Evaluation of a novel albumin platelet product (APP) fibrosis index and three non-invasive fibrosis indices in metabolic dysfunction–associated steatotic liver disease

Background: Albumin platelet product (APP) is a novel blood-based biomarker for liver fibrosis staging. This study evaluates APP's performance against Fibrosis-4 index (FIB-4), AST–platelet ratio index (APRI), and aspartate aminotransferase–alanine aminotransferase (AST/ALT) ratio in diagnosing advanced fibrosis and cirrhosis in metabolic dysfunction–associated steatotic liver disease (MASLD) patients with and without diabetes (DM). Method: Adults with MASLD/metabolic dysfunction–associated steatohepatitis (MASH) in 2010–2023 and available fibrosis staging biomarkers were included. Clinical fibrosis staging was confirmed by liver biopsy, transient elastography (FibroScan), and/or magnetic resonance elastography. Fibrosis staging-matched fibrosis biomarkers were calculated and analyzed. Results: A total of 570 patients (48.6% male) with available clinical staging and biomarkers were analyzed. DM was present in 38% of the cohort with a significantly higher prevalence among those with advanced fibrosis or cirrhosis ( p < 0.001). APP and FIB-4 showed comparable diagnostic performance with areas under the curve (AUCs) of 0.85 (95% CI 0.82–0.88) and 0.84 (95% CI 0.81–0.87), both significantly outperforming APRI and AST/ALT ratio (AUC 0.76, p < 0.05). Importantly, all AUCs were significantly lower in the DM cohort. In patients with DM, APP outperformed FIB-4 in detecting cirrhosis (AUC 0.80 versus 0.76, p = 0.04) and was comparable for advanced fibrosis. In the non-DM cohort, APP and FIB4 performed similarly (AUCs 0.84–0.89, p > 0.05). Conclusion: APP outperformed FIB4 in detecting cirrhosis or advanced fibrosis among patients with DM and was comparable in non-DM patients. Revised FIB-4 thresholds may be needed in MASLD/MASH patients with DM to improve its diagnostic accuracy.