Health Funding Authority’s WIES5A Methodology and …
Ministry of Health
WIES8A Methodology
and
Casemix Purchase Unit Allocation
for the
2001/2002 Financial Year
Frozen Specification for implementation on NMDS
9 May 2001 with minor modifications on 3 August and 10 October 2001
Authors: Michael Rains[1]
James Hogan[2]
Marty de Boer[3]
Table of Contents
1 Introduction 4
1.1 Background 4
1.2 Changes from the WIES5A version for the 2000/2001 FY 5
1.2.1 Propagation of the current exclusion framework 5
1.3 Areas for change in the future 5
1.3.1 Exclusion rule Post Natal Early Intervention 5
1.3.2 Neonatal CPAP 5
1.3.3 Other possible exclusions 6
2 WIES8A calculation 7
2.1 Derived variables required in calculation 7
2.1.1 Length of Stay 7
2.1.2 Reallocated DRG 7
2.2 DRG Reallocations 7
2.2.1 AR-DRG A04, Bone Marrow Transplants 8
2.2.2 Adjustment for Peritoneal Dialysis 8
2.2.3 Adjustment of medical AR-DRGs with radiotherapy 8
2.2.4 All other AR-DRGs 8
2.3 Adjusted Mechanical Ventilation Days 8
2.3.1 DRGs excluded from mechanical ventilation days 9
2.3.2 Calculation of mechanical ventilation days from hours 9
2.3.3 Calculation of mechanical ventilation days without hours 9
2.4 General Calculation 9
2.4.1 Calculating WIES8A 11
2.4.2 Copayment for Mechanical Ventilation 12
2.4.3 Base WIES 13
2.4.4 Final WIES weight 15
3 HFA Purchase Unit allocation 15
3.1 Derived variables required in allocation 15
3.1.1 Patients Age 15
3.1.2 Length of Stay 15
3.2 Exclusions from casemix purchasing 15
3.2.1 Neonatal Inpatient Casemix Purchasing 15
3.2.2 Non- Medical/Surgical Purchasing 15
3.2.3 Non Base Funding Purchases 15
3.2.4 Designated Hospital Purchasing 15
3.2.5 Non-Treated Patients 15
3.2.6 Error DRGs 15
3.2.7 Some Transplants 15
3.2.8 Some Spinal Injuries 15
3.2.9 Surgical Termination of Pregnancy 15
3.2.10 Renal and Peritoneal Dialysis 15
3.2.11 Sameday Chemotherapy & Radiotherapy 15
3.2.12 Sleep Apnoea 15
3.2.13 Lithotripsy 15
3.2.14 Colposcopies 15
3.2.15 Cystoscopies 15
3.2.16 ERCPs 15
3.2.17 Colonoscopies 15
3.2.18 Gastroscopies 15
3.2.19 Bronchoscopies 15
3.2.20 Day Case Blood Transfusions 15
3.3 Mapping of Health Service Speciality codes to MoH casemix PUs 15
4 Appendices 15
4.1 Spreadsheet containing 01/02 FY DRG weights and associated variables for calculating WIES8A 15
4.2 SAS Code for Derivation of WIES8A 15
Introduction
This report specifies the final version of the 2001/2002 Financial Year[4] (01/02 FY) WIES8A methodology for casemix purchasing employed by the Ministry of Health. It is the same as the document for the 00/01 FY with adaptation to the new costweights, WIES8A, to be used in New Zealand from 1 July 2001. The original intent for this document was to specify the casemix methodology used by the Ministry so that case weighted discharges can be calculated for all National Minimum Dataset (NMDS) events by the New Zealand Health Information Service (NZHIS). Further variables are also required to identify casemix purchased Purchase Units (PUs), case complexity (for future costing work) and the costweight version used. A secondary purpose of this document is to provide a definitive explanation of Ministry casemix purchasing for use throughout the health sector. As such, additional information beyond that required by NZHIS for implementation on the NMDS is provided both as a background and to identify areas which may be subject to revision for future contracting.
As requested by NZHIS, the specification is described as much as possible in plain english. There are, however, also references to lists of International Classifications of Diseases (ICD-9-CM-A & ICD10-AM version 1), Diagnostic Related Groupings (DRGs[5]) and other lists of coded variables from the Data Dictionary for the NMDS. Such lists, including logical conjunctions of different sets of variables, are provided to exactly identify what is included (or excluded) in the english definition.
1 Background
Inheriting the Health Funding Authority purchasing processes, the Ministry currently purchases a range of inpatient events (principally Medical/Surgical events) from publicly funded hospitals via a casemix methodology know as the Weighted Inlier Equivalent Separations, Version 5 with Amendments for New Zealand (WIES5A). Casemix events are contracted for via Purchase Units (PUs) which are derived from a mapping of Health Service Speciality codes.
The introduction of ICD10-AM version 1 coding by Health and Hospital Services (HHS) required HHS’s to backmap their ICD10 coded data to ICD-9-CM-A in order to calculate DRG3.1’s for use in the WIES5A costweight calculation. In addition, the costweights themselves were beginning to date resulting in the funding of hospital services potentially diverging from their cost of production.
In order for casemix funding to remain relevant for service remuneration as well as reflecting the change in clinical coding which had occurred within the sector, the Health Funding Authority (HFA) and the Crown Health Association (CHA) established a Costweights Group dedicated to the generation of a new costweights schedule based on ICD-10-AM v2, AR-DRG 4.1, and Victoria's WIES8 costweights schedule. This paper builds on the work of the Costweights Group.[6]
2 Changes from the WIES5A version for the 2000/2001 FY
The main change from the 00/01 FY WIES5A methodology, which allows for blood and pre-admits, is the revision of costweights based on Victoria’s WIES8 system adapted to New Zealand circumstances. This revision involves updated costs from Victoria’s cost study used to generate WIES8, use of the New Zealand LOS profile, and allowance for blood and pre-admits. (see appendix attachment).
1 Propagation of the current exclusion framework
This document continues the framework developed last year, but updates that documentation for the introduction of WIES8A. Hence all existing exclusions from casemix remain.
It has been recommended that anaesthetic codes be captured on the NMDS and directly coded after the procedure code they relate to. The Coding Standards Advisory Committee and NCCH agreed to use as default anaesthetic codes GA -92502-02 or sedation 92503-00. This has implications for the exclusions defined in 3.2.13-3.2.20 which depend on either the second or third procedure code being blank. As a consequence, these tests have been augmented to test whether the second or third code is either blank or an anaesthetic code.
3 Areas for change in the future
A joint sector Costweights Project may continue to investigate casemix methodologies for the 2002/2003 FY, it is also possible that some minor changes will be required to the 01/02 WIES8A methodology, partly as additional variable and codes may be added to the NMDS.
1 Exclusion rule Post Natal Early Intervention
A new Health Speciality code to identify Post Natal Early Intervention cases has been approved by the National Data Policy Group (NDPG). The new health speciality code, P50, are excluded from casemix Purchase Unit allocation.
2 Neonatal CPAP
A field recording this variable has been introduced to the NMDS and HHSs are required to submit CPAP hours for neonates from 1 July 2001. For the 01/02 FY this field will not be used for calculations that make adjustments to the costweight for an event. It will, however, form the basis of a future study of CPAP utilisation and whether or not any supplementary payment is required for the use of CPAP for neonates. If yes, a decision will be made as to how this could best be applied, either by a modification to the WIES8A calculation or some other method. This work is in progress as part of the Maternity Casemix Review.
3 Other possible exclusions
Subject to changes on the NMDS, it may be possible to identify additional cases that require exclusion from casemix Purchase Unit allocation, e.g. CAPD & MUDS.
WIES8A calculation
The following section describes the derived variables required, the DRG reallocation tests applied (AR-DRG => WIES DRG), the Mechanical Ventilation calculation, the matching of events with appropriate costweights and the WIES8A case weight calculation. In what follows the phrases case weight and costweight may be used interchangeably.
1 Derived variables required in calculation
The following derived variables are used in the WIES8A calculation.
1 Length of Stay
The Length of Stay (LOS) calculation used in the methodology is specific for use within the WIES8A calculation. This is because it has a maximum and minimum applied to it, as well as having any Event Leave Days subtracted. A maximum of 365 days applies as the methodology is used for calculating the costweight associated with a particular year. A minimum of 1 day is applied to deal with the few cases where Event Leave Days are equal to the difference between the admission and discharge dates (Note: this does not affect the LOS comparison with low boundary points as the WIES DRG boundary points are integer and the tests for whether an event is same or one day use date tests rather than the LOS).
