Obesity is an important determinant of severity in newly defined metabolic dysfunction-associated fatty liver disease

Background: The recently proposed definition of metabolic dysfunction-associated fatty liver disease (MAFLD) is based on the co-existence of hepatic steatosis with other metabolic disorders, including obesity and metabolic risk abnormalities such as hyperglycemia, high blood pressure and dyslipidemia. This study aimed to assess MAFLD severity according to the presence of metabolic abnormalities and obesity. Methods: Using transient elastography, hepatic steatosis and fibrosis severity were assessed by measuring the controlled attenuation parameter and liver stiffness measurement. A total of 1163 patients with MAFLD were categorized into the following four groups according to metabolic risk abnormalities and obesity presence: non-obese without metabolic risk abnormality group (Group 1; reference group); non-obese with metabolic risk abnormality group (Group 2); obese without metabolic risk abnormality group (Group 3); and obese with metabolic risk abnormality group (Group 4). A multiple logistic regression analysis was performed to determine severe hepatic steatosis and fibrosis risk in each group in both unadjusted and adjusted models. Results: In the adjusted model, the odds ratios (ORs) [95% confidence interval (CI)] for severe hepatic steatosis in Groups 2, 3, and 4 were 1.07 (0.61-1.88), 2.43 (1.44-4.08), and 4.07 (2.56-6.48), respectively (P_trend < 0.001). For liver fibrosis, compared with Group 1, Group 2 showed no significant increases in OR, whereas Groups 3 and 4 (obese groups) showed significant increases (OR = 4.70, 95% CI: 1.24-17.82 and OR = 6.43, 95% CI: 1.88-22.02, respectively). Conclusions: Obesity, rather than metabolic abnormality, is the principal determinant of severe hepatic steatosis and fibrosis in patients with MAFLD.