Three-decade trends in nonalcoholic fatty liver disease across 204 countries and territories: An age-period-cohort analysis from 1990 to 2021.

Nonalcoholic fatty liver disease (NAFLD) has emerged as a leading chronic liver disease globally, driven by the rising incidence of obesity, type 2 diabetes, and metabolic syndrome. Despite the increasing burden, most studies focus on prevalence rather than incidence, leaving a gap in understanding temporal patterns of NAFLD incidence. We conducted an age-period-cohort analysis of NAFLD incidence across 204 countries and territories from 1990 to 2021, utilizing data from the Global Burden of Disease Study 2021. Incidence rates were standardized per 100,000 person-years and analyzed by age, sex, region, and socio-demographic index (SDI). The global incidence of NAFLD nearly doubled from 24.9 million cases in 1990 to 48.4 million in 2021. The age-standardized incidence rate in 2021 was 593.28 per 100,000 population (95% confidence interval: 542.72-643.7). Middle SDI regions recorded the highest incidence rate (695/100,000), while low SDI regions had the lowest (483/100,000). The age-period-cohort model indicated a net drift of 0.56% (95% confidence interval: 0.53-0.6) globally. NAFLD incidence has risen substantially over the past 3 decades, particularly in middle-income regions. These findings highlight the need for targeted public health interventions and further research to address the growing global burden of NAFLD.