Operative mortality and procedure volume as predictors of subsequent hospital performance.

CONTEXT: Despite growing interest in evidence-based hospital referral for selected surgical procedures, there remains considerable debate about which measures should be used to identify high-quality providers.
OBJECTIVES: To assess the usefulness of historical mortality rates and procedure volume as predictors of subsequent hospital performance with different procedures. DESIGN, SETTING, AND PARTICIPANTS: Using data from the national Medicare population, we identified all U.S. hospitals performing one of 4 high-risk procedures between 1994 and 1997. Hospitals were ranked and grouped into quintiles according to 1) operative mortality (adjusted for patient characteristics) and 2) procedure volume. MAIN OUTCOME MEASURES: Risk-adjusted operative mortality in 1998 to 1999.
RESULTS: Although historical mortality and volume both predicted subsequent hospital performance, the predictive value of each varied by procedure. For coronary artery bypass graft surgery, mortality rates in 1998 to 1999 differed by 3.3% across quintiles of historical mortality (3.6% to 6.9%, best to worst quintile, respectively), but only by 1.0% across volume quintiles (4.8% to 5.8%). In contrast, for esophagectomy, mortality rates in 1998 to 1999 differed by 12.5% across volume quintiles (7.5% to 20.0%, best to worst quintile, respectively), but only by 1.5% across quintiles of historical mortality (11.4% to 12.9%). Historical mortality and procedure volume had comparable value as predictors of subsequent performance for pancreatic resection and elective abdominal aortic aneurysm repair. Our findings were similar when we repeated the analysis using data from later years.
CONCLUSIONS: Historical measures of operative mortality or procedure volume identify hospitals likely to have better outcomes in the future. The optimal measure for selecting high-quality providers depends on the procedure.