Global, regional, and national burden of subarachnoid hemorrhage among older adults, 1990-2021: a systematic analysis of prevalence, incidence, mortality, and DALYs with projections to 2050.

BACKGROUND: Subarachnoid hemorrhage (SAH) is an acute neurological disorder with high mortality and disability, particularly among older adults. Using data from Global Burden of Disease (GBD) 2021 study, we comprehensively assessed the global, regional, and national burden of SAH in older populations from 1990 to 2021 and projected future trends to 2050. METHODS: Data on SAH prevalence, incidence, mortality, and disability-adjusted life years (DALYs) were extracted for adults aged ≥ 60 years. Temporal trends were evaluated using estimated, annual, and average annual percentage changes (EAPC, APC, AAPC). Correlation, decomposition, frontier, predictive, and inequality, and risk factor analyses were applied to evaluate burden patterns. RESULTS: From 1990 to 2021, absolute prevalent and incident cases increased, whereas all age-standardized rates (ASRs) declined globally (EAPC < 0). The middle-socio-demographic index (SDI) region showed the greatest reduction, while Oceania had the highest age-standardized mortality (ASMR) and DALY (ASDR) rates. East Asia, particularly China, showed the steepest declines. SAH burden was concentrated in ages 60-75 group and higher in women; later cohorts exhibited lower risk. Population growth was the main driver of global increases in case and deaths, while epidemiological changes partially offset these increases and led to a net decline in DALYs. High systolic blood pressure remained the leading risk factor. Health inequalities widened, and frontier analysis revealed performance gaps among some high-SDI countries. Bayesian Age-Period-Cohort (BAPC) model projected rising absolute cases but continued declines in all ASRs by 2050. CONCLUSION: SAH burden among older adults shows regional, demographic, and developmental disparities. Despite progress, population aging demands sustained health-system strengthening to mitigate future burden.