Abstract DP323: Sex Disparities in Case Fatality Rate After Aneurysmal Subarachnoid Hemorrhage: <i>A Prospective Longitudinal Population-Based Cohort Study</i>

Introduction: While increased female susceptibility to intracranial aneurysm development and rupture is well-known, data on sex differences in case fatality rates (CFR) after aneurysmal subarachnoid hemorrhage (aSAH) remain conflicting. In this population-based study, we investigated sex differences in 90-day CFR after aSAH and aimed to identify explanatory factors. Methods: The UK Biobank is a prospective population-based cohort study including 502,411 participants, aged 40-70 years, with baseline assessments between 2006 and 2010. All participants who developed aSAH during follow-up were identified through linkage with hospitalization records and national death registers. The primary outcome was 90-day CFR after aSAH. Kaplan-Meier survival analysis and multivariate Cox proportional hazard regression analysis were used to assess sex differences in CFR and identify potential explanatory factors. Results: We included 990 participants with aSAH, of whom 634 (64.0%) were females (mean age 66.0±8.4) and 356 were males (36.0%) (mean age 65.1±8.6). At 90 days, 214/634 females (33.8%) and 98/356 males (27.5%) had died (OR 1.34; 95%-CI:1.01-1.78). Survival analysis demonstrated a difference in 90-day CFR between both sexes (log-rank p=0.046) with an early divergence and consistently lower survival probability in females. (Figure) After adjusting for age and covariates that varied by sex at baseline and time of aSAH (smoking status, alcohol use, diabetes, use of anti-hypertensives, cholesterol-lowering medication and socio-economic status), the hazard ratio (HR) for case fatality in females was 1.15 (95%-CI:0.90-1.49). In sex-specific multivariate models, HRs for case fatality were for age in females 1.04 (95%-CI:1.02-1.06) and males 1.04 (95%-CI:1.01-1.07), and for use of anti-hypertensives in females 1.76 (95%-CI:1.23-2.51 and males 1.98 (95%-CI:1.23-3.17). Conclusions and Relevance: Females had a higher 90-day CFR after aSAH than males, and this difference is in part explained by the higher age and lower socio-economic status in females. Future studies should investigate treatment- and complication-related contributors to sex disparities in aSAH outcomes.