Supplementary Material for: Global Burden of Encephalitis from 1990 to 2021, Its Attributable Risk Factors, and Projections to 2045

Introduction: Encephalitis represents a significant and evolving global health threat. We aimed to estimate the spatiotemporal patterns of the encephalitis burden and its attributable risk factors at national, regional, and global levels, and to project future trends to guide targeted prevention and treatment programs. Methods: This study analyzed incidence, mortality, and disability-adjusted life years (DALYs) utilizing data from the Global Burden of Disease (GBD) Study 2021. Joinpoint regression modeling was employed to identify significant turning points in age-standardized rates (ASRs). A decomposition analysis was conducted to dissect the contributions of aging, population growth, and epidemiological changes to the overall burden. Furthermore, the Bayesian age-period-cohort (BAPC) model was applied to project the global trend of encephalitis from 2021 to 2045. Results: Although the global burden of encephalitis has generally declined over the past three decades, the reduction in ASRs ceased between 2012 and 2015. Projections indicate that ASRs will stabilize rather than continue to decline from 2021 to 2045. The disease burden remains disproportionately high in regions with a low-medium Socio-demographic Index (SDI). Demographic analysis identifies children and the elderly as high-risk populations, with low birth weight identified as a prominent risk factor for neonatal encephalitis burden. Conclusions: The decline in encephalitis ASRs reached an inflection point during 2012–2015, potentially driven by epidemiological shifts such as emerging infectious or autoimmune etiologies. The concentration of burden in low-medium SDI regions suggests a link to tropical distributions and healthcare disparities. Targeted interventions, including promoting vaccination, enhancing prenatal care, and creating smoke-free environments, are essential to mitigate the future burden of encephalitis.