Divergent trajectories of inflammatory bowel disease in East, South, South-East and Central Asia: A comprehensive GBD 2021 analysis

Background: Inflammatory bowel disease (IBD) is no longer confined to Western populations; its burden is rising across Asia, a region with marked demographic, economic, and health-system heterogeneity. Quantifying contemporary trends and their drivers is essential for region-tailored policy. We aimed to provide the first continent-wide, methodologically harmonized assessment of temporal trends, demographic-epidemiologic determinants, and projections of IBD burden in Asia. Methods: We extracted country-specific incidence, prevalence, mortality, and disability-adjusted life-years (DALYs) for 1990-2021 from the Global Burden of Disease 2021 for 43 Asian countries/territories. Age-standardized rates (ASRs) were summarized using estimated annual percentage change (EAPC). An additive Das-Gupta decomposition apportioned absolute changes in cases and DALYs to population growth, population ageing, and epidemiologic change. Bayesian age-period-cohort models projected burden to 2040. Results: From 1990 to 2021, prevalent IBD cases more than doubled (0.54 million→1.34 million) and incident cases nearly tripled. Age-standardized prevalence (ASPR) and incidence (ASIR) rose by 25 % (EAPC 0.98 %) and 34 % (EAPC 1.17 %), respectively. In contrast, the age-standardized death rate declined from 0.50 to 0.30 per 100 000 (EAPC -1.97 %), and the DALY rate fell by 32 % (16.1 → 11.0 per 100 000; EAPC -1.30 %). Decomposition attributed 56 % of additional prevalent cases to population growth, 20 % to ageing, and 24 % to rising age-specific rates. East Asia showed the fastest proportional rise in ASIR yet the steepest DALY decline; Central Asia maintained the highest per-capita disability load; and Southeast Asia remained a low-burden plateau. Projections indicate continued prevalence growth in South and Central Asia, epidemiologic stabilization in East Asia, and sustained low burden in Southeast Asia by 2040. Conclusions: Asia is experiencing a dual dynamic of expanding IBD caseload alongside improving survival and disability outcomes, with pronounced sub-regional heterogeneity. Demography remains the principal driver of case growth, but genuine increases in age-specific incidence signal ongoing propagation of risk. Strengthening surveillance, expanding equitable access to advanced therapies, and implementing region-specific, longitudinal care pathways are imperative to avert disproportionate future disability and economic loss.