Systematic study and 30-year projections of global and multi-regional burden of multiple sclerosis, 1990-2021

Multiple sclerosis (MS) is a chronic neurodegenerative disease with significant temporal and regional heterogeneity. While earlier studies described the burden before 2019, recent shifts influenced by socioeconomic development, healthcare access, and environmental exposures remain unclear. Using the Global Burden of Disease database, we analyzed recent MS trends, assessed interactions of gender, age, and sociodemographic index (SDI), and projected future dynamics. Based on the Global Burden of Disease database from 1990 to 2021, this study collected epidemiological data of 2795 patients with MS from 204 countries and regions, covering core indicators such as incidence, prevalence, mortality, and disability-adjusted life years (DALYs). Data underwent standardized processing and WHO age-standardization. Long-term trends were analyzed with Joinpoint regression; regional variation by SDI and Moran I; gender and age distributions with chi-square; and inequalities by concentration indices and Lorenz curves. A Bayesian hierarchical model with Markov chain Monte Carlo was applied to forecast trends to 2050. From 1990 to 2021, global MS cases rose markedly (incidence +49.9%, prevalence +87.9%), but age-standardized incidence and prevalence remained stable (-3.5% and -0.4%), indicating population growth as the main driver. High-SDI regions showed rising incidence (Western Europe +27.8%, Latin America +31.6%), while low-SDI regions had sharp increases in case numbers but limited standardized rate changes. Mortality and DALYs decreased globally (-12.8% and -11.0%) but rose in resource-limited areas (mortality +110.9% in Central Latin America, DALYs +315% in West Africa). Women consistently bore a higher burden, with gender gaps most evident in low-income regions (315% higher mortality in West African women). MS prevalence strongly correlated with SDI (r = 0.6975, P < .001). Projections suggest gradual incidence growth with declining mortality and DALYs by 2050. Inequality analysis showed persistent deviations from equilibrium. Despite improved survival, high-SDI regions face the challenge of managing aging patients, while low-SDI regions suffer from high mortality and limited resources. The disproportionate burden in women, especially in low-income settings, underscores the need for tailored, equity-focused strategies.