The Association Between Nonalcoholic Fatty Liver Disease and Metabolic Abnormalities in The United States Population

Abstract

BACKGROUND: Prevalence of nonalcoholic fatty liver disease (NAFLD) and rate of advanced fibrosis among individuals with metabolic syndrome (MetS) and its individual metabolic abnormalities needs better understanding in the United States population. We aim to study these by using a large United States population database, the Third National Health and Nutrition Examination Survey (NHANES III). METHODS: A total of 11,674 individuals were included in our study cohort. NAFLD was defined as presence of moderate to severe hepatic steatosis on liver ultrasound in absence of viral hepatitis, significant alcohol use, elevated transferrin level, and medication use leading to hepatic steatosis. Advanced fibrosis among those with NAFLD was determined using noninvasive method, the NAFLD fibrosis score. MetS was defined based on the National Cholesterol Education Program Adult Treatment Panel III definition. RESULTS: The prevalence of NAFLD among included study cohort was 18.2% (95% confidence interval, 16.5-19.9). Individuals with metabolic abnormalities demonstrated higher prevalence (MetS, 43.2%; increased waist circumference, 31.2%; impaired fasting glucose/diabetes, 41.2%; high triglyceride level, 34.7%; low high-density lipoprotein, 27.8%; high blood pressure, 29.2%). The individuals with MetS had significantly higher NAFLD prevalence compared with controls (adjusted odds ratio, 11.5; 95% confidence interval, 8.9-14.7). The severity of hepatic steatosis was also noted to increase with higher number of metabolic abnormalities. Among individual metabolic abnormalities, increased waist circumference, impaired fasting glucose/diabetes, high triglyceride, and low high-density lipoprotein levels were found to be independently associated with NAFLD. Individuals with impaired fasting glucose/diabetes and those with 5 metabolic abnormalities had higher rate of advanced fibrosis (18.6% and 30.3%, respectively). Prevalence of NAFLD among individuals without any metabolic abnormality was 6.1%. CONCLUSION: Prevalence of NAFLD and rate of advanced fibrosis are significantly high among individuals with metabolic abnormalities.