Comparative Diagnostic Performance of Metabolic Scoring Indices for Ultrasonographic Hepatic Steatosis: Development...

Background/Objectives: Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly termed non-alcoholic fatty liver disease (NAFLD), is the most prevalent chronic liver condition globally, affecting one-quarter of the adult population. Non-invasive metabolic indices offer a pragmatic alternative to liver biopsy for population-level steatosis screening. We aimed to systematically compare the diagnostic performance of four widely used metabolic indices-TyG, LAP, FLI, and VAI-and to derive a novel composite score that demonstrably surpasses each constituent index. Methods: Retrospective cross-sectional study; 1204 consecutive adults undergoing abdominal ultrasonography at a single tertiary centre (study period: 2024-2025; data collection period: January-April 2026); steatosis graded 0-3 by certified radiologists; four metabolic indices retrieved from pre-calculated columns; novel composite score derived by binary logistic regression with 10-fold stratified cross-validation (stratified by binary outcome); AUROC with 1000-iteration bootstrap 95% CI; and pairwise comparisons by the DeLong method. Results: Of 1204 patients (mean age 42.3 ± 12.5 years; 73.3% male; 13.4% with diabetes), steatosis grades were: Grade 0, 185 (15.4%); Grade 1, 539 (44.8%); Grade 2, 311 (25.8%); and Grade 3, 169 (14.0%). For significant steatosis (Grade ≥ 2), TyG achieved AUROC 0.884 [0.863-0.904] and LAP 0.883 [0.862-0.901], while FLI showed only moderate performance. The novel composite score achieved AUROC 0.896 [0.870-0.920] for any steatosis and 0.922 [0.906-0.938] for significant steatosis, significantly outperforming all four individual indices (DeLong p = 0.004 vs. TyG; p = 0.002 vs. LAP; p < 0.001 vs. FLI; p < 0.001 vs. VAI). Youden-optimal performance: sensitivity 87.1%, specificity 86.0%, and Youden index 0.731. Conclusions: A 10-fold cross-validated logistic composite of four metabolic indices significantly outperforms each constituent index for ultrasonographic hepatic steatosis detection. The composite score may serve as a practical, non-invasive tool for steatosis risk stratification pending external validation.