Body Roundness Index and Waist-to-Height Ratio are Strongly Associated With Non-Alcoholic Fatty Liver Disease: A Population-Based Study

BACKGROUND A strong association between obesity and non-alcoholic fatty liver disease (NAFLD) has been reported. OBJECTIVES This study was conducted to evaluate if new obesity indices, including a body shape index (ABSI) and body roundness index (BRI), have stronger associations with NAFLD than waist-to-hip ratio (WHR) and waist-to-height ratio (WHtR). METHODS In this cross-sectional study, we utilized the data of 4,872 participants aged 18 - 74 years from a cohort study conducted among 6,143 subjects in northern Iran. Logistic regression analysis was performed on NAFLD as the outcome and obesity measures (based on Z-score values) as potential predictors. Receiver operating characteristic (ROC) analyses were conducted, in which NAFLD was considered as a reference variable and obesity measures as classification variables. The discriminatory ability of the obesity measures was reported based on area-under-the-curves, and the related cut-off points of BRI and WHtR were determined using the Youden index (YI). RESULTS Based on our results, BRI (OR = 5.484 for men and OR = 3.482 for women) and WHtR (OR = 5.309 for men and OR = 3.854 for women) showed a higher association with NAFLD than ABSI (OR = 1.363 for men and OR = 1.003 for women) and WHR (OR = 3.123 for men and OR = 1.628 for women). The optimal cut-off points for BRI were 4.00 (sensitivity = 82.7%, specificity = 70.8%) for men and 5.00 (sensitivity = 83.3%, specificity = 71.7%) for women. The optimal cut-off points for WHtR were 0.533 (sensitivity = 82.7%, specificity = 70.8%) for men and 0.580 (sensitivity = 83.3%, specificity = 71.7%) for women. CONCLUSIONS While BRI and WHtR have equally strong associations with NAFLD, ABSI and WHR have weaker associations with NAFLD than BRI and WHtR.