Disease burden of rheumatoid arthritis in the context of population aging: A comparative analysis of China, Japan, the United States and India

Background and objectives: As worldwide population aging accelerates, the burden of rheumatoid arthritis (RA) continues to increase. This study compared the spatiotemporal trends and underlying drivers of the RA burden across four countries with different levels of socioeconomic development under population aging.

Methods

Using data from the Global Burden of Disease (GBD) 2021 study, we analyzed age-standardized rates of incidence, prevalence, mortality, and disability-adjusted life years (DALYs) for RA in China, Japan, the United States, and India from 1990 to 2021. Temporal trends were assessed using Joinpoint regression. A decomposition model was applied to quantify the contributions of population growth, population aging, and epidemiological changes to the overall burden. Spearman correlation analysis was performed to evaluate the association between RA burden indicators and the Sociodemographic Index (SDI). The Nordpred model was employed to project age-standardized prevalence rates among individuals aged 60 years and older up to 2046.