The discriminatory ability of the body roundness index and body mass index for metabolic diseases in Korean adults: a comparative study

Abstract

OBJECTIVES: Obesity is a major risk factor for metabolic diseases; however, body mass index (BMI), the most widely used anthropometric indicator, inadequately reflects fat distribution. The body roundness index (BRI) has been proposed as a more precise measure of abdominal obesity.METHODS: Data from the 2007-2022 Korea National Health and Nutrition Examination Survey (KNHANES) were used. Discrimination for diabetes, hypertension, hypercholesterolemia, and metabolic syndrome was assessed by calculating the area under the receiver operating characteristic curve (AUROC) and estimating odds ratios (ORs).RESULTS: AUROC values ranged from 0.739 to 0.844 for BMI and 0.745 to 0.851 for BRI, with both indices demonstrating their highest performance for metabolic syndrome. BRI outperformed BMI for 3 metabolic diseases except hypertension, with the largest AUROC difference observed for diabetes (0.01). Quintile-based ORs showed stronger associations for BRI, indicating approximately 2-fold higher risks for diabetes and metabolic syndrome compared with BMI. Subgroup analyses identified the most pronounced differences for diabetes in female aged 45 years or older and for metabolic syndrome in male aged 45 years or older. For both indices, the risk associated with increasing quintiles was greater in the younger age group, especially among female under 45 years, in whom the risk of metabolic syndrome was markedly higher in the highest BRI quintile compared with the lowest quintile.CONCLUSIONS: BRI showed superior discriminatory power and stronger associations with metabolic diseases compared with BMI, suggesting that it may complement BMI as a useful screening indicator in clinical and public health settings.