Global, regional, and national burden of subarachnoid hemorrhage for adults aged 55 and older from 1990 to 2021, with projections of prevalence to 2050: an analysis for the Global Burden of Disease Study 2021

Objective: This study investigated temporal patterns in the global burden of subarachnoid hemorrhage (SAH) in individuals aged 55 years and older, aiming to inform future public health interventions. Methods: Using data from the 2021 Global Burden of Disease Study, which encompasses 204 countries and territories, this study examined the incidence, mortality, and disability-adjusted life years (DALYs) associated with SAH in those aged 55 and over. Age, sex, and sociodemographic index (SDI) quintiles were used to stratify the analyses. These analyses included Joinpoint regression to detect trend changes, frontier analysis to evaluate efficiency relative to development level, and ARIMA modeling to forecast future burden. Results: From 1990 to 2021, the global incidence of SAH among individuals aged 55 and above increased by 54.5%, rising from 228,299 to 352,609 cases. However, the age-standardized incidence rate (ASIR) declined by 32.5% (EAPC = -1.75). In contrast, the total number of deaths remained relatively stable, while the age-standardized mortality rate (ASMR) dropped by 57.2% (EAPC = -3.23). Although the total number of DALYs decreased only slightly, the age-standardized DALY rate (ASDR) fell by 23.7%, from 927.43 to 404.32 per 100,000 (EAPC = -3.12). Regionally, the burden was highest in medium and low–medium SDI areas, with ASIR, ASMR, and ASDR all peaking in medium SDI regions. Joinpoint analysis revealed that ASIR rose from 1990 to 1992, remained stable from 1993 to 1995, declined steadily from 1996 to 2013, and showed a slight upward trend from 2014 to 2021. Meanwhile, ASMR and ASDR consistently declined throughout the entire period. In 2021, the leading global risk factors for SAH-related DALYs and mortality were metabolic risks and hypertension, followed by behavioral risks, with varying contributions across SDI levels. Frontier analysis showed marked regional disparities in SAH control: some high SDI countries performed sub optimally, whereas many low SDI countries showed strong outcomes, underscoring both the potential for improvement and valuable lessons. ARIMA model projections suggest that over the next 29 years, the incidence and DALYs of SAH will continue to rise among those aged 55–69 years, while incidence in those over 70 may stabilize or decline, and overall mortality is expected to remain stable or decrease slightly. Conclusion: Although SAH incidence, mortality, and DALYs declined globally from 1990 to 2021, population aging drove a persistent increase in absolute case numbers, particularly in low- and middle-SDI regions. Projections suggest a growing disease burden among individuals aged 55–69, while mortality and disability risks remain significant in older age groups. Hypertension and metabolic abnormalities emerged as the primary modifiable risk factors, indicating the high preventability of SAH. To mitigate the global burden of SAH in aging populations, efforts should prioritize risk factor screening, healthcare capacity strengthening, rehabilitation system development, and international collaboration to facilitate tailored public health interventions.