Temporal Heterogeneity and Driving Factors of Idiopathic Epilepsy Incidence in BRICS Countries: A Population-Based Age-Period-Cohort Analysis.

BACKGROUND: Idiopathic epilepsy differs from secondary epilepsy in prognosis and prevention. The BRICS countries (Brazil, Russia, India, China, and South Africa) encompass diverse levels of economic development, sociocultural contexts, and healthcare systems. An in-depth analysis of long-term idiopathic epilepsy trends in BRICS can help reveal regional differences and key driving factors. METHODS: Using Global Burden of Disease (GBD) 2021 data, we analyzed idiopathic epilepsy incidence in BRICS countries from 1992 to 2021. We applied an age-period-cohort (APC) model to estimate age, period and cohort effect on incidence and calculated net drift, local drift, and relative risk (RR). Analyses were stratified by age group, sex, and country. RESULTS: In 2021, global incident cases of idiopathic epilepsy reached 2.90 million, with an age-standardized incidence rate (ASIR) of 37.63 per 100,000 population and an average annual percent change of 0.45. APC analysis revealed incidence rates increased in all BRICS countries (net drift > 0) except South Africa. Local drift generally followed an age-stratified pattern, fluctuating in individuals aged 0-64 years and rising in those aged 65-100. Gender differences were notable: incidence increased more rapidly in Chinese males than females, whereas in Russia, local drift peaks differed by sex among individuals aged ≥65 years. All BRICS countries exhibited a bimodal age effect. Period effects showed an inflection in Brazil around 2007-2012, a continuous increase in India, and relative stability in the remaining countries. Cohort effects rose gradually in India, followed a "rise-then-fall" pattern in Russia, were lower in South Africa, higher in China, and stable in Brazil. CONCLUSIONS: Idiopathic epilepsy incidence in BRICS countries demonstrates significant heterogeneity. Temporal trends are shaped by perinatal health, demographic changes, healthcare improvements, and sociocultural factors. Targeted interventions for high-risk populations are critical to reduce disease burden and optimize resource allocation.