Assessing hospital performance for acute myocardial infarction: how should emergency department transfers be attributed.

BACKGROUND: The Centers for Medicare and Medicaid Services publicly reports risk-standardized mortality rates (RSMRs) to assess quality of care for hospitals that treat acute myocardial infarction patients, and the outcomes for inpatient transfers are attributed to transferring hospitals. However, emergency department (ED) transfers are currently ignored and therefore attributed to receiving hospitals. METHODS: New York State administrative data were used to develop a statistical model similar to the one used by Centers for Medicare and Medicaid Services to risk-adjust hospital 30-day mortality rates. RSMRs were calculated and outliers were identified when ED transfers were attributed to: (1) the transferring hospital and (2) the receiving hospital. Differences in hospital outlier status and RSMR tertile between the 2 attribution methods were noted for hospitals performing and not performing percutaneous coronary interventions (PCIs). RESULTS: Although both methods of attribution identified 3 high outlier non-PCI hospitals, only 2 of those hospitals were identified by both methods, and each method identified a different hospital as a third outlier. Also, when transfers were attributed to the referring hospital, 1 non-PCI hospital was identified as a low outlier, and no non-PCI hospitals were identified as a low outlier with the other attribution method. About one sixth of all hospitals changed their tertile status. Most PCI hospitals (89%) that changed status moved to a higher (worse RSMR) tertile, whereas the majority of non-PCI hospitals (68%) that changed status were moved to a lower (better) RSMR tertile when ED transfers were attributed to the referring hospital. CONCLUSIONS: Hospital quality assessments for acute myocardial infarction are affected by whether ED transfers are assigned to the transferring or receiving hospital. The pros and cons of this choice should be considered.