Hence, the calculated LOS equals the difference in integer days between the discharge and admission dates, minus any Event Leave Days. Further, this is set to 365 if the LOS is greater 365 or is set to 1 if the LOS=0.
2 Reallocated DRG
As in previous years a number of adjustments are to be made to the original AR-DRG 4.1 grouping by utilising the WIES DRG field, prior to the calculation of WIES8A. Some of the AN-DRG3 adjustments applied in earlier versions of WIES, namely Cerebral Infarction, Neonates, Transvascular Percutaneous Cardiac Intervention (Stents) and Chemotherapy, are no longer required as the modification has been included within AR-DRG 4.1. WIES DRGs are still required for Peritoneal Dialysis (an exclusion in New Zealand), Radiotherapy (in Victoria) and Bone Marrow Transplants.
Details of the DRG splits prior to the case weight calculation are given below. These events, however, should not have the original AR-DRG overwritten (Note: the MoH SAS code creates a new variable, DRG_NZ, to hold the WIES DRG appropriate for the case weight calculation). The WIES DRGs contain all the AR-DRGs as well as additional DRG codes (not used in AR-DRG) for the purpose of applying the appropriate costweights to NMDS events.
2 DRG Reallocations
The following are the tests for the allocation of AR-DRGs to WIES DRGs for the purposes of the WIES8A case weight calculation. Note that with the introduction of AR-DRG 4.1 and improvements in the coding system, Victoria now only uses two DRG splits.
1 AR-DRG A04, Bone Marrow Transplants
Bone Marrow Transplants have their AR-DRG 4.1 reallocated from A04Z to WIES DRG A04A if certain procedures were performed or to WIES DRG A04B if they were not. These are tested for by checking:
IF AR-DRG is equal to A04Z
AND
Any recorded procedure codes fall in the range:
ICD-10-AM 2nd Edition Bone Marrow, any procedure in the range (13706-00, 13706-06,13706-09,13706-10).
THEN
DRG is reallocated to WIES DRG A04A.
ELSE
IF AR-DRG is equal to A04Z
AND
No recorded procedure falls in the above range
THEN
DRG is reallocated to WIES DRG A04B.
NB: 13706-00 and 13706-09 map to the ICD-10-AM 1st edition procedure code 13706-00 and 13706-06 and 13706-10 map to the ICD-10-AM 1st edition procedure code 13706-06.
2 Adjustment for Peritoneal Dialysis
In recognition of cost differences between peritoneal and haemodialysis, episodes with a principal diagnosis of peritoneal dialysis (ICD-10-AM code Z49.2) are to be assigned a WIES DRG of L61Y. Note, however, that both dialysis DRGs are casemix exclusions in New Zealand; see 3.2.10 below.
3 Adjustment of medical AR-DRGs with radiotherapy[7]
Records with medical DRGs where radiotherapy (Z51.0) has been provided are mapped to AR-DRG R64Z (Radiotherapy). Medical DRGs are those where the number part of the DRG is greater than 60 (the format of a DRG is AnnA).
2.2.4 All other AR-DRGs
All other AR-DRGs not reallocated in the above tests are given the same DRG number, i.e. the WIES DRG is set to the same value as the AR-DRG.
3 Adjusted Mechanical Days
The WIES8A calculation includes a component for Adjusted Mechanical Ventilation Days used to calculate the MV copayment. However, not all events are eligible for this component and a range of DRGs have their days set to zero. Also, as the variable recording hours of mechanical ventilation was only introduced onto the NMDS from 1 July 1999, prior to this time procedures codes are tested as a proxy for calculating this component.
1 DRGs excluded from mechanical ventilation days
The following range of AR-DRGs have their event’s Adjusted Mechanical Ventilation Days set to zero and are ineligible for a MV copayment.
(A01Z, A02Z, A03Z, A04A, A04B, A05Z, A40Z, F02Z, F40Z, L61Y, P01Z, P02Z, P03Z, P04Z, P05Z, P60A, P60B, P61Z, P62Z, P63Z, P64Z, P65A, P65B, P65C, P65D, P66A, P66B, P66C, P66D, P67A, P67B, P67C, P67D, W01Z, 960Z, 961Z).
2 Calculation of mechanical ventilation days from hours
For other AR-DRGs than above, Adjusted Mechanical Ventilation Days is calculated in the following way:
If hours of ventilation are less than 6 then Adjusted Mechanical Ventilation Days is set to zero.
If hours of ventilation are 6 or more then Adjusted Mechanical Ventilation Days are calculated by adding 12 hours to the hours reported, dividing the result by 24 and rounding (i.e. gives integer days, effectively rounded up).
3 Calculation of mechanical ventilation days without hours
Prior to 1 July 1999 NMDS events did not have hours of mechanical ventilation reported (as this variable was only introduced from that date) and procedure tests are used to calculate Adjusted Mechanical Ventilation Days. These tests will still be required to calculate ventilation days for events prior to the 99/00 FY (but reported hours will be used, as above, for later events).
For included AR-DRGs (see 2.3.1), if any reported procedure falls in the range ICD9 (9672, 9671 or 9670) then the Adjusted Mechanical Ventilation Days is calculated to be, respectively, (5, 2 or 1). The days are set to zero if none of the above procedures is found. The ICD10 code equivalents are (1388202) => 5 days, (1388201 or 1385700 or 1387900) => 2 days and (1388200) => 1 day.
4 General Calculation
For the WIES8A calculation, each NMDS event is initially matched by its allocated WIES DRG to the file containing the WIES DRG costweights and other associated variables.
WIES DRGs are flagged as either Sameday, Oneday or other DRGs in this file by the SOflag (Same Day/One Day WIES DRG Flag) and each has some slightly different tests. The methodology is slightly different from what has been used in the last three years. While the development of the weight schedule has followed the same pattern as before, the calculation has now been presented in an easier format, using per diem rates for both high and low outliers, inlier weight, a one day weight, and a same day weight which is usually equal to half the one day weight.
The base WIES score for sameday episodes (inlier and low outlier), one day episodes (inlier and low outliers), and multiday inliers can be read directly from the WIES8 weights table using the appropriate column and row (WIES DRG4). The base WIES score for multiday low outliers can be calculated by multiplying the per diem weight given in the WIES8 weights table by the patient’s length of stay. The base WIES score for high outliers is obtained by multiplying the number of high outlier days by the high outlier per diem weight (from the WIES8 weights table and adding the multiday inlier weight (from table)). Technical details are provided in the following sections.
An event’s LOS is generally compared with the WIES DRG’s low and high LOS boundary points to determine an intermediate variable (IES) and which particular costweight should be applied to it. In the following sections, shortened variable names from the WIES DRG weights file are used (see also Appendix 4.1). Note that in the following table VIC-DRG4 is synonymous with DRG_NZ and WIES DRG.
