Simple Noninvasive Scores Are Clinically Useful to Exclude, Not Predict, Advanced Fibrosis: A Study in Turkish Patients with Biopsy-Proven Nonalcoholic Fatty Liver Disease

BACKGROUND/AIMS: Advanced fibrosis (F≥3) indicates poor outcomes in nonalcoholic fatty liver disease (NAFLD). Here, we examined the diagnostic performance of the fibrosis-4 index (FIB-4) and NAFLD fibrosis score (NFS) for detecting (or excluding) advanced fibrosis in patients with biopsy-proven NAFLD. METHODS: The diagnostic performance of each noninvasive test according to previously identified cutoff points indicating low and high risk for advanced fibrosis was determined in 463 patients with NAFLD. Patients who scored <1.3 and >2.67 on the FIB-4 were considered at low and high risk for advanced fibrosis, respectively. Patients who scored <–1.455 and >0.676 on the NFS were considered at low and high risk for advanced fibrosis, respectively. RESULTS: Eighty-one patients (17.5%) had biopsy-proven advanced fibrosis (F≥3). The published FIB-4 cutoff values for low and high risk were able to exclude advanced fibrosis with negative predictive values (NPVs) of 0.907 and 0.843 and specificities of 74% and 97%, respectively. The published NFS cutoff values for low and high risk were able to exclude advanced fibrosis with NPVs of 0.913 and 0.842 and specificities of 63% and 96%, respectively. If biopsies were performed in only patients with a FIB-4 above the low cutoff point (≥1.3), 67.1% could be avoided. Conversely, if biopsies were performed in only patients with an NFS above the low cutoff point (≥–1.455), 57.0% could be avoided. CONCLUSIONS: The main clinical utility of the FIB-4 and NFS in patients with NAFLD lies in the ability to exclude, not identify, advanced fibrosis.