsen","given":"J."},{"family":"S?rensen","given":"H. T."}],"issued":{"date-parts":[["2000",1,15]]}}},{"id":1217,"uris":[""],"uri":[""],"itemData":{"id":1217,"type":"article-journal","abstract":"BACKGROUND AND PURPOSE: Stroke is a risk factor for dementia, but the risk of dementia after different stroke types is poorly understood. We examined the long-term risk of dementia among survivors of any first-time stroke and of first-time ischemic stroke, intracerebral hemorrhage, and subarachnoid hemorrhage.\nMETHODS: We conducted a 30-year nationwide population-based cohort study using data from Danish medical databases (1982-2013) covering all Danish hospitals. We identified 84?220 ischemic stroke survivors, 16?723 intracerebral hemorrhage survivors, 9872 subarachnoid hemorrhage survivors, and 104?303 survivors of unspecified stroke types. Patients were aged ≥18 years and survived for at least 3 months after diagnosis. We formed a comparison cohort from the general population (1?075?588 patients without stroke, matched to stroke patients by age and sex). We computed absolute risks and hazard ratios of dementia up to 30 years after stroke.\nRESULTS: The 30-year absolute risk of dementia among stroke survivors was 11.5% (95% confidence interval, 11.2%-11.7%). Compared with the general population, the hazard ratio (95% confidence interval) for dementia among stroke survivors was 1.80 (1.77-1.84) after any stroke, 1.72 (1.66-1.77) after ischemic stroke, 2.70 (2.53-2.89) after intracerebral hemorrhage, and 2.74 (2.45-3.06) after subarachnoid hemorrhage. Younger patients regardless of stroke type faced higher risks of poststroke dementia than older patients. The pattern of hazard ratios by stroke type did not change during follow-up and was not altered appreciably by age, sex, or preexisting diagnoses of vascular conditions.\nCONCLUSIONS: Stroke increases dementia risk. Survivors of intracerebral hemorrhage and subarachnoid hemorrhage are at particularly high long-term risk of poststroke dementia.","container-title":"Stroke","DOI":"10.1161/STROKEAHA.116.015242","ISSN":"1524-4628","issue":"1","journalAbbreviation":"Stroke","language":"eng","note":"PMID: 27899749\nPMCID: PMC5796652","page":"180-186","source":"PubMed","title":"Long-Term Risk of Dementia Among Survivors of Ischemic or Hemorrhagic Stroke","volume":"48","author":[{"family":"Corraini","given":"Priscila"},{"family":"Henderson","given":"Victor W."},{"family":"Ording","given":"Anne G."},{"family":"Pedersen","given":"Lars"},{"family":"Horváth-Puhó","given":"Erzsébet"},{"family":"S?rensen","given":"Henrik T."}],"issued":{"date-parts":[["2017"]]}}},{"id":216,"uris":[""],"uri":[""],"itemData":{"id":216,"type":"article-journal","abstract":"The study objective was to investigate the relationship between use of antithrombotic drugs and subarachnoid haemorrhage (SAH). We identified patients discharged from Danish neurosurgery units with a first-ever SAH diagnosis in 2000 to 2012 (n=5,834). For each case, we selected 40 age-, sex- and period-matched population controls. Conditional logistic regression models were used to estimate odds ratios (aOR), adjusted for comorbidity, education level, and income. Low-dose aspirin (ASA) use for <?1 month was associated with an increased risk of SAH (aOR 1.75, 95?% confidence interval [CI] 1.28-2.40). This aOR decreased to 1.26 (95?%CI: 0.98-1.63) with 2-3 months of ASA use, and approached unity with use for more than three months (1.11, 95?%CI 0.97-1.27). Analyses with first-time users confirmed this pattern, which was also observed for clopidogrel. ASA treatment for three or more years was associated with an aOR of SAH of 1.13 (95?%CI: 0.86-1.49). Short-term use (<?1 month) of vitamin K-antagonists (VKA) yielded an aOR of 1.85 (95?%CI 0.97-3.51) which dropped after 3+ years to 1.24, 95?%CI: 0.86-1.77. The risk of SAH was higher in subjects in dual antithrombotic treatment (aOR 2.08, 95?%CI: 1.26-3.44), and in triple antithrombotic treatment (aOR 5.74, 95?%CI: 1.76-18.77). In conclusion, use of aspirin,clopidogrel and VKA were only associated with an increased risk of SAH in the first three months after starting treatment. Long-term aspirin use carried no reduced SAH risk. Results should be interpreted cautiously due to their observational nature.","container-title":"Thrombosis and Haemostasis","DOI":"10.1160/TH15-04-0316","ISSN":"0340-6245","issue":"5","journalAbbreviation":"Thromb. Haemost.","language":"eng","note":"PMID: 26202836","page":"1064-1075","source":"PubMed","title":"Antithrombotic drugs and subarachnoid haemorrhage risk. A nationwide case-control study in Denmark","volume":"114","author":[{"family":"Potteg?rd","given":"Anton"},{"family":"García Rodríguez","given":"Luis Alberto"},{"family":"Poulsen","given":"Frantz Rom"},{"family":"Hallas","given":"Jesper"},{"family":"Gaist","given":"David"}],"issued":{"date-parts":[["2015",11]]}}},{"id":1223,"uris":[""],"uri":[""],"itemData":{"id":1223,"type":"article-journal","abstract":"BACKGROUND: The aim of the study was to investigate the associated risk of stroke after discharge of infective endocarditis (IE) in patients with stroke during IE admission compared with patients without stroke during IE admission.\nMETHODS: Using Danish nationwide registries, we identified nonsurgically treated patients with IE discharged alive in the period from 1996 to 2016. The study population was grouped into (1) patients with stroke during IE admission and (2) patients without stroke during IE admission. Multivariable adjusted Cox proportional-hazard analysis was used to compare the associated risk of stroke between groups.\nRESULTS: We identified 4,284 patients with IE, of whom 239 (5.6%) had a stroke during IE admission. We identified differentials in the associated risk of stroke during follow-up between groups (P = .006 for interaction with time). The associated risk of stroke was higher in patients with stroke during IE admission with a 1-year follow-up, HR = 3.21 (95% CI 1.66-6.20), compared with patients without stroke during IE admission. From 1 to 5 years of follow-up, we identified no difference in the associated risk of stroke between groups, HR = 0.91 (95% CI 0.33-2.50).\nCONCLUSIONS: Patients with nonsurgically treated IE with a stroke during IE admission were at significant higher associated risk of subsequent stroke within the first year of follow-up as compared with patients without a stroke during IE admission. This risk difference was not evident beyond 1 year of discharge. These findings underline the need for identification of causes and mechanisms of recurrent strokes after IE to develop preventive means.","container-title":"American Heart Journal","DOI":"10.1016/j.ahj.2019.03.010","ISSN":"1097-6744","journalAbbreviation":"Am. Heart J.","language":"eng","note":"PMID: 31004917","page":"144-151","source":"PubMed","title":"Risk of stroke subsequent to infective endocarditis: A nationwide study","title-short":"Risk of stroke subsequent to infective endocarditis","volume":"212","author":[{"family":"?stergaard","given":"Lauge"},{"family":"Andersson","given":"Niklas Worm"},{"family":"Kristensen","given":"S?ren Lund"},{"family":"Dahl","given":"Anders"},{"family":"Bundgaard","given":"Henning"},{"family":"Iversen","given":"Kasper"},{"family":"Eske-Bruun","given":"Niels"},{"family":"Gislason","given":"Gunnar"},{"family":"Torp-Pedersen","given":"Christian"},{"family":"Valeur","given":"Nana"},{"family":"K?ber","given":"Lars"},{"family":"Fosb?l","given":"Emil Loldrup"}],"issued":{"date-parts":[["2019"]]}}},{"id":1220,"uris":[""],"uri":[""],"itemData":{"id":1220,"type":"article-journal","abstract":"Background Congenital heart disease (CHD) is associated with risk factors for ischemic stroke including cardiac arrhythmias and heart failure. However, few long-term follow-up data exist on ischemic stroke risk and associated mortality in adults with CHD. Methods and Results Using Danish nationwide registries, we identified individuals aged ≥18?years diagnosed with CHD, at any age, from 1963 to 2017 and a sex and birth year-matched (1:10) general population comparison cohort. We computed risks, as well as sex and birth year-adjusted hazard ratios (aHRs) for ischemic stroke and 30-day post-stroke mortality in CHD adults compared with the general population. Analyses were stratified according to age <60?years (young) and ≥60 years (older). We identified 16?836 adults with CHD. The risk of ischemic stroke at age 60?years was 7.4% in the CHD cohort and 2.9% in the general population cohort. The adjusted hazard ratios for ischemic stroke compared with the general population was 3.8 (95% CI: 3.3-4.3) in young CHD adults and 1.6 (95% CI: 1.4-1.9) in older CHD adults. The adjusted hazard ratios for post-stroke mortality compared with the general population was 2.3 (95% CI: 1.2-4.4) in young CHD adults and 1.3 (95% CI: 0.9-1.9) in older CHD adults. Conclusions Both younger and older CHD adults have an increased risk of ischemic stroke and by 60?years of age 7.4% of CHD adults will have had an ischemic stroke. Post-stroke mortality was also increased in CHD adults compared with the general population.","container-title":"Journal of the American Heart Association","DOI":"10.1161/JAHA.118.011870","ISSN":"2047-9980","issue":"15","journalAbbreviation":"J Am Heart Assoc","language":"eng","note":"PMID: 31315496\nPMCID: PMC6761631","page":"e011870","source":"PubMed","title":"Ischemic Stroke in Adults With Congenital Heart Disease: A Population-Based Cohort Study","title-short":"Ischemic Stroke in Adults With Congenital Heart Disease","volume":"8","author":[{"family":"Pedersen","given":"Mette Glavind Bülow"},{"family":"Olsen","given":"Morten S."