|Variable |Label |Description |
|(Column Heading) | | |
|Victorian DRG |VIC-DRG4 |Victorian modification to AR-DRG4.1. |
|Same day medical target |Sdmt |VIC-DRG4s marked with a “Y” are classed as same day medical target VIC-DRG4s. VIC-DRG4s marked|
| | |with “N” are not classed as same day medical target VIC-DRG4s. WIES for same day patients |
| | |allocated to same day medical target VIC-DRG4s are calculated normally but the total WIES |
| | |associated with same day patients in these VIC-DRG4s cannot exceed specified levels (usually |
| | |6.5% of total WIES). Excess same day medical target WIES are not funded. |
|Mechanical ventilation |Mv_elig |This describes the way mechanical ventilation severity co-payments are made for the VIC-DRG4. |
| | |Options are :- |
| | |D: funded provided at least six hours of ventilation is provided. Patients attract a daily |
| | |rate of 0.7729 WIES |
| | |E: patients with a reported ICD-10-AM procedure code of 13382-02 are funded an additional |
| | |3.1323 WIES |
| | |4: funded for each day of mechanical ventilation after 4 days. Patients attract a daily rate |
| | |of 0.7729 WIES. |
| | |I: ineligible for mechanical ventilation co-payments |
|Other co-payments |Copay |Some groups of patients attract additional funds in recognition of their higher costs. Options|
|(Only in Victoria, not in New | |are:- |
|Zealand) | |Thal: a co-payment of 0.2648 WIES is made to patients with a reported ICD-10-AM thalessaemia |
| | |diagnosis code of D56.x or D57.2 (Note: These do not have to be principal diagnoses) |
|Low inlier boundary |Lb |The low length of stay boundary for inliers. Patients with a length of stay of less than the |
| | |low boundary are classed as low outliers. For most VIC-DRG4s the low boundary has been set at |
| | |a third of the estimated average length of stay for the VIC-DRG4. Boundaries are truncated to |
| | |the whole number. |
|High inlier boundary |Hb |The high length of stay boundary for inliers. Patients with a length of stay greater than the |
| | |high boundary are classed as high outliers. For most VIC-DRG4s the high boundary has been set |
| | |at three times the estimated average length of stay for the VIC-DRG4. Boundaries are rounded |
| | |to the nearest whole number. |
|Inlier average length of stay |i_alos |The average length of stay (days) for inliers. |
|VIC-DRG4 designation |Sd_od |Flag for designated sameday (S) or one day (O) VIC-DRG4s |
|Same day weight |Sd |The same day weight is used to allocate WIES to episodes where patients are admitted and |
| | |separated on the same day. Depending upon the VIC-DRG4, same day patients may be either low |
| | |outliers or inliers:- |
| | |Designated Same day VIC-DRG4s |
| | |The same day weight is based on the costs of same day patients. |
| | |Non-Same Day VIC-DRG4s with a low boundary of zero days |
| | |The same day weight is set at the multiday inlier weight. |
| | |Non-Same Day VIC-DRG4s with a low boundary of 1 day |
| | |The same day weight is set at half the multiday inlier weight |
| | |Non-Same Day VIC-DRG4s with a low boundary of 2 days or more (low outliers) |
| | |The same day weight is set at half of the multiday inlier weight divided by the low boundary |
| | |(0.5´md_in ¸ lb) |
|One day weight |Od |The one day weight is used to allocate WIES to episodes where patients have a length of stay |
| | |of one but who were not separated on the same day as they were admitted. Depending upon the |
| | |VIC-DRG4, one day patients may be either low outliers or inliers:- |
| | |Designated Same day VIC-DRG4s |
| | |The one day weight is based on the costs of all inliers excluding same day patients. If the |
| | |patient is an inlier they attract the full multiday inlier weight. If the patient is a low |
| | |outlier they attract the low outlier per diem weight. |
| | |Designated One day VIC-DRG4s |
| | |The one day weight is based on the costs of patients with a length of stay of one day. |
| | |Non-Same/One Day VIC-DRG4s with a low boundary of 1 day or less |
| | |The one day weight is set at the multiday inlier weight. |
| | |Non-Same/One Day VIC-DRG4s with a low boundary of 2 day or more (low outliers) |
| | |The one day weight is set at the low outlier per diem weight. |
|Low outlier multiday per diem |Lo_pd |The low outlier multiday per diem weight is used to allocate WIES to low outliers who have a |
|weight | |length of stay of at least two days. |
| | |Not all VIC-DRG4s have low outliers. No weight is reported in these cases. |
| | |For most VIC-DRG4s the weight is derived as: |
| | |md_in ¸ lb |
| | |The WIES value is calculated by multiplying the low outlier multiday per diem weight by the |
| | |patient’s length of stay. |
|Inlier multiday weight |md_in |The inlier multiday weight is used to allocate WIES to inliers who have a length of stay of at|
| | |least two days. |
| | |For designated VIC-DRG4s, same day/one day patients are excluded when deriving the inlier |
| | |multiday weight. |
1 Calculating WIES8A
To calculate the WIES weight allocated to a patient you need to:-
Calculate the WIES co-payment for MV(see box 1)
Calculate the base WIES allocation using the WIES DRG4 and the patient’s length of stay adjusted for mechanical ventilation per diem. This can be done using the appropriate weights from the WIES8A weights table.
Add the base WIES payment and co-payment (see box 3).
The steps are described in detail below with technical specifications provided in the boxes.
2 Copayment for Mechanical Ventilation
For 01/02 there is one co-payment, namely for mechanical ventilation. Technical specifications for mechanical ventilation co-payments are given in box 1.
To be eligible for a mechanical ventilation co-payment the patient must have had at least six hours of continuous mechanical ventilation and have been allocated to a WIES DRG4 that is eligible for a mechanical ventilation co-payment. WIES DRG4s are classed as either:
1. Eligible for daily co-payments of 0.7729 WIES (mv_elig =“D” in the WIES8A weights table);
2. Eligible for an episode WIES co-payment 3.1323 when the ICD-10-AM procedure code 13882-02 is present (mv_elig = “E” in the WIES8A weights table);
3. Eligible for daily co-payments at 0.7729 WIES for ventilated days in excess of four days (96 hours) mechanical ventilation (mv_elig = “4” in the WIES8A weights table); or
4. Ineligible for co-payments (mv_elig = “I” in the WIES8A weights table).
Box 1: Calculating Mechanical Ventilation Co-payments
Select mv_elig
case “D” then
if (hours on mechanical ventilation is greater than or equal to 6 )[8] then
Adjmvday = round((hours mechanical ventilation +12)/24)
else
adjmvday = 0
mv_copay = adjmvday ´ 0.7729
go to box 2b
case “E” then
adjmvday = 0
If any procedure of 13882-02
mv_copay = 3.1323
else
mv_copay = 0
go to box 2b
case “4” then
if (hours on mechanical ventilation > 96) then
adjmvday = round((hours mechanical ventilation +12)/24) - 4
else
adjmvday = 0
mv_copay = adjmvday ´ 0.7729
go to box 2b
otherwise do
adjmvday = 0
mv_copay = 0
go to box 2b
Base WIES payments for high outliers are reduced when a patient receives daily mechanical ventilation co-payments. To make this reduction you will need to remember the number of days receiving mechanical ventilation co-payments (“adjmvday” in the technical specifications).
In 99/00 Victoria provided a hip revision copayment, however, this is no longer required as these are separately identified in AR-DRG 4.1 (I03A, I03B).
3 Base WIES
To calculate a patient's base WIES you need to determine:
5. The patient’s WIES DRG4.
6. The patient’s length of stay (LOS).
7. The patient’s length of stay category (LOS_cat: “S”= same day, “O”= one day, “M”= multiday).
8. The number of mechanical ventilation co-payment days (“adjmvday” see box 2a).
9. The patient’s inlier status (“I”= inlier, “L”= low outlier, “H”= high outlier).
The patient’s length of stay and length of stay category are derived from the admission date, separation date and leave days. A maximum length of stay of one years (365 days) is used. This ensures that WIES are not allocated to extreme stays that are likely to represent non-acute care. Technical specifications are given in Box 2a.
Box 2a: Determining Length of Stay Category and Maximum Length of Stay
Sameday='Y' if admission date = separation date
Else sameday='N'
If (sameday = ‘Y’) then
LOS_cat = “S”
go to step/box 2b
else if (sameday = ‘N’) and (LOS less than or equal to 1[9]) then
LOS_cat = “O”
go to step/box 2b
else
LOS = min(LOS,365)
LOS_cat = “M“
go to step/box 2b
The patient’s inlier status is determined by comparing the patient’s length of stay with the inlier boundaries for the WIES DRG4 to which the patient is allocated. The low inlier and the high inlier boundaries are given in the WIES8A weights table.
A patient is classified as an inlier when their length of stay is greater than or equal to the low inlier boundary and less than or equal to the sum of the high inlier boundary plus any mechanical ventilation co-payment days.
Patients with a length of stay less than the low inlier boundary are classified as low outliers.
Patients with a length of stay greater than the sum of the high inlier boundary and mechanical ventilation co-payment days are classified as high outliers. Technical specifications are given in box 2b.
Box 2b: Calculate Inlier Status
If LOS < LB then
Inlier = “L”
go to box 2c
else if LOS > (HB + adjmvday) then
Inlier = “H”
go to box 2c
else
Inlier = “I”
go to box 2c
Separate columns occur in the WIES8A weights table for episodes which are
10. same day
11. one day
12. multiday low outliers
13. multiday inliers
14. high outliers.
The base WIES score for sameday episodes (inlier and low outlier), one day episodes (inlier and low outliers), and multiday inliers can be read directly from the WIES8A weights table using the appropriate column and row (WIES DRG4). The base WIES score for multiday low outliers can be calculated by multiplying the per diem weight given in the WIES8A weights table by the patient’s length of stay. The base WIES score for high outliers is obtained by multiplying the number of high outlier days by the high outlier per diem weight (from the WIES8A weights table and adding the multiday inlier weight (from table)). Technical details are provided in box 2c.
