This cross-sectional study examined the prevalence and characteristics of steatotic liver disease (SLD) based on a recently introduced nomenclature in the Japanese health checkup population. SLD was evaluated using liver ultrasonography, and participants were categorized into metabolic dysfunction-associated steatotic liver disease (MASLD), metabolic dysfunction and alcohol associated steatotic liver disease (MetALD), alcohol-associated/related liver disease (ALD), and cryptogenic SLD groups. The prevalence and characteristics of the SLD subclasses were assessed, and subgroup analyses were conducted for the non-obese (body mass index [BMI] ≤ 25 kg/m2) and lean (BMI ≤ 23 kg/m2) populations. Among the 694 participants, with a median age of 47 years and comprising 54% males, the prevalence of MASLD, MetALD, ALD, and cryptogenic SLD was 26%, 2%, 1%, and 2%, respectively. A remarkable difference was observed in the prevalence of SLD subclasses according to age, sex, and BMI. Subgroup analyses revealed heterogeneous demographic, clinical, and biochemical parameters between the SLD categories. Individuals with MetALD had higher gamma-glutamyl transferase levels, lower platelet counts, and higher fibrosis-4 index than did those with MASLD. Furthermore, the prevalence of non-obese and lean MASLD was 13% and 6%, respectively. This study provides preliminary information on the prevalence of SLD based on a new nomenclature in the Japanese population.
Keywords: lean; metabolic dysfunction-associated fatty liver disease; nonalcoholic fatty liver disease; nonalcoholic steatohepatitis; nonobese; obesity.