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

Abstract

IntroductionLiver biopsy is the gold standard for diagnosing and staging 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 non-alcoholic fatty liver disease 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. Material and MethodsA 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 (NASH CRN) grading system. NAFLD Fibrosis Score (NFS) and FIB-4 index were calculated and scores more than 0.676 and 2.67 respectively was taken as the cut-off to predict advanced fibrosis. The sensitivity, specificity, positive predictive value, negative predictive value and area under the ROC curve for NFS score and FIB-4 score to diagnose advanced fibrosis were calculated. ResultsA total of 147 patients were included in the study. Of these 56 (38.1%) patients had advanced fibrosis (Stage 3, 4). Patients with advanced fibrosis were more likely to be older and have DM. Patients with advanced fibrosis had lower platelet count, higher AST, lower albumin and higher AST/ALT ratio. The NFS of > 0.676 had a sensitivity of 68% and specificity of 100% and FIB-4 index of >2.67 had a sensitivity of 67% and specificity of 95.6 % in diagnosing advanced fibrosis in our study. ConclusionThe non-invasive scoring systems NAFLD Fibrosis Score (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 advanced fibrosis on NITs.