Validation of Novel Fibrosis Index (NFI) for assessment of liver fibrosis: comparison with transient elastography (FibroScan)

Background In this study, we collated cheap and readily available non-invasive biomarkers and FibroScan score in predicting fibrosis stages in chronic hepatitis C virus (HCV) infection. Methods We studied 1898 patients with HCV infection confirmed by presence of HCV RNA in their serum. We compared the FibroScan score and fibrosis indices (FIs): aspartate transaminase (AST) to alanine transaminase (ALT) ratio (AAR), AST to Platelet Ratio Index (APRI), FI, fibrosis-4 (FIB-4), Age-Platelet Index (API), Pohl score, Fibrosis Cirrhosis Index (FCI). We developed a new FI, named Novel Fibrosis Index (NFI) calculated by the following formula: NFI=[(bilirubinx(ALP)(2))/(platelet count (albumin)(2))]-n. Results AAR, APRI, FI, FIB-4, API, Pohl score, FCI and NFI were able to predict fibrosis stage with correlation coefficient indices 0.848, 0.711, 0.618, 0.741, 0.529, 0.360, 0.477 and 0.26, respectively. Receiver operating characteristic curves showed sensitivity and specificity for predicting F3 by NFI=75.1% and 41.1% and F4 for NFI=72.1% and 47.1%, AAR=62.8% and 37.6%, APRI=74.6% and 87.6%, FIB-4=53.2% and 72.3%, FI=78.1% and 92.3%, API=78.1% and 60%, Pohl score=38.1% and 78.1% and FCI=78.1% and 88.1%. Conclusions Our NFI predicted F3 and has been found to have more sensitivity and specificity in predicting F4 fibrosis stage than other FIs.