Prevalence, Trends, and Characteristics of Nonalcoholic Fatty Liver Disease among the US Population Aged 12–79 Years

Abstract Background & Aims: Clinical observation revealed an increase in nonalcoholic fatty liver disease (NAFLD) prevalence among adults and adolescents and young adults (AYA). However, its prevalence trend in specific subgroups and its characteristics are unclear. Approach & Results: This cross-sectional study included adults and AYA aged 20–79 and 12–19 years, respectively, from the National Health and Nutrition Examination Survey from 1999 to 2018. NAFLD was defined as US Fatty Liver Index ≥ 30 in adults and alanine amino transaminase elevation and obesity in AYA. Joinpoint and logistic regression were used to evaluate the NAFLD prevalence trend and its associated characteristics. NAFLD was diagnosed in 17,156,892 of 51,109,914 (33.6%) adults and 1,705,586 of 29,278,666 AYA (5.8%). During the study period, NAFLD prevalence significantly increased from 30.8–37.7% (P < 0.01) in adults and in subgroups of female participants, individuals aged 20–45 and 61–79 years, and non-Hispanic white individuals. Conversely, NAFLD prevalence did not significantly change in AYA (from 5.1–5.2%, P = 0.139), except in the subgroup of Mexican Americans (from 8.2–10.8%, P = 0.01). Among adults, high NAFLD prevalence was associated with male sex, Mexican American ethnicity, age > 50 years, being unmarried, poverty income ratio < 130, poor or fair health condition, obesity or overweight, and chronic conditions. Among AYA, high NAFLD prevalence was associated with male sex, poverty income ratio < 130, and education. Conclusions: Accordingly, we concluded that health care providers should prevent and treat conditions associated with NAFLD by raising awareness of the increasing trend of NAFLD.