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

## TL;DR

This study compares FIB-3 and FIB-4 as tools for liver fibrosis screening in workplace health checkups, finding FIB-3 to be effective and less influenced by age.

## Contribution

The study demonstrates FIB-3's high negative predictive value and strong concordance with FIB-4 across age groups in a large worker cohort.

## Key findings

- FIB-3 showed 99.9% negative predictive value at FIB-4 ≥1.30 and 98.2% at FIB-4 ≥2.67.
- FIB-3 maintained strong concordance with FIB-4 across all age groups.
- Elevated AST and alcohol intake were linked to false-positive FIB-3 results.

## Abstract

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.

Key points

What is already known on this topic: FIB-4 is a widely used noninvasive index for liver fibrosis screening and has a high negative predictive value, but its inclusion of age can result in false positives among older individuals. There is a growing need for age-independent markers like FIB-3 in workplace health screenings.

What this study adds: This study showed that FIB-3 maintains a high negative predictive value and strong concordance with FIB-4 across age groups in a large cohort of workers. It effectively excludes fibrosis in individuals with elevated alanine aminotransferase and avoids the age-related inflation observed with FIB-4. Factors such as elevated aspartate aminotransferase and alcohol consumption were associated with false-positive FIB-3 results.

How this study might affect research, practice, or policy: FIB-3 may reduce unnecessary referrals for older workers and support more efficient liver screening during routine occupational health checkups. These findings encourage incorporating FIB-3 and platelet counts into standard health assessments and call for further validation with pathological data.