Study design and population

We retrospectively enrolled participants for this cross-sectional study from the ongoing MedCity21 health examination registry between April 1, 2014 and December 31, 2019. This registry protocol is a comprehensive agreement. The study design was approved by the Ethical Committee of Osaka City University Graduate School of Medicine (approval no. 2927)²¹. Furthermore, this cross-sectional study of liver disease was part of the MedCity21 health examination registry and was conducted in full accordance with the tenets of the 1975 Declaration of Helsinki (6th revision, 2008). The study protocol was approved by the Ethical Committee of Osaka City University Graduate School of Medicine (approval no. 2019–076, February 21, 2020). The Ethical Committee of Osaka City University Graduate School of Medicine waived the need for written and verbal approved informed consent from the enrolled participants because this was a retrospective observational study using only existing information. Instead, we provided an opt-out option, explained in the instructions posted on the hospital’s website.

This study initially included participants (n = 3425) who had undergone a medical examination, including abdominal ultrasonography and LSM, for the first time during the aforementioned study period. The exclusion criteria were: lack of data regarding hepatitis B surface antigen (HBsAg)/anti-hepatitis C antibody (HCV-Ab) (n = 373); a success rate (SR) < 60% (n = 365); LSM with an interquartile range (IQR) or median > 30% (n = 181); positive serology results for HBsAg (n = 80): alcohol intake ≥ 60 g/day (n = 74); positive serology results for HCV-Ab (n = 41); lack of data regarding glycated hemoglobin (HbA1c) (n = 42); and lack of data regarding platelet counts (n = 15). After exclusion, a total of 2,254 participants were analyzed (Fig. 1).