Differential associations of traditional and shape-based adiposity indices with steatosis and fibrosis risk in metabolic dysfunction-associated steatotic liver disease

Background: Traditional anthropometric indices reflect total body adiposity, whereas novel shape-based indices capture fat distribution and unfavorable adiposity. How these measures relate to hepatic steatosis and fibrosis risk across the spectrum of metabolic dysfunction-associated steatotic liver disease (MASLD) remains unclear. Methods: In this cross-sectional study, 222 patients with MASLD were included. Body mass index (BMI), waist circumference (WC), a body shape index (ABSI) and body roundness index (BRI) were evaluated. Hepatic steatosis was assessed by ultrasonography using the Bright Liver Echo Pattern (BLEP), while fibrosis risk was estimated using the Fibrosis-4 (FIB-4) index. Results: BMI, WC, and BRI were higher in individuals with moderate-to-severe hepatic steatosis (BLEP ≥ 2), whereas ABSI did not differ according to steatosis severity. In multivariable logistic regression, BMI was independently associated with BLEP ≥ 2 (OR 1.19; 95% CI 1.05-1.35; p = 0.006), together with fasting glucose. ABSI showed a positive correlation with FIB-4 (r = 0.248; p < 0.001), whereas BMI did not. In multivariable linear regression, ABSI remained independently associated with FIB-4 (β = 0.145; p = 0.017), while BMI and BRI were not. Receiver operating characteristic analyses showed that BMI and WC best discriminated moderate-to-severe steatosis, whereas ABSI demonstrated the highest accuracy for identifying advanced fibrosis risk (FIB-4 ≥ 2.67; AUC 0.714; p = 0.004). Conclusions: Traditional and shape-based anthropometric indices capture complementary aspects of MASLD. Integrating measures of total adiposity and body shape may improve risk stratification in MASLD, although findings require confirmation using direct measures of liver fibrosis.