Optimal cut-offs of BMI, waist circumference, and percentage body fat for predicting metabolic syndrome among Lebanese adults -

Abstract

Background: Obesity is considered a key determinant of a cluster of metabolic abnormalities namely MetS. Body Mass Index (BMI), Waist Circumference (WC), and Percentage Body Fat (percent BF) have been proposed as indices to assess obesity with various cut-off points developed to classify subjects into different levels of obesity (overweight, obese and severely obese). However, ethnic differences have been shown to affect the sensitivity and specificity of these indices. Objective: To derive cut-off points of obesity indices associated with an increased risk of metabolic syndrome among Lebanese adults, to show the percent agreement between the newly derived cut-off points and those proposed internationally, and to compare the power of BMI, WC and percent BF in predicting MetS. Methods: This study is a secondary analysis of data drawn from the National Nutrition and Non-Communicable Disease Risk Factor Survey conducted in Lebanon between 2008 and 2009. Survey participants ≥ 18 years of age with no chronic diseases were included in this analysis (n=314;146 men and 168 women). MetS was diagnosed using the definition proposed by the National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATPIII). Receiver Operating Characteristic curves (ROC) analysis was employed to derive cut-off points of BMI, WC, and percent BF associated with increased risk of MetS. Results: In the present study, BMI, WC, and percent BF had same predictive power to predict MetS as they had comparable AUCs in both genders. In men, the AUCs of BMI,WC, and percent BF were as follows: 0.763, 0.756, and 0.693. As for women, AUCs were 0.807, 0.820, and 0.810, respectively. Compared to the international cut-off points for BMI ≥ 30 kg- m2, the derived cut-off points of BMIs for men and women respectively were 27.6 and 28.4 kg-m2 with AUC of 0.76 and 0.80. As for WC, the derived cut-offs were 96.7cm and 90.1 cm with AUC of 0.75 and 0.82, respectively, as compared to the international WC cut-off points of ≥ 102 cm in men and ≥ 88 cm in wome