BACKGROUND & AIMS: There is a need for a reliable and inexpensive noninvasive marker of hepatic fibrosis in patients with nonalcoholic fatty liver disease (NAFLD). We compared the performance of the FIB4 index (based on age, aspartate aminotransferase [AST] and alanine aminotransferase [ALT] levels, and platelet counts) with 6 other non-invasive markers of fibrosis in patients with NAFLD. METHODS: Using a nation-wide database of 541 adults with NAFLD, jackknifevalidated areas under receiver operating characteristic curves (AUROC) of FIB4 and 7 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 (interquartile range = 0.74 -1.67). The jackknifevalidated AUROC for FIB4 was 0.802 (95% confidence interval [CI], 0.758 - 0.847), which was higher than that of the NAFLD fibrosis score (0.768; 95% CI, 0.720 - 0.816; P = .09), Goteburg University Cirrhosis Index (0.743; 95% CI, 0.695- 0.791; P < .01), AST:ALT ratio (0.742; 95% CI, 0.690 - 0.794; P < .015), AST:platelet ratio index (0.730; 95% CI, 0.681- 0.779; P < .001), AST:platelet ratio (0.720; 95% CI, 0.669 - 0.770; P < .001), body mass index, AST:ALT, diabetes (BARD) score (0.70; P < .001), or cirrhosis discriminant score (0.666; 95% CI, 0.614 - 0.718; P < .001). For a fixed specificity of 90% (FIB4 = 1.93), the sensitivity in 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 7 other noninvasive markers of fibrosis in patients with NAFLD; however its performance characteristics highlight the need for even better noninvasive markers.
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