Sex differences in carotid endarterectomy outcomes: results from the Ontario Carotid Endarterectomy Registry.BACKGROUND AND PURPOSE:  The existing literature provides conflicting evidence on surgical risks of carotid endarterectomy in women compared with men. We used data from a large population-based carotid surgery registry to determine whether sex differences exist in the risk of perioperative complications from carotid endarterectomy. METHODS:  We analyzed data from the Ontario Carotid Endarterectomy Registry, which contains data on all patients who underwent carotid endarterectomy in the province of Ontario between 1994 and 1997. We compared the risk of death or stroke at 30 days in women and men and used multivariate analyses to adjust for age, comorbid conditions, and surgical factors. Secondary analyses compared the risks of death and/or stroke in women and men at 2 years after surgery. RESULTS:  The study sample consisted of 6038 patients (35% women). The risks of perioperative stroke or death were not significantly different in women compared with men (adjusted hazard ratio, 1.10; 95% CI, 0.90 to 1.35). The combined risk of stroke or death at 2 years after surgery was also similar in women and men (adjusted hazard ratio, 1.05; 95% CI, 0.92 to 1.21). However, women were more likely to have a stroke (adjusted hazard ratio, 1.26; 95% CI, 1.05 to 1.51) and less likely to die (adjusted hazard ratio, 0.82; 95% CI, 0.68 to 0.99) within 2 years after surgery. CONCLUSIONS:  Perioperative complication rates from carotid endarterectomy are similar in women and men. Women should not be discouraged from carotid endarterectomy solely on the basis of surgical risks.