A Validation Study of Non-invasive Scoring Systems for Assessing Severity of Hepatic Fibrosis in a Cohort of South Indian Patients With Non-alcoholic Fatty Liver Disease

Introduction

Liver biopsy is the gold standard for diagnosing and staging non-alcoholic fatty liver disease (NAFLD), but liver biopsy has its limitations. Non-invasive tests (NITs) eliminate many of the drawbacks of liver biopsy. We did a retrospective observational study to validate the NAFLD Fibrosis Score (NFS score) and Fibrosis Score 4 (FIB-4 index) against the gold standard liver biopsy in a cohort of South Indian patients with NAFLD.

Aims

The aim of this study was to validate the diagnostic accuracy of non-invasive fibrosis scoring systems (FIB-4 index and NFS), compared to that of liver histology, to predict AF in a cohort of south Indian patients with NAFLD.

Material and methods

A retrospective observational analytical study of patients who had a liver biopsy with a diagnosis of NAFLD and had all the data for aetiology assessment and NIT calculation within 4 weeks of biopsy were included in the study. On liver biopsy, NAFLD was scored as per NIH's NASH committee grading system. NFS and FIB-4 index were calculated, and scores more than 0.676 and 2.67, respectively, were taken as the cut-off to predict advanced fibrosis (AF). The sensitivity, specificity, positive predictive value, negative predictive value, and area under the receiver operating characteristic curve for NFS score and FIB-4 score to diagnose AF were calculated.

Results

A total of 147 patients were included in the study. Of these, 56 (38.1%) patients had AF (Stage 3, 4). Patients with AF were more likely to be older and have diabetes mellitus (DM). Patients with AF had lower platelet count, higher aspartate aminotransferase (AST), lower albumin, and higher AST/alanine aminotransferase ratio. An NFS of >0.676 had a sensitivity of 68% and specificity of 100%, and an FIB-4 index of >2.67 had a sensitivity of 67% and specificity of 95.6 % in diagnosing AF in our study.

Conclusion

The non-invasive scoring systems NFS and FIB-4 index can be used as a bedside tool for diagnosing liver fibrosis in NAFLD allowing liver biopsy to be used in a more targeted manner for patients diagnosed with AF on NITs.