ABSTRACT
AIM: The prevalence of nonalcoholic fatty liver disease (NAFLD) is increasing worldwide. The aim of this study was to determine the recent prevalence and clinical characteristics of NAFLD in Japan. METHODS: This study initially included 410 061 retrospectively enrolled adults from the medical health checkup registry for metabolic syndrome, chronic kidney disease, and fatty liver in Japan (MIRACLE-J; UMIN-CTR no. UMIN000049419), who were evaluated between 2014 and 2018 at 13 health centers in Japan. Individuals consuming >20 g of alcohol/day or with chronic liver disease were excluded. Fatty liver was diagnosed by ultrasonography. The probability of NAFLD with advanced fibrosis was estimated based on the fibrosis-4 index and NAFLD fibrosis score. RESULTS: A total of 71 254 participants were included in the final analysis. The overall prevalence of NAFLD was 25.8%. There was a significant, twofold difference in NAFLD prevalence between men (37.4%) and women (18.1%). Nonalcoholic fatty liver disease prevalence increased linearly with body mass index, triglycerides, and low-density lipoprotein cholesterol regardless of threshold values, even in the absence of obesity. Among patients with NAFLD, 14% had diabetes mellitus, 31% had hypertension, and 48% had dyslipidemia. The estimated prevalence of NAFLD with advanced fibrosis was 1.7% and 1.0% according to the fibrosis-4 index and NAFLD fibrosis score, respectively. CONCLUSIONS: The prevalence of NAFLD was approximately one-quarter of the general population in Japan. There was a linear relationship between NAFLD prevalence and various metabolic parameters, even in nonobese participants. The prevalence of NAFLD with advanced fibrosis was estimated to be 1%-2%.
