Comparative evaluation of FIB-3 and FIB-4 indices for liver fibrosis screening in workplace-based health checkups

To examine the utility of the FIB-3 index as a secondary screening tool for liver fibrosis in workplace-based health checkups, by comparing its concordance and negative predictive values (NPVs) with those of the FIB-4 index.

This cross-sectional study included 12 622 workers from the Hitachi Cohort Study who underwent workplace-based health checkups between April 2021 and March 2022. FIB-4 was calculated using age, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and platelet count, whereas FIB-3 used the same components except age. To evaluate the utility of FIB-3 in excluding liver fibrosis, NPVs were calculated using FIB-4 thresholds (1.30, 2.01, and 2.67) as references. Concordance between FIB-3 and FIB-4 was examined across different age groups. In addition, multivariate logistic regression analysis was conducted to identify factors associated with false-positive FIB-3 results.

The FIB-3 index demonstrated high NPVs for excluding liver fibrosis, with values of 99.9% at FIB-4 ≥ 1.30 and 98.2% at FIB-4 ≥ 2.67. Strong concordance between FIB-3 and FIB-4 was observed consistently across different age groups. Among participants with elevated ALT (>30 IU/L), FIB-3 consistently ruled out fibrosis, whereas FIB-4 positivity increased with advancing age. Multivariate analysis indicated that higher AST levels and increased alcohol intake were significantly associated with false-positive FIB-3 results.

The FIB-3 index demonstrated stable performance across age groups while maintaining high concordance and NPV relative to FIB-4. These findings suggest that FIB-3 may serve as a practical screening tool in routine workplace-based health checkups, particularly in mitigating age-related overestimation observed with the FIB-4 index.