Fatty Liver Index (FLI) is the best score to predict MASLD with 50% lower cut-off value in women than in men

Background Metabolic dysfunction-associated steatotic liver disease (MASLD) is defined by the presence of hepatic steatosis, detected on ultrasonography (US) imaging or histology, and at least one of criteria for Metabolic Syndrome diagnosis. Simple non-invasive tests (NITs) have been proposed as an acceptable alternative when US and biopsy are not available or feasible but have not been validated for MASLD. In this observational study, we investigated the reliability of NITs for MASLD detection and whether sex-differences in screening methods should be considered.Methods We included 1069 individuals (48% males and 52% females) who underwent their first clinical examination for Metabolic Syndrome in the period between January 2015 and December 2022. Liver steatosis was detected through US and anthropometric and clinical parameters were recorded.Results Liver steatosis was detected in 648 patients and MASLD was diagnosed in 630 subjects (355 males; 275 females). Women with MASLD showed better metabolic profile and lower prevalence of Metabolic Syndrome criteria than men. Among NITs, Fatty Liver Index (FLI) showed the best ability for detection of MASLD, with a cut-off value of 44 (AUC = 0.82). When considering the two sexes for MASLD detection via FLI, despite no substantial differences regarding FLI correlations with metabolic biomarkers except for age, women showed marked lower FLI cut-off value (32; AUC = 0.80) than men (60; AUC = 0.80).Conclusions In this study, we found that FLI is the best non-invasive predictor of both liver steatosis and MASLD. The finding that in women FLI cut-off value for MASLD detection is 50% lower than in men suggests the need of a sex-specific personalized program of screening and prevention of dysmetabolism-related liver diseases, despite outwardly healthy biomarkers profile. Fatty liver disease is caused by the accumulation of fat into the liver and it is associated to increased risk of chronic diseases. Diagnosis of fatty liver is based on biopsy or ultrasound assessment but when these procedures are not available or feasible also some non-invasive scores have been showed to be reliable measures of this condition. In this study we compared the use of ultrasound and non-invasive scores to assess liver steatosis and associated metabolic disease, finding that Fatty Liver Index (FLI) is the best score for these diagnosis. Surprisingly, in women FLI cut-off value is 50% lower than in men, suggesting that different sex-specific factors may come into play in the development and evolution of liver steatosis. Thus, we suggest the need of a sex-specific personalized program of screening and prevention of dysmetabolism-related liver diseases. Simple non-invasive tests (NITs) have been proposed to assess liver steatosis and fibrosis but have not been validated for MASLD, a disease that shows different features and prevalence in the two sexes; We show here that Fatty liver Index (FLI) is the best NIT for predicting MASLD and that its cut-off value is 50% lower in women than in men; We suggest the need of a sex-specific personalized program of screening and prevention of dysmetabolism-related liver diseases, despite outwardly healthy biomarkers profile.