Discrepancies between Nonalcoholic and Metabolic-associated Fatty Liver Disease by Multiple Steatosis Assessment

BACKGROUND AND AIMS: The redefinition of metabolic-associated fatty liver disease (MAFLD) from nonalcoholic fatty liver disease (NAFLD) has caused a revolution in clinical practice, and the characteristics of patients with steatosis but not MAFLD remain unclear. The aims were to compare the diagnosis rate of MAFLD in NAFLD using different steatosis methods and explore the features of non-MAFLD–NAFLD and MAFLD–non-NAFLD. METHODS: A cross-sectional study enrolling consecutive individuals was conducted at three medical centers in southern China from January 2015 to September 2020. Steatosis was evaluated by liver biopsy or magnetic resonance imaging-based proton density fat fraction (MRI-PDFF), ultrasound, controlled attenuation parameter (CAP), and fatty liver index (FLI). Fibrosis was assessed by the NAFLD fibrosis score, transient elastography, or shear wave elastography. RESULTS: The study enrolled 14,985 Chinese adults. The agreement of MAFLD and NAFLD diagnoses were 83% for FLI, 95% for ultrasound, 94% for both CAP and MRI-PDFF, and 95% for liver biopsy. The body mass index, blood pressure and lipid levels among non-MAFLD–NAFLD patients were similar metabolic parameters (p>0.05 for all), but not the alanine aminotransferase and the proportion of patients with insulin resistance, which were significantly higher in non-MAFLD–NAFLD with significant fibrosis. CONCLUSIONS: The new MAFLD definition ruled out 5–17% of NAFLD cases. NAFLD and MAFLD–NAFLD involved more severe metabolic abnormalities than MAFLD and MAFLD–non-NAFLD. Non-MAFLD–NAFLD patients with significant fibrosis had more severe liver injury and increased glycemic dysregulation within the normal range. Attention should be paid to its progression.