Box 2c: Calculate Base WIES
Select Inlier
case “L” do
select LOS_cat
case “S” do
base_WIES = sd
IES = base_WIES ¸ md_in
go to box 3
case “O” do
base_WIES = od
IES = base_WIES ¸ md_in
go to box 3
case “M” do
base_WIES = LOS ´ lo_pd
IES = base_WIES ¸ md_in
go to box 3
case “I” do
IES=1
select LOS_cat
case “S” do
base_WIES = sd
go to box 3
case “O” do
base_WIES = od
go to box 3
case “M” do
base_WIES = md_in
go to box 3
case “H” do
high_days = max(0, LOS - hb - adjmvday)
base_WIES = Md_in + high_days ´ ho_pd
IES = base_WIES ¸ Md_in
go to box 3
High outlier days are days stayed in excess of the high outlier boundary plus any mechanical co-payment ventilation days (“adjmvdays” - see boxes 1 and 2b).
Inlier Equivalent Separations (IES) can be calculated by dividing the base WIES by the multiday inlier weight.
4 Final WIES weight
The WIES score is calculated by adding the base WIES and the co-payment WIES. Details are provided in box 3.
Box 3: Calculating WIES Score
WIES8A = base_WIES + mv_copay
HFA Purchase Unit allocation
The following section describes the derived variables required, the exclusion tests applied and the mappings used to allocate MoH/DHB casemix Purchase Units to NMDS events.
1 Derived variables required in allocation
The following derived variables are required for casemix exclusion testing.
1 Patients Age
The patient’s age is calculated in integer years as at the date of discharge.
2 Length of Stay
(Note: same as section 2.1.1) The Length of Stay (LOS) calculation used in the methodology is specific for use within the WIES8A calculation. This is because it has a maximum and minimum applied to it, as well as having any Event Leave Days subtracted. A maximum of 365 days applies as the methodology is used for calculating the costweight associated with a particular year. A minimum of 1 day is applied to deal with the few cases where Event Leave Days are equal to the difference between the admission and discharge dates. (Note: this does not affect the LOS comparison with low boundary points as the DRG boundary points are integer and the tests for whether an event is same or one day use date tests rather than the LOS).
Hence, the calculated LOS equals the difference in integer days between the discharge and admission dates, minus any Event Leave Days. Further, this is set to 365 if the LOS is greater 365 or is set to 1 if the LOS=0.
2 Exclusions from casemix purchasing
The following section lists the tests that identify whether or not a particular event is purchased through the MoH casemix methodology. It should be noted that some of the tests are order sensitive, e.g. the Medical/Surgical test assumes that the Neonatal test has already been applied. Also, an event may be excluded for more than one reason (note - the MoH SAS methodology uses individual exclusion flag fields to generate an overall exclusion flag {Yes/No} for each event).
1 Neonatal Inpatient Casemix Purchasing
This test takes the form of an inclusion rule (as this is easier to specify than the converse exclusion rule). To be potentially included in neonatal casemix purchasing an event requires a Pregnancy & Childbirth Health Speciality code and to meet one of a variety of tests (originally agreed by the 98/99 joint HFA/HHS Maternity & Neonates project) which attempt to distinguish between well new-borns and those who required additional health services:
The Health Service Speciality code is in the Pregnancy & Childbirth range (i.e. where the first character is “P”)
AND
(The Health Service Speciality code is in the range (P40, P41, P42, P43)
OR
(The AR-DRG is in the range (P02Z, P61Z, P62Z, P03Z, P63Z, P64Z, P04Z, P65A, P65B, P65C, P65D, P05Z, P66A, P66B, P66C, P06A, P06B, P67B, P67A, P67C))
OR
(The AR-DRG is in the range (P60A, P01Z, P60B, P66D, P67D) AND (the third ICD diagnosis is NOT blank OR the first ICD procedure is NOT blank)))
2 Non- Medical/Surgical Purchasing
Events which have a DSS or Mental Health Service Speciality code, i.e. first character is “D” or “Y”, are excluded. In addition, Pregnancy & Childbirth events (where the first character is “P”) are excluded if they do not meet the criteria above in the Neonatal casemix inclusion rule.
3 Non Base Funding Purchases
Events which are not part of an HHS’s base contract purchasing are excluded. HFA base contract events, now base DHB service agreements, should have a Purchaser code in the range (01, 02, 03, 04, 13). Events with any other Purchaser code should be excluded, e.g. privates, ACC direct and Insurers, Elective, i.e. the former Waiting Times Fund (WTF), events, other MoH/DHB specific non-base purchasing, etc. In addition, any Admission Types of “ZW” (indicating an ACC elective purchase) are excluded.
4 Designated Hospital Purchasing
A combination of a range of Agencies and Facilities have been identified as the providers through which the MoH/DHBs will monitor base casemix contracts. All other facilities (historically designated as ‘rural’) are excluded. Note with HHS sub-contracting the list of included Facilities may require updating periodically (this assumes that the Agency will reflect the organisation who have the original contract with the HFA). A list of included Agencies and Facilities is given below. Any combination of Agency & Facility which does not fall in the below lists are excluded from MoH/DHB casemix purchasing.
|Health Agency code |Agency Name |
|1022 |Auckland Healthcare |
|3091 |Capital Coast Health |
|4121 |Canterbury Health |
|4111 |Coast Health Care |
|3082 |Good Health Wanganui |
|3061 |Hawke’s Bay Health |
|4131 |Healthcare Otago |
|4122 |Healthlink South |
|4123 |South Canterbury Health |
|3092 |Hutt Valley Health |
|2031 |Health Waikato |
|2042 |Lakeland |
|3081 |Midcentral Health |
|1011 |Northland Health |
|3101 |Nelson-Marlborough Health |
|2047 |Pacific Health |
|2041 |East Bay Health |
| |(kept for historical analysis) |
|2043 |Western Bay Health |
| |(kept for historical analysis) |
|1023 |South Auckland Health |
|4141 |Southern Health |
|2071 |Taranaki Healthcare |
|2051 |Tairawhiti Health |
|3093 |Wairarapa Health |
|1021 |Waitemata Health |
|0223 |Heart Surgery South Island |
| | |
| | |
|Facility code |Facility name |
|4111 |Whangarei Area Hospital |
|4112 |Kaitaia |
|3211 |Auckland |
|3212 |Greenlane |
|3213 |National Women’s |
|3214 |Middlemore |
|3215 |North Shore |
|3216 |Waitakere |
|3239 |Starship Hospital |
|5011 |Thames |
|3311 |Whakatane |
|4911 |Tauranga |
|3411 |Gisborne |
|5311 |Waikato |
|5312 |Rotorua |
|5313 |Te Kuiti |
|5320 |Queen Elizabeth |
|5323 |Tokoroa |
|4811 |Taumarunui |
|5329 |Taupo General |
|4711 |Taranaki Base |
|4712 |Hawera |
|3611 |Napier |
|3612 |Hastings Memorial |
|5711 |Wanganui |
|4311 |Palmerston North |
|5511 |Masterton |
|5812 |Hutt |
|5816 |Kenepuru |
|5811 |Wellington |
|3811 |Wairau |
|3911 |Nelson |
|4011 |Christchurch |
|4013 |Burwood |
|4014 |Christchurch Womens |
|3111 |Ashburton |
|5911 |Grey Base Hospital |
|4411 |Timaru |
|4211 |Dunedin |
|4511 |Southland |
|3250 |Manukau SuperClinic |
|3220 |Pukekohe |
|3221 |Papakura Obstetric |
|3240 |Botany Downs Maternity Hospital |
|4113 |Dargaville |
|4114 |Bay of Islands |
|8270 |Southern Cross, Hamilton |
|8331 |Bowen |
|8432 |Wakefield |
|8595 |Ascot Hospital |
|8233 |Mercy, Auckland |
|8422 |Our Lady’s Home of Compassion |
|8366 |St Georges |
|8377 |Southern Cross Trust, Christchurch |
|8580 |Oxford Day Clinic |
|3313 |Murupara |
|3314 |Opotiki |
|4212 |Wakari |
|8507 |Manor Park Hospital |
|8462 |Boulcott Clinic |
|8471 |Southern Cross, Wellington |
|5818 |Paraparaumu |
|5819 |Puketiro |
|5820 |Te Whare O Rangituhi |
|5814 |Porirua |
|8313 |Aorangi, (was Mercy) |
|8314 |Southern Cross, Palmerston North |
5 Non-Treated Patients
Events where no treatment is provided are excluded. These include Boarders who may be admitted or in the case of Cancelled Operations.
