Comparison of Noninvasive Markers of Fibrosis in Patients With Nonalcoholic Fatty Liver Disease

Abstract

Background There is a need for a reliable and inexpensive noninvasive marker of hepatic fibrosis in nonalcoholic fatty liver disease (NAFLD). Aim To compare the performance of the FIB4 index (based on age, aspartate and alanine aminotransferase and platelet counts) with six other non-invasive markers of fibrosis in patients with NAFLD. Methods Using a nation-wide database of 541 adults with NAFLD, jackknife-validated areas under receiver operating characteristic curves (AUROC) of FIB4 and seven other markers were compared. The sensitivity at 90% specificity, 80% positive predictive value, and 90% negative predictive values were determined along with cutoffs for advanced fibrosis. Results The median FIB4 score was 1.11 (IQR=0.74–1.67). The jackknife-validated AUROC for FIB4 was 0.802 (95% CI: 0.758, 0.847) which was higher than that for the NAFLD fibrosis score (0.768 CI:0.720–0.816, p= 0.09), Goteburg University Cirrhosis Index (0.743, CI:0.695–0.791, p< 0.01), AST:ALT ratio (0.742, CI:0.690–0.794, p< 0.015), AST to platelet ratio index (0.730, CI:0.681–0.779, p< 0.001), AST to platelet ratio (0.720, 0.669–0.770, p< 0.001), BARD score (0.70, p< 0.001) and cirrhosis discriminant score (0.666, CI:0.614–0.718, p< 0.001). For a fixed specificity of 90% (FIB4 = 1.93), the sensitivity of identifying advanced fibrosis was only 50% (95% CI: 46, 55). A FIB4 ≥ 2.67 had an 80% positive predictive value and a FIB4 index ≤ 1.30 had a 90% negative predictive value. Conclusions The FIB4 index is superior to seven other non-invasive markers of fibrosis in patients with NAFLD; however its performance characteristics highlight the need for even better non-invasive markers.