Overall and subgroup prevalence of non-alcoholic fatty liver disease and prevalence of advanced fibrosis in the United States: An updated national estimate in National Health and Nutrition Examination Survey (NHANES) 2011-2018

Abstract

Introduction and objectives: Data on the prevalence of non-alcoholic fatty liver disease (NAFLD) in subgroups of the United States (US) population are limited. This study was conducted to estimate NAFLD prevalence overall and by subgroups, and prevalence of NAFLD with advanced fibrosis.

Materials and methods: Using the National Health and Nutrition Examination Survey (NHANES) 2011-2018 data, a cross-sectional study was conducted. NAFLD was defined as having a US Fatty Liver Index (USFLI) ≥ 30 in the absence of other causes of liver disease, including excessive alcohol intake, chronic hepatitis B, and chronic hepatitis C. Likelihood for having advanced fibrosis was determined by the calculated NAFLD fibrosis score (NFS; high ≥ 0.676; low < -1.445) and fibrosis-4 index (FIB-4; high ≥ 2.67; low < 1.30).

Results: The weighted national prevalence of NAFLD in US adults was 26.7% (95% confidence interval: 25.3%-28.1%). Prevalence was higher among those aged ≥ 65 years, males, Mexican Americans, with BMI ≥ 35 kg/m² (class 2 and 3 obesity) and with type 2 diabetes (T2D). Of those meeting the USFLI criterion for NAFLD, 18.1% and 3.7% were determined as having a high probability of advanced fibrosis based on NFS ≥ 0.676 and FIB-4 ≥ 2.67 cut-off values, respectively.

Conclusions: This study supports an increased prevalence of NAFLD in specific subpopulations (aged ≥ 65 years, males, Mexican Americans, obese population, and patients with T2D). The observed difference in the prevalence of advanced fibrosis as estimated by NFS and FIB-4 highlights the challenge of choosing optimal cut-off values.

Keywords: FIB-4 index; MASLD; NAFLD; NFS.