Supplemental Material for: Global Age-Shift and Growing Inequities in the Idiopathic Epilepsy Burden Among Children and Adolescents (0–19 Years), 1990–2050

Methods

Using data from the Global Burden of Disease (GBD) Study 2021, we analyzed incidence, prevalence, deaths, and disability-adjusted life years (DALYs) for IE across 204 countries and territories. Temporal trends were evaluated using Joinpoint regression to estimate Average Annual Percent Changes (AAPC). We employed bivariate spatial analysis to intersect IE burden with COVID-19 intensity, and quantified health inequalities using the Slope Index of Inequality (SII) and Concentration Index.

Future projections were generated via Bayesian Age-Period-Cohort (BAPC) models. Results: In 2021, the global age-standardized prevalence of IE reached 321.41 per 100,000, representing an 8.03% increase since 1990 (AAPC = 0.25%; 95% CI: 0.07%–0.43%). While age-standardized death rates decreased by 21.67% (AAPC = -0.79%; 95% CI: -0.99% to -0.58%) and DALY rates fell by 15.57% (AAPC = -0.54%; 95% CI: -0.72% to -0.37%), global incidence rose slightly (AAPC = 0.30%; 95% CI: 0.12%–0.47%).

A shift in the demographic distribution of the disease burden was observed: the primary burden migrated from the <5 age group in 1990 to the 15–19 age group in 2021, likely driven by declining early-childhood mortality. Bivariate spatial analysis identified 29 countries exhibiting geographic overlap between high baseline IE endemicity and intense COVID-19 impact. Inequality indices (SII and Concentration Index) confirmed a progressive consolidation of health loss within low socio-demographic index (SDI) regions.

By 2050, despite projected declines in rates, absolute DALY counts are expected to remain high in low-resource settings due to demographic momentum. Conclusions: The global IE landscape among the 0–19 population has transitioned into a "post-mortality" phase, characterized by improved survival but expanding chronic disability, particularly among late adolescents (15–19 years). The disproportionate burden in low-SDI regions and the systemic vulnerabilities highlighted during the COVID-19 pandemic necessitate a paradigm shift from acute intervention to longitudinal, age-specific care and the urgent closure of the global "treatment gap."</p>