Cardio-metabolic risk screening among adolescents: understanding the utility of body mass index, waist circumference and waist to height ratio

Background: Few studies have assessed how well body mass index (BMI), waist circumference (WC), or waist to height ratio (WtHR) perform in identifying cardio-metabolic risk among youth. Objective: The objective of this study was to evaluate the utility of BMI and WC percentiles and WtHR to distinguish adolescents with and without cardio-metabolic risk. Methods: A cross-sectional analysis of data from 6097 adolescents aged 10-13 years who participated in the HEALTHY study was conducted. Receiver operating characteristic curves determined the discriminatory ability of BMI and WC percentiles and WtHR. Results: The discriminatory ability of BMI percentile was good (area under the curve [AUC] >= 0.80) for elevated insulin and clustering of >= 3 risk factors, with optimal cut-points of 96 and 95, respectively. BMI percentile performed poor to fair (AUC = 0.57-0.75) in identifying youth with the majority of individual risk factors examined (elevated glucose, total cholesterol, low-density lipoprotein, blood pressure, triglycerides and high-density lipoprotein). WC percentile and WtHR performed similarly to BMI percentile. Conclusions: The current definition of obesity among US children performs well at identifying adolescents with elevated insulin and a clustering of = 3 cardio-metabolic risk factors. