Background and Aim: Metabolic dysfunction-associated steatotic liver disease (MASLD) has been used to rename nonalcoholic fatty liver disease (NAFLD). Given the changes in definitions, there has been concerns if both diseases are identical and whether the evidence generated under NAFLD can still be used for MASLD. Using our NAFLD Database, our aim was to evaluate which proportion of patients with NAFLD also fulfil the criteria for MASLD and whether this would affect the performance of common non-invasive tests (NITs).

Methods: The NAFLD database includes data collected from patients with an established diagnosis of NAFLD or NASH. In this study, the database was used to apply the definition of MASLD or MASH (defined as NAFLD or NASH plus at least one cardio-metabolic risk factor such as BMI>25, waist circumference ≥94/80cm, or type 2 diabetes (T2D), hypertension, or hyperlipidemia). We calculated the concordance of definitions for MASH and NASH or NAFLD and MASLD and determined if the new definitions influenced the NIT thresholds for FIB-4 and Enhanced Liver Fibrosis (ELF) test.

Results: There were 11,552 NAFLD patients in the NAFLD database with sufficient data to evaluate the presence of MASLD. The average age was 53 ± 12 years, 45% male, BMI 34.2 ± 8.2, and T2D 45%. Of these, 47% were enrolled in the USA/Canada, 16% in Middle East and North Africa (MENA), 15% in Europe, 15%in Southeast Asia, 4% in Latin America and the Caribbean, and <2% in other regions. Of the entire NAFLD group, 97.4% fulfilled the criteria for MASLD. In fact, 91.7% of NAFLD patients met the MASLD definition based on BMI alone (BMI>25). Among participants with NASH, 99.97% met the definition of MASH. Across different regions of the world, the concordance of NAFLD and MASLD was 98.8% in Europe and MENA, 99.6% in Latin America, 99.1% in USA/Canada, and 90.0% in Southeast Asia. Among subjects who had NITs and liver biopsy data available (n=4675), the predictive accuracy of ELF and FIB-4 for significant (stage≥2) and advanced (stage≥3) fibrosis were identical between MASLD and NAFLD classifications.

Conclusions: More than 97% of NAFLD patients have at least one cardio-metabolic risk factor allowing them to meet the criteria for MASLD. As a result, the clinical profile and NIT thresholds for FIB-4 and ELF are nearly identical between NAFLD/NASH and MASLD/MASH. These data provide evidence that NAFLD and MASLD can be used interchangeably.

Andrei Racila

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