Increased body mass index associated with reduced risk of delayed cerebral ischemia and subsequent infarction after aneurysmal subarachnoid hemorrhage

Background: Increased body mass index (BMI) may be protective against cerebral ischemia in certain clinical contexts. Objective: To investigate whether increased BMI was associated with delayed cerebral ischemia (DCI) and subsequent infarction after aneurysmal subarachnoid hemorrhage (aSAH). Methods: We retrospectively reviewed the clinical course of patients presenting to our institution for management of aSAH. Patientwere segregated according to BMI<or≥29.4, a value determined by Classification and Regression Tree analysis. Predictors of DCI and delayed infarction were identified using stepwise multivariate logistic regression analysis. Results: There were 161 patients included for analysis. Average BMI within our patient cohort was 28.9, with 67 patients presenting with a BMI of ≥29.4 on admission. DCI occurred in 50 patients (31.1%) and was complicated by delayed infarction in 15 patients (9.3%). On stepwise multivariate analysis, BMI ≥ 29.4 was independently associated with reduced likelihood of DCI (odds ratio [OR] 0.42, 95% confidence interval [CI] 0.18-0.92) and delayed infarction (OR 0.13, 95% CI 0.02-0.61; P = .008). Increasing maximum flow velocity on transcranial Doppler ultrasound was independently associated with increased odds of both DCI (Unit OR 1.19, 95% CI 1.09-1.30; P < .001) and delayed infarction (Unit OR 1.31, 95% CI 1.13-1.56; P < .001), while intracerebral hemorrhage was independently associated with increased odds of delayed infarction (OR 6.99, 95% CI 1.82-30.25; P = .005). Conclusion: We report an association between elevated BMI and reduced incidence of DCI and delayed infarction, suggesting a protective effect of increasing BMI on the risk of ischemic complications after aSAH.