},{"family":"Schmidt","given":"Morten"},{"family":"Johnsen","given":"S?ren P."},{"family":"Learn","given":"Christopher"},{"family":"Laursen","given":"Henning B."},{"family":"Madsen","given":"Nicolas L."}],"issued":{"date-parts":[["2019"]],"season":"06"}}},{"id":1172,"uris":[""],"uri":[""],"itemData":{"id":1172,"type":"article-journal","abstract":"BACKGROUND: Selective serotonin reuptake inhibitors (SSRIs) use may be associated with development of subdural hematoma (SDH).\nOBJECTIVES: To estimate SDH risk associated with antidepressant use, including when combined with antithrombotics, or nonsteroidal anti-inflammatory drugs (NSAIDs).\nPATIENTS/METHODS: We performed this case-control study based on Danish registries. We included 10?885 incident cases of SDH and 435?379 matched general population controls. We calculated odds ratios (95% confidence interval) adjusted for comorbidity, co-medication, education level, and income (aOR).\nRESULTS: We found that current use of SSRIs (aOR1.32 [1.25-1.38]) and non-SSRIs (aOR 1.19 [1.13-1.26]) was associated with a higher SDH risk, compared with non-use of antidepressants. Risks were higher with short duration of current use (eg, <1?month of current use: aOR 2.55 [2.07-3.15] for SSRI, 1.88 [1.46-2.41] for non-SSRIs; >3?years of current use: 1.04 [0.93-1.17] for SSRI and 1.12 [0.98-1.28] for non-SSRIs). Combined use of antidepressants with either antithrombotics or NSAIDs yielded similar ORs to those observed for single use of antithrombotics or NSAIDs. Stronger associations were observed for antidepressants combined with both vitamin K antagonists (VKAs) and NSAIDs (SSRI, VKA, & NSAID: aOR 5.51 [2.70-11-22]; non-SSRI, VKA, & NSAID: 6.81 [2.37-19-60]).\nCONCLUSIONS: Antidepressant use was associated with higher risk of SDH that seemed largely restricted to first year of treatment. In absolute terms this risk is judged to be small, given the low SDH incidence rate. With one possible exception (triple use of antidepressants, NSAIDs, and VKAs), risk estimates of SDH for combined regimens of antidepressants with antithrombotics or NSAIDs provided little evidence of interactions.","container-title":"Journal of thrombosis and haemostasis: JTH","DOI":"10.1111/jth.14658","ISSN":"1538-7836","issue":"2","journalAbbreviation":"J. Thromb. Haemost.","language":"eng","note":"PMID: 31609047","page":"318-327","source":"PubMed","title":"Antidepressant drug use and subdural hematoma risk","volume":"18","author":[{"family":"Gaist","given":"David"},{"family":"García Rodríguez","given":"Luis Alberto"},{"family":"Hald","given":"Stine Munk"},{"family":"Hellfritzsch","given":"Maja"},{"family":"Poulsen","given":"Frantz R."},{"family":"Halle","given":"Bo"},{"family":"Hallas","given":"Jesper"},{"family":"Potteg?rd","given":"Anton"}],"issued":{"date-parts":[["2020",2]]}}}],"schema":""} 4,6,46–50 Our findings support this strategy with regard to s-ICH. We also note that the high sensitivity of s-ICH based on inpatient primary diagnostic position codes was stable in the 9-year study period and across age-groups. The distribution of location of hemorrhage in patients with s-ICH was as expected from the literature. ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"KPXBHcsb","properties":{"formattedCitation":"\\super 37,51,52\\nosupersub{}","plainCitation":"37,51,52","noteIndex":0},"citationItems":[{"id":651,"uris":[""],"uri":[""],"itemData":{"id":651,"type":"article-journal","abstract":"BACKGROUND AND PURPOSE: The characteristics of intracerebral hemorrhage (ICH) may vary by ICH location because of differences in the distribution of underlying cerebral small vessel diseases. Therefore, we investigated the incidence, characteristics, and outcome of lobar and nonlobar ICH.\nMETHODS: In a population-based, prospective inception cohort study of ICH, we used multiple overlapping sources of case ascertainment and follow-up to identify and validate ICH diagnoses in 2010 to 2011 in an adult population of 695 335.\nRESULTS: There were 128 participants with first-ever primary ICH. The overall incidence of lobar ICH was similar to nonlobar ICH (9.8 [95% confidence interval, 7.7-12.4] versus 8.6 [95% confidence interval, 6.7-11.1] per 100 000 adults/y). At baseline, adults with lobar ICH were more likely to have preceding dementia (21% versus 5%; P=0.01), lower Glasgow Coma Scale scores (median, 13 versus 14; P=0.03), larger ICHs (median, 38 versus 11 mL; P<0.001), subarachnoid extension (57% versus 5%; P<0.001), and subdural extension (15% versus 3%; P=0.02) than those with nonlobar ICH. One-year case fatality was lower after lobar ICH than after nonlobar ICH (adjusted odds ratio for death at 1 year: lobar versus nonlobar ICH 0.21; 95% confidence interval, 0.07-0.63; P=0.006, after adjustment for known predictors of outcome). There were 4 recurrent ICHs, which occurred exclusively in survivors of lobar ICH (annual risk of recurrent ICH after lobar ICH, 11.8%; 95% confidence interval, 4.6%-28.5% versus 0% after nonlobar ICH; log-rank P=0.04).\nCONCLUSIONS: The baseline characteristics and outcome of lobar ICH differ from other locations.","container-title":"Stroke","DOI":"10.1161/STROKEAHA.114.007953","ISSN":"1524-4628","issue":"2","journalAbbreviation":"Stroke","language":"eng","note":"PMID: 25586833","page":"361-368","source":"PubMed","title":"Influence of intracerebral hemorrhage location on incidence, characteristics, and outcome: population-based study","title-short":"Influence of intracerebral hemorrhage location on incidence, characteristics, and outcome","volume":"46","author":[{"family":"Samarasekera","given":"Neshika"},{"family":"Fonville","given":"Arthur"},{"family":"Lerpiniere","given":"Christine"},{"family":"Farrall","given":"Andrew J."},{"family":"Wardlaw","given":"Joanna M."},{"family":"White","given":"Philip M."},{"family":"Smith","given":"Colin"},{"family":"Al-Shahi Salman","given":"Rustam"},{"literal":"Lothian Audit of the Treatment of Cerebral Haemorrhage Collaborators"}],"issued":{"date-parts":[["2015",2]]}}},{"id":749,"uris":[""],"uri":[""],"itemData":{"id":749,"type":"article-journal","abstract":"A better understanding of the natural history of intracerebral haemorrhages (ICH) with cohorts representing the whole spectrum of the disease is necessary to improve treatment. Our aim was to identify potential differences in baseline characteristics and short-term outcomes of patients with non-traumatic ICH, included in a hospital- and in a population-based stroke registry. We compared 373 patients recruited in a university hospital and the last 373 ICH patients included in a population-based registry. Both cohorts included consecutive patients with non-traumatic parenchymal haemorrhages. In the hospital cohort, we collected data from all patients admitted in the emergency room, irrespective of the clinical severity and of the specialist in charge of the patient.In the hospital cohort, patients were younger and more often alcoholic, but these differences may be explained by the younger age and a higher prevalence of alcoholism in this area. Patients also had more frequently hypercholesterolemia, and were more often under antiplatelet therapy. Both cohorts did not differ for intra-hospital casefatality rate.The characteristics of patients included in the hospital cohort were very close to those of patients from a population-based registry, and the differences observed are likely to be explained by differences in the characteristics of the populations in the two areas and different periods of recruitment. Recruiting patients in emergency rooms, and not in stroke units, neurological, or neurosurgical departments, has enabled us to build a cohort of ICH patients representative of the whole spectrum of the disease, with minimised recruitment bias and maximised precision of the variables collected. This cohort may, therefore, provide reliable information on the natural history of ICH.","container-title":"Journal of Neurology","DOI":"10.1007/s00415-009-0030-3","ISSN":"1432-1459","issue":"2","journalAbbreviation":"J. Neurol.","language":"eng","note":"PMID: 19271106","page":"198-202","source":"PubMed","title":"Intra-cerebral haemorrhages: are there any differences in baseline characteristics and intra-hospital mortality between hospitaland population-based registries?","title-short":"Intra-cerebral haemorrhages","volume":"256","author":[{"family":"Cordonnier","given":"Charlotte"},{"family":"Rutgers","given":"Matthieu P."