Limited Accuracy of Noninvasive Tests in Posttransplant Liver Fibrosis Assessment

Since the early 2000s, noninvasive tests (NITs) such as serum biomarkers (eg, fibrosis index based on the 4 factors [FIB-4], aspartate aminotransferase-to-platelet ratio index) and imaging techniques such as transient elastography (FibroScan) have been used to assess hepatic fibrosis. Although they have been validated in pretransplant cohorts, their posttransplant accuracy remains uncertain.

To assess concordance between liver biopsy (LBx) and 2 widely used NITs-FibroScan and FIB-4-and identify drivers of discordance in the posttransplant setting.

Adult liver transplant recipients who underwent LBx (2015-2024), with FibroScan data available within 6 months and laboratory values available within 1 month, were included. Stage of trichrome fibrosis, percentage steatosis, liver stiffness measurement, and FIB-4 scores were analyzed. Concordant and discordant cases were compared.

Among 108 patients (median age, 63 years; range, 27-76 years), common diagnoses included recurrent (n = 49; 45.4%) and de novo (n = 29; 26.8%) steatotic liver disease (SLD), recurrent chronic hepatitis C (n = 9; 8.3%), and allograft rejection (n = 8; 7.4%). Median fibrosis was stage 1 by LBx, whereas median liver stiffness measurement and FIB-4 corresponded to stage 2. Overall, correlation with LBx was low (r = 0.227, P = .02 for FibroScan; r = 0.077, P = .43 for FIB-4). FibroScan overestimated fibrosis in 23.8% (21 of 88) of early-stage and underestimated 30% (6 of 20) of advanced fibrosis. FIB-4 misclassified 29.5% (26 of 88) without advanced fibrosis as F3 through F4 and missed 45% (9 of 20) with advanced fibrosis.

NITs show limited concordance with LBx in posttransplant fibrosis assessment. Discrepancies may stem from confounders such as severe steatosis, body mass index 30 kg/m2 or higher, inflammation, rejection, infiltrative processes (eg, amyloidosis), and nodular regenerative hyperplasia (NRH).