1. 1 WIES Estimation Raymond Robbins

2. 2 WIES Estimation Objective Estimate WIES for uncoded episodes — Separated episodes — Current inpatients (WIP WIES) Why? — Used by finance — Used by Acute Operations management

3. 3 WIES Estimation Strategy Partition episodes into groups — 1 Renal dialysis — 2 Liver transplant — 5 Elective surgery * — 6 ED non-admitted — 7 Day oncology — 8 Other one day — 9 Other same day — 11 Other multiday * Fit a statistical model to each group based on historical data

4. 4 WIES Estimation Strategy – Known DRG For some groups we “know” the DRG based on separation Unit — 1 Renal dialysis – L61Z — 2 Liver transplant – A01Z Simply calculate the WIES based on length of stay (using ICU hours x factor to estimate MV hours for Liver transplant patients)

5. 5 WIES Estimation Strategy – Unknown DRG For other groups fit a Generalised Linear Model (GLM) using information we have — 5 Elective surgery * — 6 ED non-admitted — 7 Day oncology — 8 Other one day — 9 Other same day — 11 Other multiday * A GLM model combines — Linear regression model for continuous factors — Analysis of variance for discrete factors

6. 6 WIES Estimation Factors Used in the Models Continuous Factors Length of stay ICU hours Theatre minutes ED hours Discrete Factors Admission source Discharge destination Unit Ward ED triage category Age group (not age) Elective surgery PPP Length of stay type Financial group Each model uses only a subset of these factors!

7. 7 WIES Estimation Fitting the Models The models are fitted to historical data using a statistics package — Minitab — SAS — Stata Model coefficients are stored in tables in SQL database and used to predict WIES for new uncoded episodes

8. 8 WIES Estimation How good are the predictions? Column Labels Row LabelsJan-12Feb-12Mar-12Apr-12May-12Jun-12Jul-12Aug-12Sep-12 05 - Elective episodes Sum of wies_actual95016211821145717431600163217191111 Sum of wies_est95916191750144617171613158216741057 Sum of abs_error10-3-72-11-2613-50-45-54 06 - ED non-admitted Sum of wies_actual388366377370377406150164124 Sum of wies_est385368374378 409149165121 Sum of abs_error-41-38132-3 08 - Other oneday Sum of wies_actual199167215187186194161146132 Sum of wies_est191161214185193206170169134 Sum of abs_error-8-60-26129232 09 - Other sameday Sum of wies_actual188192201192217198199202136 Sum of wies_est200201220192227200205216147 Sum of abs_error12919010261411 11 - Other multi-day Sum of wies_actual267030953553327134633376310134102042 Sum of wies_est273331003457320634993362319834622085 Sum of abs_error625-96-6536-14975242 Total Sum of wies_actual470857856506579563416166563362514050 Total Sum of wies_est479657826352572563736183569662944051 Total Sum of abs_error88-3-153-70321763430

9. 9 WIES Estimation WIES work in progress estimates

10. 10 WIES Estimation Improvements Estimate DRG Shorten coding timeframe Mode needs to be regularly “re-taught”