FibroScan-AST score for diagnosing fibrotic MASH: A systematic review and meta-analysis of diagnostic test accuracy studies

Background and aim: Following the approval of the first agent for the management of metabolic dysfunction-associated steatohepatitis (MASH), identification of patients with fibrotic MASH (MASH with NAS ≥ 4 and fibrosis stage ≥ 2) is crucial. We assessed the performance of FibroScan-aspartate aminotransferase (AST) score (FAST) for ruling in/out fibrotic MASH.

Methods: We searched Medline, Cochrane Library, Web of Science, Scopus, and gray literature sources up to January 11, 2024. Studies were eligible if they assessed the accuracy of FAST score for the detection of fibrotic MASH using biopsy as the reference standard at previously reported thresholds (FAST ≥ 0.67 for ruling-in and ≤ 0.35 for ruling-out fibrotic MASH). We calculated pooled sensitivity and specificity estimates for FAST thresholds alongside 95% confidence intervals following bivariate random- effects models. We assessed the certainty of evidence using the Grading of Recommendations Assessment, Development and Evaluation framework.

Results: We included 16 studies with 8838 participants. A FAST score ≥ 0.67 yielded a pooled specificity of 0.87 (0.82-0.90) while a FAST score ≤ 0.35 yielded a summary sensitivity of 0.88 (0.83-0.91). At a prevalence of 30%, the positive predictive value for ruling-in fibrotic MASH was 60% while the negative predictive value for ruling-out the target condition was 91%. AST levels, cirrhosis prevalence, and number of pathologists reviewing biopsies were sources of heterogeneity among studies. The certainty of evidence was low to very low.

Conclusions: FAST score can be used as a triage test for ruling out fibrotic MASH. Nevertheless, its low positive predictive value necessitates sequential testing for ruling-in fibrotic MASH.