Sex disparities in case fatality rate after aneurysmal subarachnoid haemorrhage: a prospective longitudinal...

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 haemorrhage (aSAH) remain conflicting. We aimed to investigate sex differences in 90-day CFR post-aSAH and identify explanatory factors.

The UK Biobank is a prospective population-based cohort study, including 502,411 participants, with baseline assessments between 2006 and 2010. Participants who developed aSAH during follow-up were identified through linkage with hospitalisation records and national death registries. Primary outcome was 90-day CFR post-aSAH. Kaplan-Meier survival analysis and multivariable Cox proportional hazard regression assessed sex disparities in CFR and potential explanatory factors.

We included 990 participants with aSAH, 634 (64.0%) females (age 66.0 ± 8.4) and 356 males (36.0%) (65.1 ± 8.6). At 90 days, 214 of 634 females (33.8%) and 98 of 356 males (27.5%) had died (OR 1.34; 95% CI, 1.01-1.78). Survival analysis demonstrated a sex difference in 90-day CFR (log-rank P = .046) with early divergence and consistently lower survival probability in females. After adjusting for age and covariates that varied by sex at baseline and at time of aSAH, hazard ratio (HR) for case fatality in females was 1.15 (95% CI, 0.90-1.49). In sex-specific multivariable models, HRs for case fatality for age were 1.04 (95% CI, 1.02-1.06) in females and 1.04 (95% CI, 1.01-1.07) in males; for anti-hypertensives use 1.76 (95% CI, 1.23-2.51) and 1.98 (95% CI, 1.23-3.17); and for current smoking 1.87 (95% CI, 1.31-2.67) and 1.64 (95% CI, 0.95-2.82).

Females had a higher unadjusted 90-day CFR post-aSAH. This sex difference is partially explained by higher age at aSAH and differences in modifiable baseline risk factors such as hypertension and smoking.