Boarders are tested for by checking the primary diagnosis code (only) for a set of codes:
ICD10 Boarders, primary diagnosis in the range:
Z763, Z764.
Cancelled Operations are tested for by checking that:
The primary operation/procedure code is blank
AND
That the event is non-acute (i.e. Admission Type not in “AC”,”ZC”)
AND
Length of Stay is less than 2 days
AND
The one (or more) of the first six diagnosis codes contain the following codes:
ICD10 Canc Ops, one (or more) of diagnosis 1-6 in the range:
Z530, Z531, Z532, Z538, Z539.
6 Error DRGs
Events coded to an Error AR-DRG are excluded. Error AR-DRGs are in the range (960Z, 961Z, 962Z, 963Z).
7 Some Transplants
Some organ Transplants are excluded as they are not purchased via casemix, e.g. liver, heart and lung transplants. Excluded Transplants are in the AR-DRG range (A01Z, A02Z, A03Z, A05Z). Simultaneous pancreas/kidney transplants will be coded so as to fall under A02Z, Multiple Organ Transplants, thus excluded from casemix purchasing.
8 Some Spinal Injuries
Some Spinal services are excluded as they are not purchased via casemix. Excluded Spinal services are in the Health Services Speciality code range (S50, S53).
9 Surgical Termination of Pregnancy
Surgical Termination of Pregnancy (ToP) events are excluded. These are tested for by checking:
The AR-DRG is equal to O40Z
AND
That the primary procedure/procedure codes fall in the range:
ICD10 Surg ToP, primary procedure in the range: (3564300, 3564301) AND primary diagnosis in the range (O040-O049 {O04*}).
10 Renal and Peritoneal Dialysis
The WIES DRGs for Renal Dialysis, L61Z, and Peritoneal Dialysis, L61Y, are excluded from casemix purchasing. Unless the associated events were previously coded to DRG3.1 572, this represents a new exclusion from casemix.
11 Sameday Chemotherapy & Radiotherapy
Some sameday cases for Chemotherapy and Radiotherapy are excluded from casemix purchasing.
These events are tested for by checking:
That the Admission date is the same as the Discharge date
AND
That either of the first two diagnosis codes fall in the range:
ICD10 Chem/Radio, either of the first two diagnosis in the range: (Z510, Z511, Z512).
12 Sleep Apnoea
Some Sleep Apnoea events where they stay overnight for tests are excluded from casemix purchasing. These events are tested for by checking:
That the integer difference in days between the Discharge and Admission dates is less than 2
AND
That the AR-DRG equals E63Z.
13 Lithotripsy
Some sameday Lithotripsy events are excluded from casemix purchasing. These events are tested for by checking:
That the Admission and Discharge dates are the same
AND
That the event is non-acute (i.e. Admission Type not in “AC”,”ZC”)
AND
That the primary procedure code falls in the following range:
ICD10 Lithotripsy, first procedure in the range: (3654600).
AND
That the second procedure code falls in the following range:
ICD10 Lithotripsy, second procedure in the range: (3654600,9250202,9250300, blank).
AND
That the third procedure code is in the range: (3654600,9250202,9250300, 9250202,9250300, blank).
14 Colposcopies
Some sameday Colposcopy events are excluded from casemix purchasing. These events are tested for by checking:
That the Admission and Discharge dates are the same
AND
That the event is non-acute (i.e. Admission Type not in “AC”,”ZC”)
AND
The patients age is greater than 15 years old
AND
That the primary procedure code falls in the following range:
ICD10 Colposcopy, first procedure in the range: (3560800, 3564600, 3564700, 3560801, 3553902, 3561100, 3553904, 3563705, 3553903, 3560802, 3561400).
AND
That the second procedure code falls in the following range:
ICD10 Colposcopy, second procedure in the range: (3560800, 3564600, 3564700, 3560801, 3553902, 3561100, 3553904, 3563705, 3553903, 3560802, 3561400,9250202,9250300, blank).
AND
That the third procedure code is in (9250202,9250300,blank).
15 Cystoscopies
Some sameday Cystoscopies events are excluded from casemix purchasing. These events are tested for by checking:
That the Admission and Discharge dates are the same
AND
That the event is non-acute (i.e. Admission Type not in “AC”,”ZC”)
AND
The patients age is greater than 15 years old
AND
That the primary procedure code falls in the following range:
ICD10 Cystoscopies, first procedure in the range: (3681201, 3681200, 3683600, 3683904, 3684503, 3683902, 3684501, 3684500, 3683900, 3684505, 3684504, 3684502, 3731801, 3731500, 3681501, 3682700).
AND
That the second procedure code falls in the following range:
ICD10 Cystoscopies, second procedure in the range: (3681201, 3681200, 3683600, 3683904, 3684503, 3683902, 3684501, 3684500, 3683900, 3684505, 3684504, 3684502, 3731801, 3731500, 3681501, 3682700, 9250202,9250300, blank).
AND
That the third procedure code is in (9250202,9250300,blank).
16 ERCPs
Some sameday ERCP (endoscopic retrograde cholangiopancreatography) events are excluded from casemix purchasing. These events are tested for by checking:
That the Admission and Discharge dates are the same
AND
That the event is non-acute (i.e. Admission Type not in “AC”,”ZC”)
AND
The patients age is greater than 15 years old
AND
That the primary procedure code falls in the following range:
ICD10 ERCP, first procedure in the range: (3048400, 3048401, 3048402, 3045200, 3048500, 3049100, 3045202, 3048501, 3049101, 3049400, 3045100, 3045201, 3044200).
AND
That the second procedure code falls in the following range:
ICD10 second procedure in the range: (3048400, 3048401, 3048402, 3045200, 3048500, 3049100, 3045202, 3048501, 3049101, 3049400, 3045100, 3045201, 3044200, 3047801, 3047802, 3209000, 3208400, 3209001, 3208401, 3209300, 3208700, 9030800, 3209400, 3207500, 3207200, 3207201, 3207501, 9031200, 9031201, 3207800, 3208100, 3209900, 3210800, 9034100, 3210500, 4181600, 3047303, 3047810, 4182500, 4182200, 3047304, 3047600, 3047601, 3047806, 3047809, 3047811, 3047812, 3047602, 3047813, 3047900, 3047807, 3047603, 3047300, 3047301, 3047500, 3047501, 3047803, 3209500, 3047804, 9250202,9250300, blank).
AND
That the third procedure code is in (9250202,9250300,blank).
17 Colonoscopies
Some sameday Colonoscopies events are excluded from casemix purchasing. These events are tested for by checking:
That the Admission and Discharge dates are the same
AND
That the event is non-acute (i.e. Admission Type not in “AC”,”ZC”)
AND
The patients age is greater than 15 years old
AND
That the primary procedure code falls in the following range:
ICD10 Colonoscopies, first procedure in the range: (3209000, 3208400, 3209001, 3208401, 3209300, 3208700, 9030800, 3209400, 3207500, 3207200, 3207201, 3207501, 9031200, 9031201, 3207800, 3208100, 3209900, 3210800, 9034100, 3210500).
AND
That the second procedure code falls in the following range:
ICD10 second procedure in the range: (3048400, 3048401, 3048402, 3045200, 3048500, 3049100, 3045202, 3048501, 3049101, 3049400, 3045100, 3045201, 3044200, 3047801, 3047802, 3209000, 3208400, 3209001, 3208401, 3209300, 3208700, 9030800, 3209400, 3207500, 3207200, 3207201, 3207501, 9031200, 9031201, 3207800, 3208100, 3209900, 3210800, 9034100, 3210500, 4181600, 3047303, 3047810, 4182500, 4182200, 3047304, 3047600, 3047601, 3047806, 3047809, 3047811, 3047812, 3047602, 3047813, 3047900, 3047807, 3047603, 3047300, 3047301, 3047500, 3047501, 3047803, 3209500, 3047804, 9250202,9250300, blank).
AND
That the third procedure code is in (9250202,9250300,blank).