},{"family":"Dumont","given":"Frédéric"},{"family":"Pasquini","given":"Marta"},{"family":"Lejeune","given":"Jean-Paul"},{"family":"Garrigue","given":"Delphine"},{"family":"Béjot","given":"Yannick"},{"family":"Leclerc","given":"Xavier"},{"family":"Giroud","given":"Maurice"},{"family":"Leys","given":"Didier"},{"family":"Hénon","given":"Hilde"}],"issued":{"date-parts":[["2009",2]]}}},{"id":747,"uris":[""],"uri":[""],"itemData":{"id":747,"type":"article-journal","abstract":"BACKGROUND: The incidence of intracerebral haemorrhage (ICH) in Hispanics is high, especially of non-lobar ICH. Our aim was to ascertain prospectively the incidence of first-ever spontaneous ICH (SICH) stratified by localisation in a Hispanic-Mestizo population of the north of Chile.\nMETHODS: Between July 2000 and June 2002 all possible cases of ICH were ascertained from multiple overlapping sources. The cases were allocated according to localisation. Those with vascular malformations or non-identifiable localisations were excluded.\nRESULTS: We identified a total of 69 cases of first-ever ICH. Of these, 64 (92.7%) had SICH, of which we allocated 58 cases (84%) to non-lobar or lobar localisation. The mean age was 57.3 +/- 17 years, and 62.3% of the subjects were male. The age-adjusted incidence rates were 13.8 (non-lobar) and 4.9 (lobar) per 100,000 person-years. Non-lobar SICH was more frequent in young males and lobar SICH in older women. The non-lobar-to-lobar ratio was similar to previous findings in Hispanics. Hypertension was more frequent in non-lobar SICH and in diabetes, heavy drinking and antithrombotic use in lobar SICH, but in none significantly. There was no association between localisation and prognosis.\nCONCLUSIONS: The incidence of non-lobar SICH was high, but lower than in most non-white populations. This lower incidence could be due to a lower population prevalence of risk factors, a higher socioeconomic level in this population, or chance.","container-title":"Neuroepidemiology","DOI":"10.1159/000289353","ISSN":"1423-0208","issue":"4","journalAbbreviation":"Neuroepidemiology","language":"eng","note":"PMID: 20197705","page":"214-221","source":"PubMed","title":"Incidence of lobar and non-lobar spontaneous intracerebral haemorrhage in a predominantly Hispanic-Mestizo population--the PISCIS stroke project: a community-based prospective study in Iquique, Chile","title-short":"Incidence of lobar and non-lobar spontaneous intracerebral haemorrhage in a predominantly Hispanic-Mestizo population--the PISCIS stroke project","volume":"34","author":[{"family":"Lavados","given":"Pablo M."},{"family":"Sacks","given":"Claudio"},{"family":"Prina","given":"Liliana"},{"family":"Escobar","given":"Arturo"},{"family":"Tossi","given":"Claudia"},{"family":"Araya","given":"Fernando"},{"family":"Feuerhake","given":"Walter"},{"family":"Gálvez","given":"Marcelo"},{"family":"Salinas","given":"Rodrigo"},{"family":"Alvarez","given":"Gonzalo"}],"issued":{"date-parts":[["2010"]]}}}],"schema":""} 37,51,52 However, we did not provide results regarding mixed-location ICH (ie, lobar and deep), as we excluded patients with a history of ICH; also, among the included patients we only had information on concurrent multiple ICHs at our disposal. When assessing for mixed-location ICH, a more appropriate method would have been to evaluate patients with sufficiently sensitive brain imaging studies (eg, MRI with SWI or T2* sequences) for signs of previous hemorrhage,. ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"LTVDrDGU","properties":{"formattedCitation":"\\super 53\\nosupersub{}","plainCitation":"53","noteIndex":0},"citationItems":[{"id":1174,"uris":[""],"uri":[""],"itemData":{"id":1174,"type":"article-journal","abstract":"OBJECTIVE: To assess the predominant type of cerebral small vessel disease (SVD) and recurrence risk in patients who present with a combination of lobar and deep intracerebral hemorrhage (ICH)/microbleed locations (mixed ICH).\nMETHODS: Of 391 consecutive patients with primary ICH enrolled in a prospective registry, 75 (19%) had mixed ICH. Their demographics, clinical/laboratory features, and SVD neuroimaging markers were compared to those of 191 patients with probable cerebral amyloid angiopathy (CAA-ICH) and 125 with hypertensive strictly deep microbleeds and ICH (HTN-ICH). ICH recurrence and case fatality were also analyzed.\nRESULTS: Patients with mixed ICH showed a higher burden of vascular risk factors reflected by a higher rate of left ventricular hypertrophy, higher creatinine values, and more lacunes and severe basal ganglia (BG) enlarged perivascular spaces (EPVS) than patients with CAA-ICH (all p < 0.05). In multivariable models mixed ICH diagnosis was associated with higher creatinine levels (odds ratio [OR] 2.5, 95% confidence interval [CI] 1.2-5.0, p = 0.010), more lacunes (OR 3.4, 95% CI 1.7-6.8), and more severe BG EPVS (OR 5.8, 95% CI 1.7-19.7) than patients with CAA-ICH. Conversely, when patients with mixed ICH were compared to patients with HTN-ICH, they were independently associated with older age (OR 1.03, 95% CI 1.02-1.1), more lacunes (OR 2.4, 95% CI 1.1-5.3), and higher microbleed count (OR 1.6, 95% CI 1.3-2.0). Among 90-day survivors, adjusted case fatality rates were similar for all 3 categories. Annual risk of ICH recurrence was 5.1% for mixed ICH, higher than for HTN-ICH but lower than for CAA-ICH (1.6% and 10.4%, respectively).\nCONCLUSIONS: Mixed ICH, commonly seen on MRI obtained during etiologic workup, appears to be driven mostly by vascular risk factors similar to HTN-ICH but demonstrates more severe parenchymal damage and higher ICH recurrence risk.","container-title":"Neurology","DOI":"10.1212/WNL.0000000000004797","ISSN":"1526-632X","issue":"2","journalAbbreviation":"Neurology","language":"eng","note":"PMID: 29247070\nPMCID: PMC5772153","page":"e119-e126","source":"PubMed","title":"Mixed-location cerebral hemorrhage/microbleeds: Underlying microangiopathy and recurrence risk","title-short":"Mixed-location cerebral hemorrhage/microbleeds","volume":"90","author":[{"family":"Pasi","given":"Marco"},{"family":"Charidimou","given":"Andreas"},{"family":"Boulouis","given":"Gregoire"},{"family":"Auriel","given":"Eitan"},{"family":"Ayres","given":"Alison"},{"family":"Schwab","given":"Kristin M."},{"family":"Goldstein","given":"Joshua N."},{"family":"Rosand","given":"Jonathan"},{"family":"Viswanathan","given":"Anand"},{"family":"Pantoni","given":"Leonardo"},{"family":"Greenberg","given":"Steven M."},{"family":"Gurol","given":"M. Edip"}],"issued":{"date-parts":[["2018"]],"season":"09"}}}],"schema":""} 53 However, in our study, such an approach would probably provide a low yield, as MRI with SWI/T2*, although available upon request at all hospitals throughout the study period, only became part of the routine ICH work-up late in the study period (after 2015) and only in some of the hospitals in RSD (Nina Nguyen, consultant radiologist, personal communication). Our study has some strengths. We used nationwide registries where simple and accurate cross-linkage was facilitated by the unique and permanent civil registration number of residents of Denmark. The majority of previous studies (Table S1) were based on relatively small samples of patients with ICH occurring among participants in various cohort studies conducted in urban areas of Denmark. ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"VVC4CVxV","properties":{"formattedCitation":"\\super 33,34,36\\nosupersub{}","plainCitation":"33,34,36","noteIndex":0},"citationItems":[{"id":98,"uris":[""],"uri":[""],"itemData":{"id":98,"type":"article-journal","abstract":"We examined the predictive value of the discharge diagnoses of stroke and transient ischemic attack (TIA) in The National Registry of Patients (NRP) for participants in the Danish cohort study \"Diet, Cancer, and Health.\" We retrieved all probable incident registered cases of stroke and TIA, i.e., ICD-10: I60-69.8, or G45 (n = 581) within the cohort from the NRP. Medical records and hospital discharge summaries were retrieved and reviewed using a standardized form. Overall, 299 of 377 cases (79.3%, 95% CI: 74.9-83.3%) of stroke recorded were confirmed. Subarachnoidal hemorrhage and intracerebral hemorrhage were confirmed in 14 of 29 cases (48.3%, 95% CI: 29.4-67.5%), and 23 of 35 cases (65.7%, 95% CI: 47.8-80.9%), respectively. By contrast, ischemic stroke and unspecified stroke were confirmed in 99 of 113 cases (87.6%, 95% CI: 80.1-93.1%) and 152 of 200 cases (76.0%, 95% CI: 69.5-81.7%), respectively. Among 134 patients with a TIA discharge diagnosis, 60.4% (95% CI: 51.6-68.8%) were confirmed. Discharge diagnoses from emergency rooms had lower overall predictive value (48.8%, 95% CI: 39.9-57.8%) than discharge diagnoses from departments of internal medicine (68.8%, 95% CI: 61.3-75.5%) and departments of neurology or neurosurgery (77.9%, 95% CI: 72.3-82.7%). We conclude that stroke and TIA diagnoses in NRP should be used with caution in epidemiological research because the low predictive value for some diagnostic subgroups may lead to serious misclassification and biased results.","container-title":"Journal of Clinical Epidemiology","ISSN":"0895-4356","issue":"6","journalAbbreviation":"J Clin Epidemiol","language":"eng","note":"PMID: 12063102","page":"602-607","source":"PubMed","title":"Predictive value of stroke and transient ischemic attack discharge diagnoses in The Danish National Registry of Patients","volume":"55","author":[{"family":"Johnsen","given":"S?ren P."