Identification of risk groups for advanced liver fibrosis in the general population using the Fibrosis-3 index.

Background and Aim: We conducted a study using the Fibrosis-3 (FIB-3) index, which is the established age-independent index of fibrosis in nonviral liver disease and addresses the limitations of the FIB-4 index in older age group, to assess the liver fibrosis risk among diverse demographic groups in the general population. Methods: We analyzed 31 327 individuals who underwent health examinations between 2013 and 2020 and investigated the distribution of the FIB-3 index by age group. In addition, we examined the age distribution of the FIB-3 index stratified by background factors, such as sex, body mass index (BMI), alcohol consumption habits, and the presence or absence of fatty liver. Results: In terms of age-specific distribution, the FIB-3 index remained below 1.5 in >90% of cases until the age of 50 years but exceeded 1.5 beyond the age of 50 years, in approximately 30% among those aged 70 years. Notably, the FIB-3 index above 31 years old was significantly higher in men than in women. Among the different BMI categories, individuals with BMI < 18.5 exhibited the highest prevalence of fibrosis. Habitual drinkers had a higher proportion with FIB-3. index ≥1.5, and some had FIB-3 index ≥2.5, raising the suspicion of advanced hepatic fibrosis. No distinct association was identified between the FIB-3 index and the presence of fatty liver. Conclusions: The FIB-3 index was useful for identifying cases of advancing hepatic fibrosis in a health checkup population. Liver fibrosis progresses with age in the general population, especially among men, those with low BMI, and habitual drinkers.