18 Gastroscopies
Some sameday Gastroscopies events are excluded from casemix purchasing. These events are tested for by checking:
That the Admission and Discharge dates are the same
AND
That the event is non-acute (i.e. Admission Type not in “AC”,”ZC”)
AND
The patients age is greater than 15 years old
AND
That the primary procedure code falls in the following range:
ICD10 Gastroscopies, first procedure in the range: (4181600, 3047303, 3047810, 4182500, 4182200, 3047304, 3047600, 3047601, 3047806, 3047809, 3047811, 3047812, 3047602, 3047813, 3047900, 3047807, 3047603, 3047300, 3047301, 3047500, 3047501, 3047803, 3209500, 3047804, 3047801, 3047802).
AND
That the second procedure code falls in the following range:
ICD10 second procedure in the range: (3048400, 3048401, 3048402, 3045200, 3048500, 3049100, 3045202, 3048501, 3049101, 3049400, 3045100, 3045201, 3044200, 3047801, 3047802, 3209000, 3208400, 3209001, 3208401, 3209300, 3208700, 9030800, 3209400, 3207500, 3207200, 3207201, 3207501, 9031200, 9031201, 3207800, 3208100, 3209900, 3210800, 9034100, 3210500, 4181600, 3047303, 3047810, 4182500, 4182200, 3047304, 3047600, 3047601, 3047806, 3047809, 3047811, 3047812, 3047602, 3047813, 3047900, 3047807, 3047603, 3047300, 3047301, 3047500, 3047501, 3047803, 3209500, 3047804, 9250202,9250300, blank).
AND
That the third procedure code is in (9250202,9250300,blank).
19 Bronchoscopies
Some sameday Bronchoscopies events are excluded from casemix purchasing. These events are tested for by checking:
That the Admission and Discharge dates are the same
AND
That the event is non-acute (i.e. Admission Type not in “AC”,”ZC”)
AND
The patients age is greater than 15 years old
AND
That the primary procedure code falls in the following range:
ICD10 Bronchoscopies, first procedure in the range: (4188901, 4189800, 4188900, 4189200, 4189801, 4176404, 4176403, 4184600, 4184900, 4185500, 4189500).
AND
That the second procedure code falls in the following range:
ICD10 Bronchoscopies, second procedure in the range:. (4188901, 4189800, 4188900, 4189200, 4189801, 4176404, 4176403, 4184600, 4184900, 4185500, 4189500, 9250202, 9250300, blank).
AND
That the third procedure code is in (9250202,9250300,blank).
20 Day Case Blood Transfusions
Some sameday Blood Transfusion events are excluded from casemix purchasing. These events are tested for by checking:
That the Admission and Discharge dates are the same
AND
That the event is non-acute (i.e. Admission Type not in “AC”,”ZC”)
AND
That the primary diagnosis OR the first three procedure codes fall in the range:
ICD10 Blood, primary diagnosis in the range (Z513) OR {primary procedure in the range (9206000, 1370601, 1370602, 1370603) AND second procedure in the range (9206000, 1370601, 1370602, 1370603, blank) AND third procedure blank}.
3 Mapping of Health Service Speciality codes to MoH casemix PUs
MoH/DHB casemix Purchase Units are derived from a mapping of Health Service Speciality codes. This mapping only applies for included events, i.e. any events excluded from casemix purchasing should not be given a casemix PU code. (Note: the MoH SAS code gives excluded events a PU code of “EXCLU” rather than blank).
The following health service speciality codes are initially remapped to other health service speciality codes:
'M01' , 'M02' , 'M03' = 'M00'
'M06' , 'M07' = 'M05'
'M11' , 'M12' , 'M13' = 'M10'
'M16' , 'M17' , 'M18' , 'M19' = 'M15'
'M21' , 'M22' , 'M23' = 'M20'
'M26' , 'M27' , 'M28' = 'M25'
'M31' , 'M32' , 'M33' = 'M30'
'M36' , 'M37' , 'M38' = 'M35'
'M41' , 'M42' , 'M43' = 'M40'
'M46' , 'M47' , 'M48' = 'M45'
'M51' , 'M52' , 'M53' = 'M50'
'M56' , 'M57' , 'M58' = 'M55'
'M61' , 'M62' , 'M63' = 'M60'
'M66' , 'M67' , 'M68' = 'M65'
'M71' , 'M72' , 'M73' = 'M70'
'M76' , 'M77' , 'M78' = 'M75'
'M81' , 'M82' , 'M83' = 'M80'
'M87' , 'M88' = 'M85'
'M91' , 'M92' , 'M93' = 'M90'
'S01' , 'S02' , 'S03' = 'S00'
'S06' , 'S07' , 'S08' = 'S05'
'S11' , 'S12' , 'S13' = 'S10'
'S16' , 'S17' , 'S18' = 'S15'
'S21' , 'S22' , 'S23' = 'S20'
'S26' , 'S27' , 'S28' = 'S25'
'S31' , 'S32' , 'S33' = 'S30'
'S36' , 'S37' , 'S38' = 'S35'
'S41' , 'S42' , 'S43' = 'S40'
'S46' , 'S47' , 'S48' = 'S45'
'S51' , 'S52' , 'S53' = 'S50'
'S55' , 'S56' , 'S57' = 'S59'
'S61' , 'S62' , 'S63' = 'S60'
'S66' , 'S67' , 'S68' = 'S65'
'S71' , 'S72' , 'S73' = 'S70'
'S76' , 'S77' , 'S78' = 'S75'
And from there mapped to the following casemix purchased purchase units:
'S20' = 'D01.01'
'S50' = 'EXCLU'
'M00' , 'M05' , 'M08' , 'M85' , 'M86' , 'M89' = 'M00.01'
'M10' = 'M10.01'
'M14' = 'M10.05'
'M15' = 'M15.01'
'M20' = 'M20.01'
'M25' = 'M25.01'
'M30' = 'M30.01'
'M34' = 'M34.01'
'M40' , 'M75' = 'M40.01'
'M45' = 'M45.01'
'M49' = 'M49.01'
'M50' , 'M90' = 'M50.01'
'M54' , 'M94' = 'M54.01'
'M24' , 'M29' , 'M39' , 'M44' , 'M55' , 'M59' ,
'M64' , 'M69' , 'M74' , 'M79' , 'M84' = 'M55.01'
'M60' = 'M60.01'
'M65' = 'M65.01'
'M35' , 'M70' = 'M70.01'
'M80' = 'M80.01'
'S00' , 'S05' , 'S10' = 'S00.01'
'S15' , 'S19' = 'S15.01'
'S25' = 'S25.01'
'S30' = 'S30.01'
'S35' = 'S35.01'
'S40' = 'S40.01'
'S45' = 'S45.01'
'S58' , 'S59' = 'S55.01'
'S24', 'S60' , 'S65' = 'S60.01'
'S70' = 'S70.01'
'S75' = 'S75.01'
'P40' , 'P41' , 'P42' , 'P43' = 'W06.03'
other = 'EXCLU';
Each PU code is then described:
'D01.01'='Inpatient Dental treatment (DRGs)'
'M00.01'='General Internal Medical Services - Inpatient Services (DRGs)'
'M10.01'='Cardiology - Inpatient Services (DRGs)'
'M10.05'='Specialist Paediatric Cardiac - Inpatient Services (DRGs)'
'M15.01'='Dermatology - Inpatient Services (DRGs)'
'M20.01'='Endocrinology & Diabetic - Inpatient Services (DRGs)'
'M25.01'='Gastroenterology - Inpatient Services (DRGs)'