},{"family":"Overvad","given":"Kim"},{"family":"S?rensen","given":"Henrik Toft"},{"family":"Tj?nneland","given":"Anne"},{"family":"Husted","given":"Steen E."}],"issued":{"date-parts":[["2002",6]]}}},{"id":96,"uris":[""],"uri":[""],"itemData":{"id":96,"type":"article-journal","abstract":"BACKGROUND: Many registers containing routine medical information have been developed for research and surveillance purposes. In epidemiological research assessment of endpoints is often conducted via registers. In the present study we validated stroke and transient ischemic attack (TIA) diagnoses in the Danish National Register of Patients (DNRP).\nMETHODS: Subjects from a Danish cohort study, the Copenhagen City Heart Study (n = 19,698), were crosslinked with the DNRP. The following International Classification of Disease 10th revision codes were used to identify possible strokes and TIAs: I60-I69 and G45. Two independent raters reviewed all cases. Positive predictive values of stroke, TIA and stroke subtypes were estimated by dividing the confirmed cases by the total number of cases located in the DNRP. Interrater reliability was tested using kappa statistics.\nRESULTS: Of 236 possible cerebrovascular events, 1 in 6 stroke diagnoses did not meet study criteria. The majority of events in the DNRP were registered as unspecified stroke (I64), n = 105 (44%), of which two thirds were diagnosed as ischemic stroke events by the raters. Intracerebral hemorrhage and ischemic stroke had a positive predictive value from 74 to 97%, respectively.\nCONCLUSION: Our results show that the DNRP tends to overestimate the number of cerebrovascular events, while ischemic stroke is underestimated.","container-title":"Neuroepidemiology","DOI":"10.1159/000102143","ISSN":"1423-0208","issue":"3","journalAbbreviation":"Neuroepidemiology","language":"eng","note":"PMID: 17478969","page":"150-154","source":"PubMed","title":"Validity of stroke diagnoses in a National Register of Patients","volume":"28","author":[{"family":"Krarup","given":"Lars-Henrik"},{"family":"Boysen","given":"Gudrun"},{"family":"Janjua","given":"Huma"},{"family":"Prescott","given":"Eva"},{"family":"Truelsen","given":"Thomas"}],"issued":{"date-parts":[["2007"]]}}},{"id":611,"uris":[""],"uri":[""],"itemData":{"id":611,"type":"article-journal","abstract":"AIMS: To determine the positive predictive values for stroke discharge diagnoses, including subarachnoidal haemorrhage, intracerebral haemorrhage and cerebral infarction in the Danish National Patient Register.\nMETHODS: Participants in the Danish cohort study Diet, Cancer and Health with a stroke discharge diagnosis in the National Patient Register between 1993 and 2009 were identified and their medical records were retrieved for validation of the diagnoses.\nRESULTS: A total of 3326 records of possible cases of stroke were reviewed. The overall positive predictive value for stroke was 69.3% (95% confidence interval (CI) 67.8-70.9%). The predictive values differed according to hospital characteristics, with the highest predictive value of 87.8% (95% CI 85.5-90.1%) found in departments of neurology and the lowest predictive value of 43.0% (95% CI 37.6-48.5%) found in outpatient clinics.\nCONCLUSIONS: The overall stroke diagnosis in the Danish National Patient Register had a limited predictive value. We therefore recommend the critical use of non-validated register data for research on stroke. The possibility of optimising the predictive values based on more advanced algorithms should be considered.","container-title":"Scandinavian Journal of Public Health","DOI":"10.1177/1403494817716582","ISSN":"1651-1905","issue":"6","journalAbbreviation":"Scand J Public Health","language":"eng","note":"PMID: 28701076","page":"630-636","source":"PubMed","title":"Predictive value of stroke discharge diagnoses in the Danish National Patient Register","volume":"45","author":[{"family":"Lühdorf","given":"Pernille"},{"family":"Overvad","given":"Kim"},{"family":"Schmidt","given":"Erik B."},{"family":"Johnsen","given":"S?ren P."},{"family":"Bach","given":"Flemming W."}],"issued":{"date-parts":[["2017",8]]}}}],"schema":""} 33,34,36 In two of these studies,33,66 patients diagnosed with stroke were on average younger than seen in recent population-based studies of stoke. In this study, we included all patients with ICH diagnosis codes seen at any hospital department according to two sources (DSR and DNPR) and regardless of type of hospital contact (inpatient, outpatient or ED), or diagnostic code position in DNPR. By securing data for these potential cases of ICH in an entire region for a 9-year period we ensured a large sample diagnosed through standards corresponding to current clinical practice and in all probability representative of the whole spectrum of this frequently devastating disorder.Therefore, the results of this study are likely better with regard to generalizability as compared with previous studies. Studies based on Danish registries are frequently published in international peer-reviewed journals and therefore presumably have a large impact on research all over the world. The information provided by this manuscript can contribute to the correct interpretation of such register-based studies concerning ICH.Our study has a number of limitations. First, we used discharge letters and brain scan reports to verify the diagnoses, a previously validated method. ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"xFLVAv36","properties":{"formattedCitation":"\\super 32\\nosupersub{}","plainCitation":"32","noteIndex":0},"citationItems":[{"id":939,"uris":[""],"uri":[""],"itemData":{"id":939,"type":"article-journal","abstract":"Purpose: The purpose of this study is to establish the validity of intracerebral hemorrhage (ICH) diagnoses in the Danish Stroke Registry (DSR) and the Danish National Patient Registry (DNPR).\nPatients and methods: We estimated the positive predictive value (PPV) of ICH diagnoses for a sample of 500 patients from the DSR (patients recorded under ICH diagnosis) and DNPR (International Classification of Diseases, version 10, code I61) during 2010-2015, using discharge summaries and brain imaging reports (minimal data). We estimated PPVs for any ICH (a-ICH) and spontaneous ICH (s-ICH) alone. Furthermore, we assessed PPVs according to whether patients were recorded in both or only one of the registries. Finally, in a subsample with ICH diagnoses with access to full medical records and original imaging studies (extensive data, n=100), we compared s-ICH diagnosis and hemorrhage location after use of extensive vs minimal data.\nResults: In the DSR, the PPVs were 94% (95% CI, 91%-96%) for a-ICH and 85% (95% CI, 81%-88%) for s-ICH. In the DNPR, the PPVs were 88% (95% CI, 84%-91%) for a-ICH and 75% (95% CI, 70%-79%) for s-ICH. PPVs for s-ICH for patients recorded in both registries, DSR only, and DNPR only were 86% (95% CI, 82-99), 80% (95%CI, 71-87), and 49% (95%CI, 39-59), respectively. Evaluation of extensive vs minimal data verified s-ICH diagnosis in 98% and hemorrhage location in 94%.\nConclusion: The validity of a-ICH diagnoses in DSR and DNPR is sufficiently high to support their use in epidemiologic studies. For s-ICH, validity was high in DSR. In DNPR, s-ICH validity was lower, markedly so for the small subgroup of patients only recorded in this registry. Minimal data including discharge summaries and brain imaging reports were feasible and valid for identifying ICH location.","container-title":"Clinical Epidemiology","DOI":"10.2147/CLEP.S167576","ISSN":"1179-1349","journalAbbreviation":"Clin Epidemiol","language":"eng","note":"PMID: 30123006\nPMCID: PMC6086098","page":"941-948","source":"PubMed","title":"Intracerebral hemorrhage: positive predictive value of diagnosis codes in two nationwide Danish registries","title-short":"Intracerebral hemorrhage","volume":"10","author":[{"family":"Hald","given":"Stine Munk"},{"family":"Kring Sloth","given":"Christine"},{"family":"Hey","given":"Sabine Morris"},{"family":"Madsen","given":"Charlotte"},{"family":"Nguyen","given":"Nina"},{"family":"García Rodríguez","given":"Luis Alberto"},{"family":"Al-Shahi Salman","given":"Rustam"},{"family":"M?ller","given":"S?ren"},{"family":"Poulsen","given":"Frantz Rom"},{"family":"Potteg?rd","given":"Anton"},{"family":"Gaist","given":"David"}],"issued":{"date-parts":[["2018"]]}}}],"schema":""} 32 It could be argued that a more optimal approach would have been to evaluate the entire medical record of each patient and re-evaluate the original brain imaging studies. We evaluated this more extensive and logistically challenging approach in a small sample of patients (n=100) in a previous study, and found it produced highly similar results to those achieved with the more limited data approach used in the present study, both with regard to a-ICH/s-ICH status and ICH location. ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"IScFJwZH","properties":{"formattedCitation":"\\super 32\\nosupersub{}","plainCitation":"32","noteIndex":0},"citationItems":[{"id":939,"uris":[""],"uri":[""],"itemData":{"id":939,"type":"article-journal","abstract":"Purpose: The purpose of this study is to establish the validity of intracerebral hemorrhage (ICH) diagnoses in the Danish Stroke Registry (DSR) and the Danish National Patient Registry (DNPR).\nPatients and methods: We estimated the positive predictive value (PPV) of ICH diagnoses for a sample of 500 patients from the DSR (patients recorded under ICH diagnosis) and DNPR (International Classification of Diseases, version 10, code I61) during 2010-2015, using discharge summaries and brain imaging reports (minimal data). We estimated PPVs for any ICH (a-ICH) and spontaneous ICH (s-ICH) alone. Furthermore, we assessed PPVs according to whether patients were recorded in both or only one of the registries. Finally, in a subsample with ICH diagnoses with access to full medical records and original imaging studies (extensive data, n=100), we compared s-ICH diagnosis and hemorrhage location after use of extensive vs minimal data.\nResults: In the DSR, the PPVs were 94% (95% CI, 91%-96%) for a-ICH and 85% (95% CI, 81%-88%) for s-ICH. In the DNPR, the PPVs were 88% (95% CI, 84%-91%) for a-ICH and 75% (95% CI, 70%-79%) for s-ICH. PPVs for s-ICH for patients recorded in both registries, DSR only, and DNPR only were 86% (95% CI, 82-99), 80% (95%CI, 71-87), and 49% (95%CI, 39-59), respectively. Evaluation of extensive vs minimal data verified s-ICH diagnosis in 98% and hemorrhage location in 94%.\nConclusion: The validity of a-ICH diagnoses in DSR and DNPR is sufficiently high to support their use in epidemiologic studies. For s-ICH, validity was high in DSR. In DNPR, s-ICH validity was lower, markedly so for the small subgroup of patients only recorded in this registry. Minimal data including discharge summaries and brain imaging reports were feasible and valid for identifying ICH location.","container-title":"Clinical Epidemiology","DOI":"10.2147/CLEP.S167576","ISSN":"1179-1349","journalAbbreviation":"Clin Epidemiol","language":"eng","note":"PMID: 30123006\nPMCID: PMC6086098","page":"941-948","source":"PubMed","title":"Intracerebral hemorrhage: positive predictive value of diagnosis codes in two nationwide Danish registries","title-short":"Intracerebral hemorrhage","volume":"10","author":[{"family":"Hald","given":"Stine Munk"},{"family":"Kring Sloth","given":"Christine"},{"family":"Hey","given":"Sabine Morris"},{"family":"Madsen","given":"Charlotte"},{"family":"Nguyen","given":"Nina"},{"family":"García Rodríguez","given":"Luis Alberto"},{"family":"Al-Shahi Salman","given":"Rustam"},{"family":"M?ller","given":"S?ren"},{"family":"Poulsen","given":"Frantz Rom"},{"family":"Potteg?rd","given":"Anton"},{"family":"Gaist","given":"David"}],"issued":{"date-parts":[["2018"]]}}}],"schema":""} 32 Second, although we used multiple sources to identify all adult patients with ICH, it is likely that some patients were not captured by our hospital-based method. We did not identify patients with ICH that died before reaching hospital. As the rate of autopsy in Denmark is quite low, ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"wi8rPtUB","properties":{"formattedCitation":"\\super 54\\nosupersub{}","plainCitation":"54","noteIndex":0},"citationItems":[{"id":1177,"uris":[""],"uri":[""],"itemData":{"id":1177,"type":"article-journal","abstract":"New techniques have influenced the attitude to the autopsy and contribute to a de-emphasis on the importance of post-mortem examination. Since 1990, new Danish legislation has provoked a dramatic fall in the autopsy rate, which had already declined from 45% in 1970 to 35% in 1980. In the first half of 1990 the rate was 24% in the second half of that same year it had fallen to 16% (\nSOURCE: The Danish National Institute of Health, 1992). The clinicians now seem to manage without the autopsy to confirm or correct their daily diagnostics. They also seem to be of the opinion that they do well without this \"final checklist\". The autopsy, however, is still an important tool in understanding, correcting and improving future diagnosis. Therefore, post-mortems should again be carried out as a matter of course and common practice. The following proposals are all aimed at obtaining a higher autopsy rate: The 1990 legislation on autopsy should be changed so that permission to perform a post-mortem can be given in due time, before the supposed death, preferably by the patient himself and obviously with the right to a subsequent change of mind. It is of great importance that the Public Health Service informs both the public and health workers in general about the nature and importance of the autopsy. Likewise, doctors and health workers in general should be educated in how best to give information to patients. Pathologists should, through a more uniform and exact practice, encourage the clinicians to a renewal of the close collaboration concerning the facts revealed by the autopsy, both in their everyday practice and in scientific projects in general.","container-title":"Quality Assurance in Health Care: The Official Journal of the International Society for Quality Assurance in Health Care","DOI":"10.1093/intqhc/5.4.315","ISSN":"1040-6166","issue":"4","journalAbbreviation":"Qual Assur Health Care","language":"eng","note":"PMID: 8018889","page":"315-318","source":"PubMed","title":"Decrease in the frequency of autopsies in Denmark after the introduction of a new autopsy act","volume":"5","author":[{"family":"Petri","given":"C. N."}],"issued":{"date-parts":[["1993",12]]}}}],"schema":""} 54 supplementing our data with information from the Cause-of-Death Registry would most likely not improve our estimates to any measurable degree with regard to this source of bias. Our data sources did not include information on patients suspected of suffering an ICH that were not referred to hospital for evaluation. However, in Denmark, patients suspected of stroke, regardless of age, are considered medical emergencies and are therefore almost invariably promptly referred/transferred to hospital for evaluation. Based on our clinical experience, we therefore believe that the magnitude of this selection bias is relatively small. Third, some patients with ICH may have been incorrectly coded under non-ICH diagnoses. Previous Danish studies reported a very low degree of misclassification of ICH coded as other types of stroke or intracranial hemorrhage. ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"zBM0nZdd","properties":{"formattedCitation":"\\super 6,12,32,55\\nosupersub{}","plainCitation":"6,12,32,55","noteIndex":0},"citationItems":[{"id":104,"uris":[""],"uri":[""],"itemData":{"id":104,"type":"article-journal","abstract":"OBJECTIVE: To estimate the risk of occurrence of subarachnoid haemorrhage in first degree relatives (parents, siblings, children) of patients with subarachnoid haemorrhage.\nDESIGN: Population based cohort study using data from the Danish National Discharge Registry and the Central Person Registry.\nSUBJECTS: Incident cases of subarachnoid haemorrhage admitted to hospital from 1977 to 1995 (9367 patients) and their first degree relatives (14 781).\nMAIN OUTCOME MEASURES: The incidence rate of subarachnoid haemorrhage was determined for the relatives and compared with that of the entire population, standardised for age, sex, and calendar period. This process was repeated for patients discharged from neurosurgery units, as diagnoses from these wards had high validity (93%).\nRESULTS: 18 patients had a total of 19 first degree relatives with subarachnoid haemorrhage during the study period, corresponding to a standardised incidence ratio of 2.9 (95% confidence interval 1.9 to 4.6). Patients discharged from neurosurgery wards had a higher standardised incidence ratio (4.5, 2.7 to 7.3).