Background and Purpose-Because there is considerable variation in practice patterns and outcomes for carotid endarterectomy (CE), there is a need to study the processes of care that are associated with adverse outcomes. The purpose of this study was to examine the impact of processes of care and surgical specialty on adverse outcomes for CE. Methods-A retrospective cohort study based on a voluntary CE registry containing 3644 patients undergoing CE between April 1, 1997, and March 31, 1999, in New York hospitals was used in the study. A multivariable statistical model was used to identify significant independent patient risk factors and to examine the association of processes of care and surgical specialty with outcomes after adjustment for differences in patient risk factors. Results-The overall adverse outcome (in-hospital death or stroke) rate was 1.84%. After adjustment for differences in 7 patient risk factors that were significantly related to adverse outcomes, the use of Ն1 specific processes of care (eversion endarterectomy, protamine, or shunts) was found to be associated with lower odds of an adverse outcome relative to patients undergoing CE without the processes (ORϭ0. 42, Pϭ0.006). Similarly, patients undergoing surgery performed by vascular surgeons had lower odds of experiencing an adverse outcome (ORϭ0.36, Pϭ0.009). Processes of care and surgical specialty were highly correlated with one another. Conclusions-Processes of care and surgical specialty are significant interrelated determinants of adverse outcome for CE.

Background and Purpose-The objective of this study was to assess the relationship between each of 2 provider volume measures for carotid endarterectomies (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 28 207 patients for whom carotid endarterectomy was the principal procedure performed in New York State hospitals between January 1, 1990, and December 31, 1995. Methods-A statistical model was developed to predict in-hospital mortality using age, admission status, and several conditions found to be associated with higher-than-average mortality. This model was then used to calculate risk-adjusted mortality rates for various intersections 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 Ͻ5 in hospitals with annual CE volumes of Յ100 to 0.94% (95% confidence interval, 0.73 to 1.19) for patients having surgeons with annual volumes of Ն5 in hospitals with annual CE volumes of Ͼ100. These 2 rates were statistically different. Conclusions-We conclude that the in-hospital mortality rates for carotid endarterectomies performed by surgeons with extremely low annual volumes (Ͻ5) and for hospitals with low volumes (Յ100) are significantly higher than the in-hospital rates of higher-volume surgeons and hospitals, even after taking preprocedural patient severity of illness into account. (Stroke. 1998;29:2292-2297.)