Background-Except in cardiac surgery, measuring quality with procedure-specific mortality rates is unreliable due to small sample sizes at individual hospitals. Statistical power can be improved by combining mortality data from multiple operations. We sought to determine whether this approach would still be useful in understanding performance with individual procedures.Methods-We studied eleven high-risk operations performed in the national Medicare population (1996)(1997)(1998)(1999). For each operation, we calculated 1) the risk-adjusted mortality rate for the procedure and 2) the mortality rate with up to ten other operations combined ("other" mortality). To test for an association between these mortality rates, we calculated the correlation coefficient adjusting for random variation. We then collapsed hospitals into quintiles of other mortality and calculated procedure-specific mortality rates within each of these quintiles.Results-Mortality with specific operations was modestly correlated with other mortality: coefficients ranged from 0.14 for pneumonectomy to 0.35 for esophagectomy. Despite small to moderate correlations, other mortality was a good predictor of procedure-specific mortality for 10 of the 11 operations. Pancreatic resection had the strongest relationship, with procedure-specific mortality rates at hospitals in the worst quintile of other mortality 3-fold higher than those in the best quintile (15.2% vs. 6.3%, p<.001). Pneumonectomy had the weakest relationship, with no significant relationship between other mortality and procedure-specific mortality.Conclusions-Hospitals with low mortality rates for one operation tend to have lower mortality rates for other operations. These relationships suggest that different operations share important structures and processes of care related to performance. Future efforts aimed at predicting procedurespecific performance should consider incorporating data from other operations at that hospital.
KeywordsMeasurement; surgery; quality; performance; hospitals
IntroductionBecause of widespread recognition that surgical quality varies widely, there is growing demand from patients, providers, and payers for better measures of surgical outcomes (1,2). Riskadjusted mortality rates are a simple and reliable measure of surgical quality and have been used to good effect in cardiac surgery (3,4 frequently enough to reliably discriminate quality among individual hospitals using this approach (5,6).One way to improve outcomes measurement in non-cardiac surgery is to combine several operations together when assessing hospital mortality rates (7). However, this approach will only be useful to the extent that hospital performance with different operations is correlatedi.e., that hospitals good at one operation are also good at others. While previous studies show relatively weak relationships between outcomes for different medical diagnoses, there is some reason to believe these relationships may be stronger in surgery (8,9). Many high-risk operations are dependent ...