'M30.01'='Haematology - Inpatient Services (DRGs)'
'M34.01'='Specialist Paediatric Haematology - Inpatient Services (DRGs)'
'M40.01'='Infectious Diseases (incl Venereology) - Inpatient Services (DRGs)'
'M45.01'='Neurology - Inpatient Services (DRGs)'
'M49.01'='Specialist Paediatric Neurology Inpatient Services (DRGs)'
'M50.01'='Oncology - Inpatient Services (DRGs)'
'M54.01'='Specialist Paediatric Oncology - Inpatient Services (DRGs)'
'M55.01'='Paediatric Medical - Inpatient Services (DRGs)'
'M60.01'='Renal Medicine - Inpatient Services (DRGs)'
'M65.01'='Respiratory - Inpatient Services (DRGs)'
'M70.01'='Rheumatology (incl Immunology) - Inpatient Services (DRGs)'
'M80.01'='Palliative Care - Inpatient Services (DRGs)'
'S00.01'='General Surgery - Inpatient Services (DRGs)'
'S15.01'='Cardiothoracic - Inpatient Services (DRGs)'
'S25.01'='Ear, Nose and Throat - Inpatient Services (DRGs)'
'S30.01'='Gynaecology - Inpatient Services (DRGs)'
'S35.01'='Neurosurgery - Inpatient Services (DRGs)'
'S40.01'='Ophthalmology - Inpatient Services (DRGs)'
'S45.01'='Orthopaedics - Inpatient Services (DRGs)'
'S55.01'='Paediatric Surgical Services (DRGs)'
'S60.01'='Plastic & Burns - Inpatient Services (DRGs)'
'S70.01'='Urology - Inpatient Services (DRGs)'
'S75.01'='Vascular Surgery - Inpatient Services (DRGs)'
'W06.03'='Neonatal Inpatient (DRGs)'
other ='Not a DRG casemix Purchase Unit'
Appendices
1 Spreadsheet containing 01/02 FY DRG weights and associated variables for calculating WIES8A
Variables names translation 8 character to name:
SOflag {Same Day/One Day DRG Flag}
Sd {Same Day Costweight}
Od {One Day Costweight}
Md_in {Multi day inlier weight}
Ho_pd {High Outlier per diem}
Lb {Low Boundary Point for LOS}
Hb {High Boundary Point for LOS}
I_alos {Average Inlier LOS}
|NZ WIES 8 Schedule | | | | | | | | | | |
|Victorian DRG 4.1 | | |New Zealand Schedule Costweights | | | | |
| | | | | | | |Weights | | | |
|Victorian DRG 4.1 | | |New Zealand Schedule Costweights | | | | |
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|Victorian DRG 4.1 | | |New Zealand Schedule Costweights | | | | |
| | | | | | | |Weights | | | |
|Victorian DRG 4.1 | | |New Zealand Schedule Costweights | | | | |
| | | | | | | |Weights | | | |
|Victorian DRG 4.1 | | |New Zealand Schedule Costweights | | | | |
| | | | | | | |Weights | | | |
|Victorian DRG 4.1 | | |New Zealand Schedule Costweights | | | | |
| | | | | | | |Weights | | | |
|Victorian DRG 4.1 | | |New Zealand Schedule Costweights | | | | |
| | | | | | | |Weights | | | |
|Victorian DRG 4.1 | | |New Zealand Schedule Costweights | | | | |
| | | | | | | |Weights | | | |
|Victorian DRG 4.1 | | |New Zealand Schedule Costweights | | | | |
| | | | | | | |Weights | | | |
|Victorian DRG 4.1 | | |New Zealand Schedule Costweights | | | | |
| | | | | | | |Weights | | | |
|Victorian DRG 4.1 | | |New Zealand Schedule Costweights | | | | |
| | | | | | | |Weights | | | |
|Victorian DRG 4.1 | | |New Zealand Schedule Costweights | | | | |
| | | | | | | |Weights | | | |
|Victorian DRG 4.1 | | |New Zealand Schedule Costweights | | | | |
| | | | | | | |Weights | | | |
|Victorian DRG 4.1 | | |New Zealand Schedule Costweights | | | | |
| | | | | | | |Weights | | | |
|Victorian DRG 4.1 | | |New Zealand Schedule Costweights | | | | |
| | | | | | | |Weights | | | |
|Victorian DRG 4.1 | | |New Zealand Schedule Costweights | | | | |
| | | | | | | |Weights | | | |
|Victorian DRG 4.1 | | |New Zealand Schedule Costweights | | | | |
| | | | | | | |Weights | | | |
|Victorian DRG 4.1 | | |New Zealand Schedule Costweights | | | | |
| | | | | | | |Weights | | | |
|Victorian DRG 4.1 | | |New Zealand Schedule Costweights | | | | |
| | | | | | | |Weights | | | |
|Victorian DRG 4.1 | | |New Zealand Schedule Costweights | | | | |
| | | | | | |Weights | | | | | | | |Mech.Vent. |Same Day |Inlier Boundary |Average | |Outlier Per Diems | | | |Code |DRG Description |Copayment |One Day |Low |High |Inlier LOS |Inlier |High |Low |Same Day |One Day | |DRG41 | |mv_elig | |lb |HB |i_alos |md_in |ho_pd |lo_pd |sd |od | |Z60A |Rehabilitation W Catastrophic/Severe CC |D | |6 |16 |10.666667 |2.257240 |0.169293 |0.376207 |0.188103 |0.376207 | |Z60B |Rehabilitation no Catastrophic/Severe CC |D | |6 |14 |9.500000 |2.248247 |0.189326 |0.374708 |0.187354 |0.374708 | |Z60C |Rehabilitation, Sameday |D | |0 |3 |1.000000 |0.123319 |0.098655 |0.000000 |0.123319 |0.123319 | |Z61Z |Signs and Symptoms |D | |0 |7 |1.823607 |0.458610 |0.201188 |0.000000 |0.458610 |0.458610 | |Z62Z |F-Up After Completed Treat W/O Endoscopy |D | |0 |3 |1.016064 |0.340739 |0.268281 |0.000000 |0.340739 |0.340739 | |Z63A |Other Aftercare W Catastrophic/Severe CC |D | |2 |22 |7.663636 |1.282246 |0.167316 |0.641123 |0.320562 |0.641123 | |Z63B |Oth Aftercare W/O Catastrophic/Severe CC |D | |1 |10 |1.909621 |0.458957 |0.240339 |0.000000 |0.229479 |0.458957 | |Z64A |Other Factors Influenc Health Status >79 |D |Same day |2 |25 |10.121951 |1.458849 |0.115302 |0.729424 |0.338932 |0.729424 | |Z64B |Other Factors Influenc Health Status 15
and substr(adm_typ,2,1) ne 'C' then CYSTO='Y';
else CYSTO='N';
*BELOW IS EXCLUSION RULE FOR ERCPs;
if (put(op01, $ERCPa.)*put(op02, $op2test.))
and op03 in (' ','9250202','9250300')
and evendate=evstdate
and substr(adm_typ,2,1) ne 'C'
and age>15 then ERCP='Y';
else ERCP='N';
*BELOW IS EXCLUSION RULE FOR COLONOSCOPIES;
if (put(op01, $COLONsa.)*put(op02, $op2test.))
and op03 in (' ','9250202','9250300')
and evendate=evstdate
and substr(adm_typ,2,1) ne 'C'
and age>15 then COLON='Y';
else COLON='N';
*BELOW IS EXCLUSION RULE FOR GASTROSCOPIES;
if (put(op01, $GASTRa.)*put(op02, $op2test.))
