Purpose: Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide, and it is the hepatic manifestation of metabolic syndrome (MetS). We aimed to estimate the prevalence of NAFLD defined by the fatty liver index (FLI), in order to investigate the association between FLI and metabolic disorders and to determine the cutoff value of FLI to screen for MetS.
Subjects and methods: This study utilized a national representative sample of Korean adults (the Korean National Health and Nutrition Examination Surveys) which was conducted in 2010-2011. A total of 10,107 adults aged 19 years or older were selected. NAFLD was diagnosed on the basis of an increased FLI (≥60) after the exclusion of alcohol or viral liver disease.
Results: NAFLD was identified in 1,134 subjects (age-standardized prevalence, 10.0%). When subjects were categorized into three groups by FLI (<20, 20-59, and ≥60), the higher FLI group showed a higher prevalence of hypertension (49.7% vs 14.4%), diabetes mellitus (DM; 20.4% vs 3.8%), and MetS (74.9% vs 7.4%). FLI was positively associated with age, body mass index, blood pressure, hemoglobin A1c, and homeostasis model assessment of insulin resistance (P for trend <0.001). In the multivariate analysis, the higher FLI group had a significantly higher risk for hypertension (OR =2.92, 95% CI =2.18-3.90, P<0.001), DM (OR =4.38, 95% CI =2.96-6.49, P<0.001), and MetS (OR =24.85, 95% CI =17.33-35.64, P<0.001). However, no increase was observed for cardiovascular disease after adjustment of other risk factors. The cutoff value of the FLI estimated to predict the presence of MetS was 20 (area under the curve 0.849, sensitivity 0.828, and negative predictive value 91.9%).
Conclusion: NAFLD prevalence using FLI is significantly higher in subjects with metabolic disorder including MetS. FLI might be a useful screening tool to detect subjects who may require early management of MetS and who have a high cardiovascular risk.
Keywords: cardiovascular disease; diabetes mellitus; hypertension; metabolic syndrome; nonalcoholic fatty liver disease.