Risk of surgery and anesthesia for ischemic stroke

Background: The goal of this study was to determine if the combination of s urgery and anesthesia is an independent risk factor for the development of incident (first-time) ischemic stroke. Methods: All residents of Rochester, MN, with incident ischemic stroke from 1960 through 1984 (1,455 cases and 1,455 age-and gender-matched controls) were used to identify risk factors associated with ischemic stroke. Cases a nd controls undergoing surgery involving general anesthesia or central neur oaxis blockade before their stroke/index date of diagnosis were identified. A conditional logistic regression model was used to estimate the odds rati o of surgery and anesthesia for ischemic stroke while adjusting for other k nown risk factors. Results: There were 59 cases and 17 controls having surgery within 30 days before their stroke/index date. After adjusting for previously identified r isk factors, surgery within 30 days before the stroke/index date (periopera tive period) was found to be an independent risk factor for stroke (P < 0.0 01; odds ratio, 3.9; 95% confidence interval, 2.1-7.4). In an analysis that excluded matched pairs where the case and/or control under-went surgery co nsidered "high risk" for stroke (cardiac, neurologic, or vascular procedure s), "non-high-risk surgery" was also found to be an independent risk factor for perioperative stroke (P = 0.002; odds ratio, 2.9; 95% confidence inter val, 1,5-5,7). Conclusion: Our results suggest that there is an increased risk of ischemic stroke in the 30 days after surgery and anesthesia. This risk remains elev ated even after excluding surgeries (cardiac, neurologic, and vascular surg eries) considered to be high risk for ischemic stroke.