The first external validation of the Dallas steatosis index in biopsy-proven Non-alcoholic fatty liver Disease: A multicenter study

Aims: A new non-invasive tool (NIT) for non-alcoholic fatty liver disease (NAFLD) proposed in 2022 by the multi-ethnic Dallas Heart Study, i.e. the Dallas Steatosis Index (DSI), was validated herein using for the first time the gold standard i.e. liver biopsy-proven NAFLD.Methods: This is a multicenter study based on samples and data from two Gastroenterology-Hepatology Clinics (Greece and Australia) and one Bariatric-Metabolic Surgery Clinic (Italy). Overall, n = 455 patients with biopsy-proven NAFLD (n = 374) and biopsy-proven controls (n = 81) were recruited.Results: The ability of DSI to correctly classify participants as NAFLD or controls was very good, reaching an Area Under the Curve (AUC) = 0.887. The cut-off point that could best differentiate the presence vs. absence of NAFLD corresponded to DSI = 0.0 (risk threshold: 50% | Sensitivity: 0.88; Positive Predictive Value (PPV): 93.0%; F1-score = 0.91). DSI demonstrated significantly better performance characteristics than other liver steatosis in-dexes. Decision curve analysis revealed that the benefit of DSI as a marker to indicate the need for invasive liver assessment was confirmed only when higher DSI values, i.e. = 1.4, were used as risk thresholds. DSI performance to differentiate disease progression was inadequate (all AUCs < 0.700).Conclusions: DSI is more useful for disease screening (NAFLD vs. controls) than to differentiate diseases stages or progression. The value of any inclusion of DSI to guidelines needs to be further studied.