\nCONCLUSIONS: First degree relatives of patients with subarachnoid haemorrhage have a threefold to fivefold increased risk of subarachnoid haemorrhage compared with the general population.","container-title":"BMJ (Clinical research ed.)","ISSN":"0959-8138","issue":"7228","journalAbbreviation":"BMJ","language":"eng","note":"PMID: 10634731\nPMCID: PMC27258","page":"141-145","source":"PubMed","title":"Risk of subarachnoid haemorrhage in first degree relatives of patients with subarachnoid haemorrhage: follow up study based on national registries in Denmark","title-short":"Risk of subarachnoid haemorrhage in first degree relatives of patients with subarachnoid haemorrhage","volume":"320","author":[{"family":"Gaist","given":"D."},{"family":"Vaeth","given":"M."},{"family":"Tsiropoulos","given":"I."},{"family":"Christensen","given":"K."},{"family":"Corder","given":"E."},{"family":"Olsen","given":"J."},{"family":"S?rensen","given":"H. T."}],"issued":{"date-parts":[["2000",1,15]]}}},{"id":1164,"uris":[""],"uri":[""],"itemData":{"id":1164,"type":"article-journal","abstract":"BACKGROUND: We wished to examine the impact of antiplatelet drug discontinuation on recurrent stroke and all-cause mortality.\nMETHODS: We identified a cohort of incident ischaemic stroke patients in a Danish stroke registry, 2007-2011. Using population-based registries we assessed subjects' drug use and followed them up for stroke recurrence, or all-cause death. Person-time was classified by antiplatelet drug use into current use, recent use (≤150 days after last use), and non-use (>150 days after last use). Lipid-lowering drug (LLD) use was classified by the same rules. We used Cox proportional hazard models to calculate the adjusted hazard ratio (HR) and corresponding 95% confidence intervals (CIs) for the risk of recurrent stroke or death associated with discontinuation of antiplatelet or LLD drugs.\nRESULTS: Among 4,670 stroke patients followed up for up a median of 1.5 years, 237 experienced a second stroke and 600 died. Compared with current antiplatelet drug use, both recent use (1.3 (0.8-2.0)), and non-use (1.3 (0.8-1.9)) were associated with increased recurrent stroke risk. The corresponding HRs of death were 1.9 (1.4-2.5) for recent and 1.8 (1.4-2.3) for non-use of antiplatelet drugs. Recent statin use was associated with markedly increased risk of death (2.1 (1.7-2.6)), and only marginally with recurrent stroke (1.2 (0.9-1.6)).\nCONCLUSIONS: Antiplatelet drug discontinuation may be associated with an increased recurrent stroke risk. Our results on death risk indicate that non-pharmacological biases, such as 'sick stopper', may threaten the validity of this risk estimate.","container-title":"Neuroepidemiology","DOI":"10.1159/000365732","ISSN":"1423-0208","issue":"1","journalAbbreviation":"Neuroepidemiology","language":"eng","note":"PMID: 25323533","page":"57-64","source":"PubMed","title":"Discontinuation of antiplatelet treatment and risk of recurrent stroke and all-cause death: a cohort study","title-short":"Discontinuation of antiplatelet treatment and risk of recurrent stroke and all-cause death","volume":"43","author":[{"family":"?stergaard","given":"Kamilla"},{"family":"Potteg?rd","given":"Anton"},{"family":"Hallas","given":"Jesper"},{"family":"Bak","given":"S?ren"},{"family":"Christensen","given":"René","non-dropping-particle":"dePont"},{"family":"Gaist","given":"David"}],"issued":{"date-parts":[["2014"]]}}},{"id":939,"uris":[""],"uri":[""],"itemData":{"id":939,"type":"article-journal","abstract":"Purpose: The purpose of this study is to establish the validity of intracerebral hemorrhage (ICH) diagnoses in the Danish Stroke Registry (DSR) and the Danish National Patient Registry (DNPR).\nPatients and methods: We estimated the positive predictive value (PPV) of ICH diagnoses for a sample of 500 patients from the DSR (patients recorded under ICH diagnosis) and DNPR (International Classification of Diseases, version 10, code I61) during 2010-2015, using discharge summaries and brain imaging reports (minimal data). We estimated PPVs for any ICH (a-ICH) and spontaneous ICH (s-ICH) alone. Furthermore, we assessed PPVs according to whether patients were recorded in both or only one of the registries. Finally, in a subsample with ICH diagnoses with access to full medical records and original imaging studies (extensive data, n=100), we compared s-ICH diagnosis and hemorrhage location after use of extensive vs minimal data.\nResults: In the DSR, the PPVs were 94% (95% CI, 91%-96%) for a-ICH and 85% (95% CI, 81%-88%) for s-ICH. In the DNPR, the PPVs were 88% (95% CI, 84%-91%) for a-ICH and 75% (95% CI, 70%-79%) for s-ICH. PPVs for s-ICH for patients recorded in both registries, DSR only, and DNPR only were 86% (95% CI, 82-99), 80% (95%CI, 71-87), and 49% (95%CI, 39-59), respectively. Evaluation of extensive vs minimal data verified s-ICH diagnosis in 98% and hemorrhage location in 94%.\nConclusion: The validity of a-ICH diagnoses in DSR and DNPR is sufficiently high to support their use in epidemiologic studies. For s-ICH, validity was high in DSR. In DNPR, s-ICH validity was lower, markedly so for the small subgroup of patients only recorded in this registry. Minimal data including discharge summaries and brain imaging reports were feasible and valid for identifying ICH location.","container-title":"Clinical Epidemiology","DOI":"10.2147/CLEP.S167576","ISSN":"1179-1349","journalAbbreviation":"Clin Epidemiol","language":"eng","note":"PMID: 30123006\nPMCID: PMC6086098","page":"941-948","source":"PubMed","title":"Intracerebral hemorrhage: positive predictive value of diagnosis codes in two nationwide Danish registries","title-short":"Intracerebral hemorrhage","volume":"10","author":[{"family":"Hald","given":"Stine Munk"},{"family":"Kring Sloth","given":"Christine"},{"family":"Hey","given":"Sabine Morris"},{"family":"Madsen","given":"Charlotte"},{"family":"Nguyen","given":"Nina"},{"family":"García Rodríguez","given":"Luis Alberto"},{"family":"Al-Shahi Salman","given":"Rustam"},{"family":"M?ller","given":"S?ren"},{"family":"Poulsen","given":"Frantz Rom"},{"family":"Potteg?rd","given":"Anton"},{"family":"Gaist","given":"David"}],"issued":{"date-parts":[["2018"]]}}},{"id":213,"uris":[""],"uri":[""],"itemData":{"id":213,"type":"article-journal","abstract":"PURPOSE: This study aimed to assess the usefulness of Danish patient registers for epidemiological studies of subdural hematoma (SDH) and to describe clinical characteristics of validated cases.\nMETHODS: Using a patient register covering a geographically defined area in Denmark, we retrieved hospital contacts recorded under SDH International Classification of Diseases version 10 codes S065 and I620 in 2000-2012. Neurosurgeons reviewed medical records of all potential cases. Based on brain scan results, verified cases were classified by SDH type (chronic SDH (cSDH) or acute SDH (aSDH)). Thirty-day mortality and preadmission antithrombotic drug use were established through linkage to population-based registers. We calculated the positive predictive value of the SDH code and compared mortality and preadmission antithrombotic drug use of cSDH with those of aSDH (age-adjusted and sex-adjusted odds ratio (OR), 95% confidence interval (95%CI)).\nRESULTS: We verified the diagnosis in 936 of 1185 identified patients. The positive predictive value was highest for hospital contacts with principal discharge diagnosis code S065 (96%) but was low for other contact types under code S065 (25-54%), and only moderate for patients recorded under code I620 (62%). cSDH represented 57% of verified cases, and aSDH the remaining 43%. cSDH differed markedly from aSDH with regard to a number of clinical characteristics, including a much lower mortality (OR 0.2, 95%CI 0.1-0.3). However, preadmission antithrombotic drug use did not vary by SDH type (OR 0.9, 95%CI 0.6-1.2).\nCONCLUSIONS: Danish patient registers are a useful resource for SDH studies. However, choice of International Classification of Diseases code markedly influences diagnostic validity. Distinction between cSDH and aSDH is not possible based on SDH diagnosis codes only. Copyright ? 2016 John Wiley & Sons, Ltd.","container-title":"Pharmacoepidemiology and Drug Safety","DOI":"10.1002/pds.4058","ISSN":"1099-1557","issue":"11","journalAbbreviation":"Pharmacoepidemiol Drug Saf","language":"ENG","note":"PMID: 27384945","page":"1253-1262","source":"PubMed","title":"Subdural hematoma cases identified through a Danish patient register: diagnosis validity, clinical characteristics, and preadmission antithrombotic drug use","title-short":"Subdural hematoma cases identified through a Danish patient register","volume":"25","author":[{"family":"Poulsen","given":"Frantz Rom"},{"family":"Halle","given":"Bo"},{"family":"Potteg?rd","given":"Anton"},{"family":"García Rodríguez","given":"Luis Alberto"},{"family":"Hallas","given":"Jesper"},{"family":"Gaist","given":"David"}],"issued":{"date-parts":[["2016",7,7]]}}}],"schema":""} 6,12,32,55 Our calculation of sensitivity is based on the assumption that patients with true ICH would have an ICH code in at least one of the studied data sources. We do not know how often physicians diagnosing ICH accidentally use non-cerebrovascular disorder codes but judging by data on the reverse situation in our study (ie, patients with other diagnoses coded as ICH), this scenario is rare. Fourth, our more inclusive approach with regard to diagnostic criteria is debatable. We used the WHO criteria for stroke, but in addition accepted inclusion of patients based on symptoms (eg, severe sudden onset headache), where imaging supported new onset ICH. Our more inclusive approach could potentially hamper comparison with previous studies based exclusively on WHO criteria. However, as more than 96% of cases included in this study also fulfilled the WHO criteria, we believe that use of our criteria, while more accurately reflecting current clinical practice, had little impact on the comparability of our results with those of previous studies. Our criteria also diverged from the original, strictly clinical WHO criteria in that we only included patients with available neuroimaging results. However, routine use of neuroimaging in cases suspected of stroke is widely available at all hospitals in Denmark. Also, neuroimaging results made it possible to classify the location of ICH, a practice encouraged in updated criteria for population-based studies of ICH. ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"JeE05qmT","properties":{"formattedCitation":"\\super 56\\nosupersub{}","plainCitation":"56","noteIndex":0},"citationItems":[{"id":1214,"uris":[""],"uri":[""],"itemData":{"id":1214,"type":"article-journal","container-title":"Stroke","DOI":"10.1161/STROKEAHA.118.022161","ISSN":"1524-4628","issue":"9","journalAbbreviation":"Stroke","language":"eng","note":"PMID: 30355005","page":"2248-2255","source":"PubMed","title":"Updated Criteria for Population-Based Stroke and Transient Ischemic Attack Incidence Studies for the 21st Century","volume":"49","author":[{"family":"Feigin","given":"Valery"},{"family":"Norrving","given":"Bo"},{"family":"Sudlow","given":"Cathie L. M."},{"family":"Sacco","given":"Ralph L."}],"issued":{"date-parts":[["2018"]]}}}],"schema":""} 56 Fifth, the generalizability of our study results at a national level can be questioned, as we only included data from one of the five regions in Denmark. However, patients with stroke are treated in accordance to the national guidelines in all of Denmark ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"YDSxVY66","properties":{"formattedCitation":"\\super 57\\nosupersub{}","plainCitation":"57","noteIndex":0},"citationItems":[{"id":218,"uris":[""],"uri":[""],"itemData":{"id":218,"type":"article","language":"Danish","publisher":"Danish Stroke Society","title":"Referenceprogram for behandling af patienter med apopleksi og TCI (2013)","URL":" uploads/REFERENCEPROGRAMFINAL20131.pdf","author":[{"family":"Ref.program","given":""}],"issued":{"date-parts":[["2013"]]}}}],"schema":""} 57 and RSD is representative of the Danish population with regard to demographic characteristics, healthcare utilization, and medication use. ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"ipIHVe0G","properties":{"formattedCitation":"\\super 58\\nosupersub{}","plainCitation":"58","noteIndex":0},"citationItems":[{"id":1179,"uris":[""],"uri":[""],"itemData":{"id":1179,"type":"article-journal","abstract":"BACKGROUND: While Denmark is well known for its plethora of registers. Many studies are conducted on research databases that only cover parts of Denmark, and regional differences could potentially threaten these studies' external validity. The aim of this study was to assess sociodemographic and health related homogeneity of the five Danish regions.\nMETHODS: We obtained descriptive data for the five Danish regions, using publicly available data sources: Statbank Denmark, the Danish Ministry of Economic Affairs, and Medstat.dk. These data sources comprise aggregate data from four different nationwide registers: The Danish National Patient Register, The Danish Civil Registration System, The Danish Register of Medicinal Product Statistics, and The Danish National Health Service Register for Primary Care. We compared the Danish regions regarding demographic and socioeconomic characteristics, health care utilization, and use of medication. For each characteristic, one-year prevalence was obtained and analyses were performed for 2013 and 2008 to account for possible change over time.\nRESULTS: In 2013, 5,602,628 persons were living in Denmark. The mean age was 40.7 years in the entire Danish population and ranged between 39.6 to 42.4 years in the five regions (coefficient of variation between regions [CV] = 0.028). The proportion of women in Denmark was 50.4% (CV = 0.009). The proportion of residents with low education level was 28.7% (CV = 0.051). The annual number of GP contacts was 7.1 (range: 6.7-7.4, CV = 0.040), and 114 per 1,000 residents were admitted to the hospital (range: 101-131, CV = 0.107). The annual number of persons redeeming a prescription of any medication was 723 per 1,000 residents (range: 718-743, CV = 0.016). Analyses for 2008 showed comparable levels of homogeneity as for 2013.\nCONCLUSIONS: We found substantial homogeneity between all of the five Danish regions with regard to sociodemographic and health related characteristics. Epidemiologic studies conducted on regional subsets of Danish citizens have a high degree of generalizability.","container-title":"PloS One","DOI":"10.1371/journal.pone.0140197","ISSN":"1932-6203","issue":"10","journalAbbreviation":"PLoS ONE","language":"eng","note":"PMID: 26439627\nPMCID: PMC4595085","page":"e0140197","source":"PubMed","title":"Comparison of the Five Danish Regions Regarding Demographic Characteristics, Healthcare Utilization, and Medication Use--A Descriptive Cross-Sectional Study","volume":"10","author":[{"family":"Henriksen","given":"Daniel Pilsgaard"},{"family":"Rasmussen","given":"Lotte"},{"family":"Hansen","given":"Morten Rix"},{"family":"Hallas","given":"Jesper"},{"family":"Potteg?rd","given":"Anton"}],"issued":{"date-parts":[["2015"]]}}}],"schema":""} 58 Finally, we excluded patients with untraced medical records, which may have influenced our estimates of validity of ICH coding. However, as patients from this group comprised less than 5% of the entire sample, and additional analyses made it most likely that PPV was high among untraced cases, we find it unlikely that this factor had other than a minor impact on our results.ConclusionIn our study, based on all identifiable consecutive cases of first-time ever ICH in a defined Danish population –irrespective of clinical severity and mode of hospital contact– we found that the validity of a-ICH diagnoses was high in both DSR and DNPR. With regard to s-ICH, data in DSR were more valid, but less complete than DNPR data. Our results can provide guidance for the future use of these data sources for research (eg, cohort and case-control studies, time-series, before-and-after studies) of ICH and clinical practice (eg, audit purposes, evaluation of services). AcknowledgmentsThe authors wish to thank Jan Helldén, Department of Business Intelligence, RSD for contributing to the collection of the data. The authors also wish to thank the staff in the Danish Clinical Quality Program – National Clinical Registries (RKKP) and the Danish Stroke Registry for their work in data collection and delivery.Author contributionsSMH and DG conceived the study, performed the analyses, and wrote the first draft. All authors contributed to data analysis, drafting or revising the article, have agreed on the journal to which the article will be submitted, gave final approval of the version to be published, and agree to be accountable for all aspects of the work. FundingThis work is part of a PhD fellowship (SMH) supported by the University of Southern Denmark and the Region of Southern Denmark. The project also received funding from Odense University Hospital (A2926; 70-A3187; 49-A2483) and the A.P.M?ller amd Chastine Mc-Kinney M?ller Foundation (18-L-0214). DisclosureThe activities of DG are supported by a grant from Odense University Hospital. 