and op03 in (' ','9250202','9250300')
and evendate=evstdate
and substr(adm_typ,2,1) ne 'C'
and age>15 then GASTRO='Y';
else GASTRO='N';
*BELOW IS EXCLUSION RULE FOR BRONCHOSCOPIES;
if (put(op01, $bron.)*((put(op02, $bron.) or op02 in (' ','9250202','9250300'))))
and op03 in (' ','9250202','9250300')
and evendate=evstdate
and substr(adm_typ,2,1) ne 'C'
and age>15 then BRONCHO='Y';
else BRONCHO='N';
*BELOW IS EXCLUSION RULE FOR DAY CASE BLOOD TRANSFUSIONS;
if (diag01='Z513' or (op01 in ('9206000','1370601','1370602','1370603') and
op02 in (' ','9206000','1370601','1370602','1370603') and
op03 =' '))
and evendate=evstdate
and substr(adm_typ,2,1) ne 'C' then TRANSFUS='Y';
else TRANSFUS='N';
*BELOW CREATES A MASTER EXCLUSION VARIABLE TO IDENTIFY ALL EXCLUDED EVENTS;
if NONMEDSG='Y' or Deshosp='N' or BOARDER='Y' or CANC_OP='Y' or ERR_DRG='Y'
or XPLANT='Y' or SPINAL='Y' or TERMPREG='Y' or RENAL='Y' or CHEM_RAD='Y' or SLEEP='Y' or LITHO='Y'
or COLPO='Y' or CYSTO='Y' or ERCP='Y' or COLON='Y' or GASTRO='Y' or BRONCHO='Y' or TRANSFUS='Y'
or base = 'N'
then EXCLU='Y';
else EXCLU='N';
*BELOW MAPS EVENTS TO CASEMIX PURCHASED UNITS OR IDENTIFIES AS CASEMIX EXCLUSIONS;
if EXCLU='N' then
do;
if NEONATE='Y' then PU='W06.03';
else pu = put(hlthspec, $newpu.);
end;
else PU='EXCLU';
PU_name=put(PU,$PU_name.);
*BELOW REALLOCATES BONE MARROW TRANSPLANT AN-DRGs;
if drg_nz='A04Z' then
do;
if (put(op01, $bone.) + put(op02, $bone.) + put(op03, $bone.) + put(op04, $bone.)+
put(op05, $bone.) + put(op06, $bone.) + put(op07, $bone.) + put(op08, $bone.)+
put(op09, $bone.) + put(op10, $bone.) + put(op11, $bone.) + put(op12, $bone.)+
put(op13, $bone.) + put(op14, $bone.) + put(op15, $bone.) )
then DRG_NZ='A04A';
else DRG_NZ='A04B';
end;
proc sort data = cwd.wies8; by vicdrg4;
data &outdset;
merge test (in=wanted)
cwd.wies8 (rename=(vicdrg4=drg_nz)
drop =vicdesc sameday);
by DRG_nz;
if wanted;
*------------------------------------------------------------------*;
*---------- Mechanical ventilation copayments first -----------*;
*------------------------------------------------------------------*;
if evendate < mdy(07,01,1999) then
do;
if drg_nz in ('A01Z', 'A02Z', 'A03Z', 'A04A', 'A04B', 'A05Z', 'A40Z', 'F02Z', 'F40Z', 'L61Y', 'P01Z', 'P02Z',
'P03Z', 'P04Z', 'P05Z', 'P60A', 'P60B', 'P61Z', 'P62Z', 'P63Z', 'P64Z', 'P65A', 'P65B', 'P65C',
'P65D', 'P66A', 'P66B', 'P66C', 'P66D', 'P67A', 'P67B', 'P67C', 'P67D', 'W01Z', '960Z', '961Z')
then adjmvday=0;
else if op01='1388202' or op02='1388202' or op03='1388202' or op04='1388202' or op05='1388202' or
op06='1388202' or op07='1388202' or op08='1388202' or op09='1388202' or op10='1388202' or
op11='1388202' or op12='1388202' or op13='1388202' or op14='1388202' or op15='1388202'
then adjmvday=5;
else if (put(op01, $mechven.) + put(op02, $mechven.) + put(op03, $mechven.) + put(op04, $mechven.)+
put(op05, $mechven.) + put(op06, $mechven.) + put(op07, $mechven.) + put(op08, $mechven.)+
put(op09, $mechven.) + put(op10, $mechven.) + put(op11, $mechven.) + put(op12, $mechven.)+
put(op13, $mechven.) + put(op14, $mechven.) + put(op15, $mechven.) )
then adjmvday=2;
else if op01='1388200' or op02='1388200' or op03='1388200' or op04='1388200' or op05='1388200' or
op06='1388200' or op07='1388200' or op08='1388200' or op09='1388200' or op10='1388200' or
op11='1388200' or op12='1388200' or op13='1388200' or op14='1388200' or op15='1388200'
then adjmvday=1;
else adjmvday=0;
end;
else
do;
if drg_nz in ('A01Z', 'A02Z', 'A03Z', 'A04A', 'A04B', 'A05Z', 'A40Z', 'F02Z', 'F40Z', 'L61Y', 'P01Z', 'P02Z',
'P03Z', 'P04Z', 'P05Z', 'P60A', 'P60B', 'P61Z', 'P62Z', 'P63Z', 'P64Z', 'P65A', 'P65B', 'P65C',
'P65D', 'P66A', 'P66B', 'P66C', 'P66D', 'P67A', 'P67B', 'P67C', 'P67D', 'W01Z', '960Z', '961Z')
then adjmvday=0;
else if (HMVHRS < 6) then adjmvday=0;
else adjmvday=round((HMVHRS+12)/24);
end;
*------------------------------------------------------------------*;
*---------- LOS category and Inlier category ---------*;
*------------------------------------------------------------------*;
if (sum(evendate, -evstdate, -(evntlvd/1)) lt lb) then inlier='L';
else if (sum(evendate, -evstdate, -(evntlvd/1)) gt sum(HB, adjmvday)) then inlier='H';
else inlier='I';
if evstdate=evendate then los_cat = 'S';
else if (sum(evendate, -evstdate, -(evntlvd/1)) less than or eq 1[10]) then los_cat = 'O';
else los_cat = 'M';
array px(15) op01-op15;
nmvsepn = 0;
select (mv_elig);
when ('D')
do;
if (adjmvday > 0) then mv_copay = adjmvday *0.7729;
else mv_copay = 0;
end;
when ('E')
do;
*--- Check for neonate mechanical ventilation ---*;
do i = 1 to 15;
if (substr(px(i),1,7) = '1388202') then nmvsepn = 1;
end;
if (nmvsepn = 1) then
do;
adjmvday= 0;
mv_copay = 3.1323;
end;
else
do;
adjmvday = 0;
mv_copay = 0;
end;
end;
when ('4')
if (hmvhrs gt 96) then
do;
adjmvday= sum(adjmvday, -4);
mv_copay = adjmvday *0.7729;
end;
else
do;
adjmvday = 0;
mv_copay = 0;
end;
otherwise
do;
adjmvday = 0;
mv_copay = 0;
end;
end;
*------------------------------------------------------------------*;
*---------- Box 3c: Calculate Base WIES -----*;
*------------------------------------------------------------------*;
select (Inlier);
when ('L')
do; *---- Same day cases --;
select (los_cat);
when ('S') wies8 = sd;
when ('O') wies8 = od;
when ('M') wies8 = los * lo_pd;
otherwise wies8 = 0;
end;
if md_in gt 0 then ies= wies8 / md_in;
else ies=0;
high_day = 0;
hiwies = 0;
end;
when ('I')
do; *---- Inlier calculations --;
select (los_cat);
when ('S') wies8 = sd;
when ('O') wies8 = od;
when ('M') wies8 = md_in;
otherwise wies8 = 0;
end;
ies= 1;
high_day=0;
hiwies = 0;
end;
when ('H')
do; *---- high outlier calculations --;
high_day = max(0,sum(los,-hb,-adjmvday));
hiwies = high_day * ho_pd ;
wies8 = md_in + hiwies;
if md_in gt 0 then ies= wies8 / md_in;
else ies=1;
end;
Otherwise
do;
high_day=0;
wies8=0;
ies=0;
end;
end;
*------------------------------------------------------------------*;
*---------- Box 5: Total WIES -----*;
*------------------------------------------------------------------*;
wies8 = sum(wies8, mv_copay);
*
* Clean up temporary datasets
*
*;
proc datasets library=work;
delete test;
run;
options mlogic mrecall details merror mprint symbolgen;
%mend w8ICD10;
-----------------------
[1] Senior Analyst, Decision Support, Capital and Coast DHB
[2] Project Analyst, Personal & Family Health Directorate – Service Development, Ministry of Health
[3] Senior Analyst, Hutt DHB
[4] Financial Years run from 1 July through to 30 June of the following calendar year and are abbreviated by stringing together the last two digits of the portions of calendar years in question, i.e. 98/99, 99/00, 00/01 represent the 3 consecutive financial years from 1 July 1998 through 30 June 2001.
[5] Two slightly different DRG versions are in use within the methodology. The DRG version currently in use within the NZ health sector is AR-DRG version 4.1 and all DRG tests on NMDS events refer to this version. However, for the purposes of applying costweights, some AR-DRGs are not clinically homogeneous and in these cases an AR-DRG may be reallocated to a different ‘WIES’ DRG. The WIES DRGs contain all the AR-DRGs as well as two additional DRG codes (not used in AR-DRG) for the purpose of applying the appropriate costweights to NMDS events.
[6] Costweights Project Group, , “National Service Framework Project: Report of the Costweights Project Group”, Ministry of Health, 23 March 2001 (available on Ministry of Health Website)
[7] This adjustment was added on 3 August 2001 by NZHIS. The adjustment was already in the SAS programme but had been omitted from this documentation.
[8] This was changed to greater than or equal to 6 on 1 October 2001.
[9] This was changed on 10 October 2001. It was less than one.
[10] This was changed on 10 October 2001 to be less than or eq 1, prior to that it was eq 1.
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