Joint association of body roundness index and HOMA-IR with risk of MASLD in Korean populations

BACKGROUND: As the global prevalence of obesity rises, the clinical focus is shifting from simple BMI to a systemic perspective that integrates body composition and metabolic health. This study evaluates the association between Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) and the combined influence of insulin resistance and obesity-related body shape indices. METHODS: Utilizing the KoGES cohort (n = 3,196), participants were categorized into four groups based on the median values of HOMA-IR and the Body Roundness Index (BRI). MASLD was defined by an HSI score > 36, at least one metabolic component, and controlled alcohol consumption (< 30 g/day for men, < 20 g/day for women). Cox proportional hazard regression was conducted to assess the risk across groups, including interaction and subgroup analyses to determine the independence of these markers. RESULTS: Both HOMA-IR and BRI were significant predictors of MASLD risk even when fully adjusted, with Hazard Ratios (HR) of 1.80 (95% CI: 1.52-2.12) and 2.33 (95% CI: 1.96-2.76), respectively. In the joint analysis, the group with both high HOMA-IR and high obesity-related body shape index (BRI) showed a 3.58-fold (95% CI: 2.84-4.51) increased risk compared to the reference group. Notably, no significant additive or multiplicative interactions were found, confirming that these two factors serve as independent and distinct predictive markers. CONCLUSIONS: Combining HOMA-IR with body shape-related obesity markers like BRI provides a more robust prediction of MASLD risk than individual indices. These findings suggest that integrated monitoring of metabolic and morphological profiles is essential for the early identification of high-risk populations.