Prevalence of High and Moderate Risk Nonalcoholic Fatty Liver Disease Among Adults in the United States, 1999–2016

Nonalcoholic fatty liver disease (NAFLD) subjects with fibrosis stage ≥2 are at high risk for mortality. We aimed to provide national estimates and temporal trends for NAFLD, based on different fibrosis severity.Data from the National Health and Nutrition Examination Survey (NHANES) (1999-2016) and NHANES III (1988-1994) were utilized. NAFLD was determined by ultrasound showing moderate to severe steatosis. For those without ultrasound, NAFLD was determined by the U.S. Fatty Liver Index score of ≥30. Hepatic fibrosis was assessed using Fibrosis-4 (FIB-4) score (FIB-4 <1.3 = low risk; FIB-4 1.3-2.67 = moderate risk; and FIB-4 >2.67 = high risk). Annual percent change (APC) was calculated by using the joinpoint regression model.From NHANES III, 10,854 individuals were included (mean age 43.5 years; 47.5% male; 75.7% non-Hispanic White) and 37.7% had NAFLD. Among them, based on FIB-4, 80% had low-risk, 18.6% had moderate-risk, and 1.4% had high-risk NAFLD. NAFLD with moderate or high risk was more likely to have hypertension, hyperlipidemia, diabetes, cardiovascular disease, and metabolic syndrome than was low-risk NAFLD (all P < .02). NAFLD prevalence increased from 29.5% in 1999-2000 to 40.3% in 2015-2016 (APC, 2.78%; P < .02), moderate-risk NAFLD increased from 6.26% to 14.17% (APC, 5.34%; P < .02), and high-risk NAFLD increased from 0.49% to 1.15% (APC, 9.72%; P < .02). Independent predictors of advanced fibrosis were age (OR, 1.11; 95% CI, 1.06-1.17; P = .001) and diabetes (OR, 2.28; 95% CI, 1.03-5.05; P = .04). Compared with low-risk NAFLD, high-risk NAFLD was associated with significantly increased all-cause (HR, 1.53; 95% CI, 1.09-2.15; P = .01), cardiovascular disease-specific (HR, 1.99; 95% CI, 1.22-3.24, P < .01) and liver-specific (HR, 4.57; 95% CI, 1.03-28.79; P = .04) mortality.The prevalence of moderate- or high-risk NAFLD is increasing and is associated with increased all-cause, liver-related, and cardiovascular mortality.