Global Trends and Future Projections in the Burden of Inflammatory Bowel Disease Among Adolescents and Young Adults (15-49 Years) From 1990 to 2021.

Aims: Inflammatory bowel disease (IBD) is an immune-mediated disorder with rising global incidence. Adolescents and young adults (15-49 years) bear major psychological, social, and economic burdens, yet few studies have examined their disease trends. We aimed to estimate global, regional, and national incidence, prevalence, mortality, and disability-adjusted life years (DALYs) of IBD in this age group and to project future burden. Methods and Results: Using data from the Global Burden of Disease 2021, we analyzed age-standardized rates of incidence, prevalence, mortality, and DALYs (ASIR, ASPR, ASMR and ASDR) among people aged 15-49 across 204 countries and territories. Estimated annual percentage changes, Joinpoint regression, and age-period-cohort modelling were employed to evaluate temporal patterns, while Bayesian modelling projected trends to 2050. Inequalities were evaluated using the Socio-demographic Index (SDI). In 2021, global ASIR was 5.01/100,000 and ASPR was 41.56/100,000. ASMR and ASDR were 0.13/10,000 and 13.56/100,000 person-years, respectively. From 1990 to 2021, ASIR and ASPR increased slightly overall, with the most rapid rise in East Asia. ASMR and ASDR declined globally but remained highest in Western Sub-Saharan Africa. SDI was positively correlated with incidence and prevalence, and negatively with mortality. Projections to 2050 indicate continued declines in incidence and prevalence, stable DALYs, and a slight increase in mortality. Conclusion: IBD remains a significant burden in people aged 15-49. Growing incidence in East Asia and sustained mortality in disadvantaged regions highlight the need for early diagnosis, equitable care, and targeted public health strategies.