Prevalence and factors associated with NAFLD detected by vibration controlled transient elastography among US adults: Results from NHANES 2017–2018

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is increasingly common in the adult population. In the United States, the overall burden of NAFLD is unknown due to challenges with population-level NAFLD detection. The purpose of this study was to estimate prevalence of NAFLD and significant NAFLD fibrosis and identify factors associated with them in the U.S. METHODS: Data came from the 2017–2018 cycle of National Health and Nutrition Examination Survey. We defined NAFLD by controlled attenuation parameter (CAP) scores of ≥248 dB/m in absence of excessive alcohol use and viral hepatitis. We defined significant fibrosis as Vibration controlled transient elastography (VCTE) liver stiffness measurements (LSM) value ≥7.9 kPa. We calculated the adjusted odds ratio (OR) and 95% confidential intervals (CI) for associations with NAFLD and significant NAFLD fibrosis using multivariable logistic regression. RESULTS: Overall, among 4,024 individuals aged ≥20 years included in the analysis, 56.7% had NAFLD by CAP. In comparison, when defined by elevated liver enzymes, NAFLD prevalence was 12.4%. The prevalence of significant NAFLD fibrosis by VCTE LSM was 14.5%. NAFLD prevalence increased with age, was higher among men than women and among Hispanics compared with non-Hispanic whites. Individuals who were obese, had metabolic syndrome (MetS) and type 2 diabetes were more likely to have NAFLD compared to those that who were not obese or without MetS/diabetes. Inadequate physical activity (OR = 1.57, 95% CI: 1.18–2.08) was also a factor associated with NAFLD. MetS, high waist circumstance, diabetes and hypertension were independently associated with significant NAFLD fibrosis. CONCLUSIONS: NAFLD and significant NAFLD fibrosis are highly prevalent in U.S. general population.