RELATIONSHIP BETWEEN PROVIDER VOLUME AND MORTALITY FOR CAROTID ENDARTERECTOMIES IN NEW-YORK-STATE

Background and Purpose-The objective of this study was to assess the r elationship between each of 2 provider volume measures for carotid end arterectomies (CEs) (annual hospital volume and annual surgeon volume) and in-hospital mortality. New York's Statewide Planning and Research (SPARCS) administrative database was used to identify all 28207 patie nts for whom carotid endarterectomy was the principal procedure perfor med in New York State hospitals between January 1, 1990, and December 31, 1995. Methods-A statistical model was developed to predict in-hosp ital mortality using age, admission status, and several conditions fou nd to be associated with higher-than-average mortality. This model was then used to calculate risk-adjusted mortality rates for various inte rsections of hospital and surgeon volume ranges. Results-Risk-adjusted in-hospital mortality ranged from 1.96% (95%confidence interval, 1.47 to 2.57) for patients having surgeons with annual CE volumes of <5 in hospitals with annual CE volumes of less than or equal to 100 to 0.94 % (95% confidence interval, 0.73 to 1.19) for patients having surgeons with annual volumes of greater than or equal to 5 in hospitals with a nnual CE volumes of >100. These 2 rates were statistically different. Conclusions-We conclude that the in-hospital mortality rates for carot id endarterectomies performed by surgeons with extremely low annual vo lumes (<5) and for hospitals with low volumes (less than or equal to 1 00) are significantly higher than the in-hospital rates of higher-volu me surgeons and hospitals, even after taking preprocedural patient sev erity of illness into account.