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Comparison of the Five Danish Regions Regarding Demographic Characteristics, Healthcare Utilization, and Medication Use--A Descriptive Cross-Sectional Study. PLoS ONE. 2015;10(10):e0140197. doi:10.1371/journal.pone.0140197Table 1. Underlying diagnoses in non-verified cases and in verified cases not classified as spontaneous ICH.NON-VERIFIED CASES Number (%)(n=1,192)ICH present, but did not fulfill study criteria 515 (43.2)ICH, traumatic268Acute ischemic stroke with hemorrhagic transformation123ICH, thrombolysis-related53ICH due to subarachnoid hemorrhage24ICH, periprocedurala 21ICH suspected, but patient died before scan 18History of ICH (predating study period)8Intracranial hemorrhage other than ICH396 (33.2)Subarachnoid hemorrhageb 205Subdural hematoma152Traumatic intracranial hemorrhage, multiple sites21History of intracranial hemorrhage10Epidural hematoma8Ischemic and other cerebrovascular diagnoses115 (9.7)Acute ischemic stroke99TIA8Other cerebrovascular disordersc 8Various166 (13.9)ICH or intracranial bleed suspected; ruled out by brain scan41Cerebral microbleedsd13Seizure11Headache, syncope, or vertigo11Cerebral tumour9Various coding errorse 81VERIFIED CASES WITH NON-SPONTANEOUS ICH,f UNDERLYING CAUSENumber (%)(n=225)Brain tumour105 (46.7)Arteriovenous malformation61 (27.1)Cavernous hemangioma41 (18.2)Cerebral sinus thrombosis 7 (3.1)Dural arteriovenous fistula6 (2.7)Various rare causesg5 (2.2)Abbreviation: ICH: intracerebral hemorrhageaeg, ventricular catheter insertionbNumber of patients with aneurysmal/traumatic/unspecified: 110/57/38ceg, transient global amnesia, cerebral sinus thrombosis.dNo coexisting ICH or any other intracranial hemorrhagee1-2 patients recorded per code under these primarily (>70%) non-neurological codes. fClassified as ‘any ICH’ but not ‘spontaneous ICH’.g Not specified to preserve anonymity. Table 2 Positive predictive value of admission codes for ICH in Danish National Patient Registry (DNPR) and Danish Stroke Registry (DSR). No. retrievedNo. verifiedPPV (95% CI)Any ICHSpontaneous ICHAny ICHSpontaneous ICHDNPR – inpatient diagnosisPrimary diagnostic positiona31692414222676.2 (74.7-77.6)70.2 (68.6-71.8)Other than primary diagnostic positionb63231227649.4 (45.5-53.3)43.7 (39.9-47.6)Any diagnostic positionc38012726250271.7 (70.3-73.1)65.8 (64.3-67.3)DSR24432113199886.5 (85.1-87.8)81.8 (80.2-83.3)Abbreviations: ICH: intracerebral hemorrhage; PPV: positive predictive valueaIncludes 2,116 patients concurrently recorded in DSR. bIncludes 240 patients concurrently recorded in DSR. cIncludes 2,356 patients concurrently recorded in DNPR.Table 3 Number of patients identified and number of verified diagnoses of ICH by type of contact in Danish National Patient Registry (DNPR) and by concurrent recording in Danish Stroke Registry (DSR). Patients with first-ever hospital contact with intracerebral hemorrhage codes, Region of Southern Denmark 2009-2017(n=3,956)DNPRDNPRa or DSRInpatient, primary diagnostic positionInpatient, diagnostic position other than primaryOutpatient/ED only,b any diagnostic positionDSR onlyb Record in DSRcNo record in DSRdRecord in DSRcNo record in DSRdNumber retrieved2116105324039268873956Any-ICH diagnosis confirmedNumber18745402061065332764PPV (95% CI)88.6 (87.1-89.9)51.3 (48.3-54.3)85.8 (80.9-89.7)27.0 (22.9-31.6)7.4 (3.2-16.1)37.9 (28.5-48.4)69.9 (68.4-71.3)Spontaneous-ICH confirmedNumber1771455195815322539PPV (95% CI)83.7 (82.1-85.2)43.2 (40.2-46.2)81.3 (75.8-85.7)20.7 (16.9-24.9)7.4 (3.2-16.1)36.8 (27.4-47.3)64.2 (62.7-65.7)Abbreviations: ED: emergency department; ICH: intracerebral hemorrhage; PPV: positive predictive valueWe regarded consecutive hospital contacts coded for ICH and with a gap of no more than 7 days as belonging to the same episode of ICH. aDNPR inpatient, outpatient, or ED – any positionbNo concurrent inpatient record in DNPR. cConcurrent record in DSR.dNo concurrent record in DSR.Table 4 PPV and sensitivity of inpatient first-ever codes for ICH in the Danish Stroke Registry and the Danish National Patient Registry stratified by year, age, and sex. Danish National Patient Registrya Danish Stroke RegistryAny ICHPPV (95%CI)Sensitivity (95%CI) PPV (95%CI)Sensitivity (95%CI) Periodb2009-201174.0 (71.2-76.6)86.7 (84.2-88.8)86.6 (84.1-88.8)83.7 (81.1-86.1)2012-201476.7 (74.1-79.2)90.0 (87.8-91.8)86.6 (84.1-88.8)75.9 (73.0-78.6)2015-201777.5 (75.0-79.9)85.6 (83.3-87.6)86.3 (83.8-88.4)70.7 (67.9-73.4)Ageb (years)<6474.9 (72.0-77.6)87.9 (85.4-90.0)88.2 (85.4-90.6)70.3 (66.9-73.4)65-7479.2 (76.2-81.9)87.5 (84.8-89.7)87.7 (84.9-90.0)77.5 (74.3-80.4)75+75.3 (73.1-77.5)86.9 (85.0-88.7)84.9 (82.8-86.9)79.4 (77.1-81.6)SexMen77.7 (75.6-79.6)87.4 (85.6-89.1)87.6 (85.6-89.3)77.7 (75.5-79.8)Women74.6 (72.4-76.7)87.2 (85.3-88.9)85.3 (83.2-87.2)74.9 (72.6-77.2)Spontaneous ICHPPV (95%CI)Sensitivity (95%CI) PPV (95%CI)Sensitivity (95%CI) Periodc2009-201169.8 (66.9-72.6)87.3 (84.8-89.4)82.8 (80.1-85.3)85.6 (83.0-87.9)2012-201469.2 (66.4-72.0)90.6 (88.4-92.5)79.9 (76.9-82.5)78.2 (75.2-80.9)2015-201771.6 (68.9-74.1)85.4 (83.1-87.6)82.6 (79.8-85.0)73.3 (70.4-76.0)Agec (years)<6463.8 (60.6-66.9)88.2 (85.5-90.4)79.4 (76.0-82.4)74.5 (71.1-77.7)65-7474.0 (70.9-77.0)88.4 (85.7-90.6)82.8 (79.7-85.6)79.2 (76.0-82.1)75+72.1 (69.8-74.4)87.0 (86.3-88.8)82.4 (80.2-84.5)80.6 (78.3-82.7)SexMen71.8 (69.6-74.0)87.7 (85.8-89.3)82.9 (80.7-84.9)79.8 (77.6-81.9)Women68.6 (66.3-70.9)87.7 (85.7-89.4)80.6 (78.2-82.7)77.5 (75.1-79.7)Abbreviations: CI: confidence interval; ICH: intracerebral hemorrhage; PPV: positive predictive valueaInpatient – primary diagnostic position codebChi-squared for trend: P>0.05cChi-squared for trend: P<0.001 Table 5 Sensitivity of inpatient first-ever codes for ICH in the Danish Stroke Registry and the Danish National Patient Registry stratified by year, age, and sex. Danish National Patient Registrya Any ICH2009-20112012-20142015-2017P-valuebWomen <75 years old87.2 (81.7-91.3)91.8 (86.8-94.9) 86.5 (81.4-90.3)>0.05Women ≥75 years old85.8 (80.7-89.8)86.4 (81.5-90.2)86.8 (82.2-90.3)>0.05Men <75 years old88.0 (83.7-91.3)91.1 (87.2-93.8)83.1 (78.5-86.8)>0.05Men ≥75 years old84.8 (78.2-89.6)91.1 (86.0-94.5)86.9 (81.6-90.8)>0.05Spontaneous ICH2009-20112012-20142015-2017Women <75 years old88.6 (82.9-92.6)94.0 (89.0-96.8)86.3 (80.8-90.4)>0.05Women ≥75 years old85.8 (80.6-89.8)86.8 (81.8-90.5)86.9 (82.2-90.5)>0.05Men <75 years old88.7 (84.4-92.0)92.0 (88.0-94.8)82.9 (78.1-86.8)0.03Men ≥75 years old85.2 (78.4-90.1)91.1 (85.8-94.5)86.6 (81.2-90.6)>0.05Danish Stroke RegistryAny ICH2009-20112012-20142015-2017P-valuebWomen <75 years old81.9 (75.8-86.8)72.0 (65.1-78.0)64.2 (57.8-70.1)<0.001Women ≥75 years old85.4 (80.2-89.4)79.0 (73.5-83.7)69.5 (63.8-74.7)<0.001Men <75 years old80.9 (75.9-85.1)74.2 (68.9-78.9)70.3 (65.0-75.1)0.029Men ≥75 years old89.4 (83.5-93.4)78.3 (71.8-83.7)80.6 (74.6-85.4)0.046Spontaneous ICH2009-20112012-20142015-2017Women <75 years old85.0 (78.8-89.6)76.0 (68.6-82.1)68.5 (61.7-64.6)<0.001Women ≥75 years old86.3 (81.1-90.2)79.5 (73.9-84.2)71.0 (65.2-76.2)<0.001Men <75 years old82.7 (77.7-86.8)77.2 (71.6-82.0)72.7 (67.3-77.6)0.005Men ≥75 years old90.8 (85.0-94.6)79.8 (73.1-85.1)81.6 (75.7-86.3)0.035Abbreviations: CI: confidence interval; ICH: intracerebral hemorrhage; PPV: positive predictive valueaInpatient – primary diagnostic position codebChi-squared for trendTable 6 Distribution of patients with untraceable medical records by year and contact recorded in Danish National Patient Registry (DNPR) and/or Danish Stroke Registry (DSR). Number (%) of patients PeriodDNPR inpatient contact & DSRaAny other contactbAll2009-201180 (73.4)36 (26.6)1162012-201429 (54.7)28 (45.3)572015-2017<5NRc (>75%)20*Percentage not calculated for counts less than 5 to preserve anonymity. aConcurrently recorded in Danish National Patient Registry (DNPR) as inpatient (ICH code at any diagnostic position) and Danish Stroke Registry (DSR)bCorresponds to (a) patients with records in DNPR (inpatient, emergency department or outpatient), but no concurrent record in DSR; and (b) patients with records in DSR only. cNot reported to preserve anonymity.Table 7 Distribution of patients with untraceable medical records by source, year, age and sex. Danish National Patient Registrya,bInpatient, primary diagnostic positionInpatient, diagnostic position other than primaryDanish Stroke RegistrycRetrieved, including untracedUntraced,d no. (%)Retrieved including untracedUntraced,d no. (%)Retrieved including untracedUntraced,d no. (%)Period2009-20111093100 (9.1)6009 (1.5)1,81084 (4.6)2012-2014109141 (3.8)62112 (1.9)1,63432 (2.0)2015-2017114519 (1.7)7380 (0)1,680<5 (NRe)Age (years)<6494140 (4.3)5648 (1.4)1,27224 (1.9)65-7482633 (4.0)525<5 (--*)1,31824 (1.8)75+156287 (5.6)87010 (1.1)2,53471 (2.8)SexMen169693 (5.5)1,01710 (1.0)2,66870 (2.6)Women163367 (4.1)94211 (1.2)2,45649 (2.0)*Percentage not calculated for counts less than 5 to preserve anonymity. aDoes not include cases with ICH codes recorded in the Danish National Patient Registry with contacts classified as outpatient/emergency department contact only (retrieved/untraced: 73/5).bPatients concurrently recorded in Danish Stroke Registry includedcPatients concurrently recorded in Danish National Patient Registry includeddDischarge letter and brain scan report could not be traced, primarily due to incompleteness of archives for pre-EMR medical records at certain hospitals in the catchment area.eNot reported to preserve anonymity.Table 8 Location of spontaneous intracerebral hemorrhage. Single ICH(n=2,430)Multiple ICH(n=109)All ICH(n=2,539)LocationNumber%Number%Number%Lobar91437.67770.699139.0Deep83934.51311.985233.6Infratentorial32113.21412.833513.2Unclassifiable – large27911.50027911.0Isolated intraventricular hemorrhage482.0NANA481.9Insufficient information291.254.6341.3Figure 1. Identification of patient records for validation from the DSR and the DNPR. ................
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