Serum Fibrosis Marker Panels FIB-4 Index and Aspartate Aminotransferase (AST)-to-Platelet Ratio Index (APRI) Are Equivalent to AST Alone at Predicting Liver Fibrosis in a Cohort of 1731 Patients Infected with Hepatitis C Virus

Background Efficient tools are needed to stage liver disease before treatment of patients infected with hepatitis C virus (HCV). Compared to biopsy, several studies demonstrated favorable performance of noninvasive multianalyte serum fibrosis marker panels [fibrosis-4 (FIB-4) index] and aspartate aminotransferase (AST)-to-platelet ratio index (APRI), but suggested cutoffs vary widely. Our objective was to evaluate FIB-4 index and APRI and their component tests for staging fibrosis in our HCV-infected population and to determine practical cutoffs to help triage an influx of patients requiring treatment. Methods Transient elastography (TE) results from 1731 HCV-infected patients were mapped to an F0–F4 equivalent scale. Each patient's APRI and FIB-4 index were calculated. Areas under the receiver operator curve (AUROCs) and false-positive and false-negative rates were calculated to retrospectively compare the performance of the indices and their component tests. Results The highest AUROCs for distinguishing severe (F3–F4) from mild-to-moderate (F0–F2) fibrosis had overlapping 95% CIs: APRI (0.77; 0.74–0.79), FIB-4 index (0.76; 0.73–0.78), and AST (0.74; 0.72–0.77). Cutoffs had false-negative rates of 2.7%–2.8% and false-positive rates of 6.4%–7.4% for all 3 markers. Conclusions AST was as effective as FIB-4 index and APRI at predicting fibrosis. Published cutoffs for APRI and FIB-4 index would have been inappropriate in our population, with false-negative rates as high as 11%. For our purposes, no serum fibrosis marker was sufficiently sensitive to rule-out significant fibrosis, but cutoffs developed for AST, FIB-4 index, and APRI all had specificities of 79.2%–80.3% for ruling-in severe fibrosis and could be used to triage 1/3 of our population for treatment without waiting for TE or liver biopsy.