Abstract Number: Esoc2026a1528 Incidence of Aneurysmal Subarachnoid Hemorrhage by Age, Sex, Region, and Time Period in Kazakhstan: A National Cohort Study

Abstract Background and aims Aneurysmal subarachnoid hemorrhage (aSAH) accounts for approximately 5% of all strokes and is associated with high morbidity and mortality. The global crude incidence is estimated at 7.9 per 100,000 person-years. Despite a worldwide decline in incidence, substantial regional variation persists, and data from Central Asia remain scarce. This study aimed to estimate the incidence of aSAH in Kazakhstan by region, age, sex, and time period. Methods National inpatient data on hospital admissions for aSAH from 698 medical institutions across Kazakhstan were analyzed (2014-2024). Crude incidence rates were calculated per 100,000 person-years. Age- and sex-standardized incidence rates were calculated by direct standardization to the age- and sex-specific population structure of Kazakhstan (2014-2024). Associations with age, sex, calendar year, and region were assessed using Poisson regression with log-population as an offset, and results were reported as incidence rate ratios (IRR) with 95% confidence intervals. Results The overall crude incidence of aSAH was 6.0 per 100,000 person-years (95% CI 5.8-6.2). Incidence increased with age, peaking in people aged 71-80 years (IRR 1.59; 95% CI 1.37-1.86, vs. 51-60 years). Male sex was associated with a higher incidence compared with females (IRR 1.13; 95% CI 1.02-1.25). A significant decreasing temporal trend was observed, corresponding to an average annual reduction of approximately 10% (IRR per year 0.90; 95% CI 0.88-0.92). Substantial regional heterogeneity persisted after adjustment. The overall age- and sex-standardized incidence was 6.7 per 100,000 person-years (95% CI 6.4-6.9). Conclusions aSAH incidence in Kazakhstan demonstrates pronounced age dependence, male predominance, significant regional variation, and a declining temporal trend. Conflict of interest Karashash Menlibayeva: nothing to disclose.