1. Rhine-Westhalia Institute for Economic Research in Germany 1 “Peak demand in hospitals and patient outcomes” Christoph Schwierz, RWI Essen Boris Augurzky, RWI Essen, IZA Bonn Axel Focke, University Duisburg-Essen Jürgen Wasem, University Duisburg-Essen

2. Rhine-Westhalia Institute for Economic Research in Germany 2 Research question Sudden surge in demand Quality of treatment of hospital-in-patients? Rationale High variation in daily patient volume Legal requirements for staff-to-patient ratios? Introduction

3. Rhine-Westhalia Institute for Economic Research in Germany 3 Literature review Comparing patient outcomes across hospitals Unobservable hospital differences Unobservable selection of patients Comparing patient outcomes within hospitals Unobservable selection of patients

4. Rhine-Westhalia Institute for Economic Research in Germany 4 Issues Data and samples Key variables: Patient outcomes, demand, selection Estimation strategies

5. Rhine-Westhalia Institute for Economic Research in Germany 5 Data Hospital discharge data 730.000 patient cases From 430 medical departments within 72 acute- care German hospitals Patient characteristics: –Age, sex, insurance type Several risk-adjusters: –4-digit diagnosis, patient clinical complexity level, relative diagnosis weight, etc.

6. Rhine-Westhalia Institute for Economic Research in Germany 6 Samples Admission \ Risk type LowHigh Elective Elective low-risk Elective high-risk Emergency Emergency low-risk Emergency high-risk

7. Rhine-Westhalia Institute for Economic Research in Germany 7 Patient outcomes Excess length of stay In-hospital mortality Died within 1 day after admission Died within hospital stay Emergency readmission Readmitted as an emergency case within 15 days after last discharge

8. Rhine-Westhalia Institute for Economic Research in Germany 8 Key variables: Unexpected Demand Variation Deviation of actual from predicted patient count Result 89% of variation in patient volume is predictable

9. Rhine-Westhalia Institute for Economic Research in Germany 9 Key variables: Unobservable selection Excess share of admissions (Dobkin 2003) Excess weekend mortality due to higher unobservable frailty of patients admitted on weekends With selection index excess mortality on weekends disappears

10. Rhine-Westhalia Institute for Economic Research in Germany 10 Descriptive Statistics Patient characteristics and outcomes by sample

11. Rhine-Westhalia Institute for Economic Research in Germany 11 Dependent variables: Excess length of stay Probability of in-hospital death Probability of the occurrence of an emergency readmission Explanatory variables Unexpected demand variation Index of unobservable selection Risk-adjusters Models estimated in 128 specifications Estimation strategy Multivariate econometric methods

12. Rhine-Westhalia Institute for Economic Research in Germany 12 Length of stay increases with unexpected demand for emergency and decreases for elective admissions Unexpected Demand in Percentiles Excess Length of Stay Elective low-risk Elective high-risk Emergency low-risk Emergency high-risk

13. Rhine-Westhalia Institute for Economic Research in Germany 13 Length of stay increases with excess admission ratio Unobservable Selection in Percentiles Excess Length of Stay Elective low-risk Elective high-risk Emergency low-risk Emergency high-risk

14. Rhine-Westhalia Institute for Economic Research in Germany 14 After selection correction no significant impact of demand on 1 day mortality High-risk emergency sample Without selection index With selection index

15. Rhine-Westhalia Institute for Economic Research in Germany 15 Summary of results Patient outcome Significant impact of demand Significant impact of unobservable selection Length of stayYes In-hospital mortality NoYes Emergency readmission NoYes

16. Rhine-Westhalia Institute for Economic Research in Germany 16 Conclusion Unobservable selection of patients is an issue also in within-hospital studies Ignoring selection can give misleading results Overall, hospitals do seem to deal well with variation in demand