Validation of the fibrosis-4 (FIB-4) index in the diagnosis of liver disease of rheumatoid arthritis patients treated with methotrexate.

To validate the usefulness of a hepatic fibrosis scoring system fibrosis-4 (FIB-4) index to diagnose liver diseases in rheumatoid arthritis (RA) patients treated with methotrexate (MTX). The FIB-4 index (age(years) × AST(U/L)/platelet (PLT) (10/L) × √ALT(U/L)), proposed as a predictor for liver fibrosis in HIV/HCV coinfection, was evaluated in this study. RA patients on MTX treatment were screened by FIB-4 index values to detect fibrotic change in the liver. Liver biopsy specimens were examined histologically in patients with high values. Thirteen of 14 patients showed histology closely resembling non-alcoholic steatohepatitis. In three of them, two biopsies were performed: 1st, during MTX treatment; and 2nd, after discontinuation of MTX. All of them showed improvement in histology along with decreased FIB-4 values. Age, AST/√ALT, and 1/PLT, as well as creatinine levels and cumulative MTX doses were significantly higher in the high FIB-4 group compared with the low FIB-4 group. In the high FIB-4 group, 1/PLT and AST/√ALT were significantly correlated with FIB-4 values, but age was not. The FIB-4 index is simple to calculate and a valuable marker to diagnose liver disease in RA patients treated with long-term MTX administration.