Global, regional, and national burden of NAFLD in adults aged 20–49 years (1990–2021): a comprehensive analysis of trends, decomposition, and health inequality

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is a growing global health concern, particularly among adults aged 20-49 years. However, comprehensive assessments of its burden in this demographic remain limited. METHODS: Data from the Global Burden of Disease (GBD) 2021 study were analyzed, covering 204 countries from 1990 to 2021. Incidence, prevalence, deaths, and disability-adjusted life years (DALYs) were examined, with results stratified by sex, age, and socio-demographic index (SDI) quintiles. Trend, decomposition, and inequality analyses were conducted, and future projections for 2022-2050 were generated using Exponential Smoothing (ES) and Autoregressive Integrated Moving Average (ARIMA) models. RESULTS: In 2021, NAFLD affected 48.31 million incident and 1.27 billion prevalent cases, causing 97,403 deaths and 2.67 million DALYs among adults aged 20-49. Both incidence and prevalence rose globally, with higher rates in males and the largest rises in middle-SDI countries, especially in Latin America and the Middle East. Forecasting models predict continued growth, especially among females, with a projected 60% increase in prevalence by 2050. Decomposition analysis showed that population growth was the primary driver, especially in middle and low-middle SDI regions, while epidemiological factors contributed more in high-SDI regions. Health inequality assessments revealed widening disparities, with the Slope Index of Inequality (SII) increasing, highlighting a greater burden in low-SDI countries. CONCLUSION: NAFLD imposes a rising burden on adults aged 20-49 years globally, exacerbated by demographic shifts and socioeconomic disparities. Targeted interventions addressing obesity, metabolic health, and healthcare access are urgently required to mitigate this growing public health challenge.