University of Washington



Formulating a PICO question – surrogate endpoints -The formulation of a clinical question requires specification of the Patient characteristics (P), the Intervention (I), the Control (C), and the Outcome(O). The acronym PICO is sometimes used to refer to these 4 elements of the scientific question. In the following clinical questions, identify the four elements (PICO), and write “not specified” for the elements of the PICO question that are missing. Don’t make assumptions when identifying the elements of PICO.Example; Consider the following clinical question: "Does long-term therapy with chin cup result in TMJ problem?" Rephrase this question in PICO format and indicate which aspect is missing.Answer:P: not specifiedI : chin cupC: not specifiedO: TMJ problem(For the following 10 questions, read the clinical question (in bold) and see if you can figure out the different elements of PICO. The answers are provided so you may want to cover up the answers and test yourself.1. How does bleaching affect patients who have active caries and/or are considered high risk for caries?P: patients who have active caries and/or are considered high risk for cariesI:bleachingC:not specifiedO:not specified2. For a patient with periodontitis, generalized bone loss and deep pockets, does adding deep cleaning + Chlorhexidine rinse help obtain better resultsP:patient with periodontitis, generalized bone loss and deep pocketsI:deep cleaning + Chlorhexidine rinseC: not specifiedO:not specified3. In patients with TMD, does the addition of an anterior ramp increase the effectiveness of the occlusal guard?P:patient with TMDI:anterior rampC: not specifiedO:not specified4. In patients with a localized vestibular swelling due to spread of an endodontic infection, is incision and drainage alone an appropriate treatment, or should the patient also be described an antibiotic?P:patients with a localized vestibular swelling due to spread of an endodontic infectionI:I &DC: I & D + antibiotic (which antibiotic?)O:not specified5. In patients with a suspected pulpitis, which technique for cold testing is the most effective, ice, CO2, or tetrafluoroethane?P:patients with a suspected pulpitis I:iceC: CO2C2:tetrafluoroethaneO:not specified6. Does the NTI device have an effect on migraine incidence?P:not specified I:NTIC: not specifiedO:migraine incidence7. Does intranasal delivery of carbamazepine reduce the pain related to trigeminal neuralgia?P: patient with trigeminal neuralgiaI: intranasal delivery of carbamazepineC: not specifiedO: pain8. Will the use of calcium hydroxide solution be an effective irrigant in root canal treatment?P: not specified/patient with root canal treatment?I: calcium hydroxide solutionC: not specifiedO: not specified9. Is topical fluoride effective?P: not specifiedI: topical fluoride C: not specifiedO: not specified10. Is the zirconia reinforced ceramic crown a reliable alternative to the traditional metal-ceramic crown when it comes to restoring teeth?P: not specifiedI: zirconia reinforced ceramic crown C: metal-ceramic crownO: not specified11. Two treatments will be compared in periodontal patients with vertical bone loss: (1) collagen with incorporated BMP-2 and (2) treatment by guided tissue regeneration. The outcomes of interest are improvement of attachment level and bone formation in defects measured by radiographs. What element of the PICO question is described in a non-standard way? Circle the correct answer:PatientInterventionControlOutcome(correct answer: outcome - a pico question needs to focus on one specific outcome, not multiple outcomes. While clinical trials or epidemiological studies can be designed that focus on multiple outcomes, such studies are difficult to design and conduct. As a result, as a general rule of thumb try to focus on one outcome when specifying PICO).12. Please reformat this question in standard PICO format:P: women on osteoporosis medication (like fosamax)I: orthodontic treatment – comprehensiveC: women not taking Fosamax or any other osteoporosis medicationO: Root resorption-answerP: osteoporotic women undergoing orthodontic therapyI: fosamaxC: no osteoporosis medicationO: Root resorption13. Is the outcome in the following PICO question a surrogate or a true endpoint?P: Class II malocclusion and > 5 mm overjetI: early treatment with twin-block applianceC: no treatmentO: Class I occlusion 14. A periodontal treatment that results in improving probing pocket depth willprovide a tangible benefit to the patientresult in improved tooth retentionresult in improved chewingNone of the above15. Which of the following is a true endpoint (syn., a clinically relevant or meaningful outcome)(a) A 5 mm increase in probing pocket depth(b) A caries lesion detected by means of a radiograph(c) The genetic test-result identifying the IL-1 marker.(d) pain16. Tonsillectomy is a controversial surgical procedure that is sometimes recommended by orthodontists to alter facial growth. One of the goals of tonsillectomy is to prevent recurrent otitis media. A study published in a recent issue of the New England Medical Journal (Vol. 344, April 19, 2001) assessed the efficacy of tonsillectomy. Which of the following outcome measure in a clinical trial would be most convincing to assess efficacy of tonsillectomy (The correct answer to this question is also the measure that was used in the New England Medical Journal publication)(a) Bacteriological analysis of abscess causing pathogens in middle ear fluid (b) Prescription of antibiotics for otitis media(c) Hospitalization and operations related to otitis media(d) Diagnosis of re-infection with H. influenza, the primary etiology of otitis mediaChallenging questions on surrogate endpoints. These questions require advanced reading in this topic area.17. What two criteria need to be fulfilled for the surrogate (Class I occlusion) to be a valid surrogate for the true endpoint?Answer:1…Angle classification has to be informative on poor function2…The beneficial effect of orthodontic therapy on the improved function should be captured ( > 75%) by the Angle classification 18. In 1992, researchers at the University of Buffalo said they discovered a vaccine for preventing gum disease (Wall Street Journal, August 10, 1992). They discovered that injection of synthetic protein produced antibodies that interfered with the P. gingivalis bacterium binding to teeth.(a) Since the presence of P. gingivalis in a periodontal pocket doubles the risk for periodontal attachment loss (J Clin Perio, 1991, 18; 744-50), this vaccine will reduce tooth loss (b) Since the presence of P. gingivalis in a periodontal pocket doubles the risk for periodontal attachment loss (J Clin Perio, 1991, 18; 744-50), this vaccine will provide a clinically meaningful benefit to the patient.(c) a & b(d) None of the above ................
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