Diverging trajectories of multiple sclerosis burden in postmenopausal women across East Asia: a comparative analysis of China, Japan, and the Republic of Korea from 1990 to 2050

BACKGROUND: Multiple sclerosis (MS) disproportionately affects women, and the hormonal shifts of menopause may influence its progression. However, a comprehensive evaluation of the MS burden specifically in postmenopausal women across East Asia is currently lacking. METHODS: Based on data from the Global Burden of Disease Study 2023, we assessed the epidemiology of MS in women aged 55 years and older in China, Japan, and the Republic of Korea, focusing on incidence, prevalence, mortality, and disability-adjusted life years (DALYs). The analysis comprised two key components: decomposition analysis to quantify the factors driving changes in disease burden, and Bayesian Age-Period-Cohort models to project the future burden through 2050. RESULTS: From 1990 to 2023, Japan consistently exhibited the highest burden, with its age-standardized prevalence rate (ASPR) increasing from 25.53 (95% UI: 21.01-30.06) to 46.23 (95% UI: 38.17-53.77) per 100,000. In contrast, China's ASPR rose from 3.22 (95% UI: 2.50-3.96) to 4.92 (95% UI: 3.96-5.89), while the Republic of Korea's rate remained stable, declining slightly from 7.55 (95% UI: 6.05-9.03) to 7.47 (95% UI: 7.19-7.75). Despite the decline in age-standardized incidence and mortality rates in China and the Republic of Korea, absolute case counts surged dramatically across all three nations. For instance, the number of prevalent cases in China increased by 343.7%, primarily driven by population growth, which contributed 65.26% to the change in prevalence. Japan was an outlier, exhibiting rising age-standardized incidence, mortality, and Disability-Adjusted Life Years (DALY) rates. Projections for 2050 indicate a continued rise in absolute burden, with China's prevalent cases expected to exceed 19,000 and Japan's ASPR anticipated to reach 65.3 (95% CI: 54.67-75.97) per 100,000. CONCLUSION: The burden of MS among postmenopausal women in East Asia is substantial and rising, exhibiting divergent patterns across countries. These findings underscore the urgent need for tailored, gender-sensitive healthcare policies and resource allocation to address the growing challenge of MS in aging female populations across the region.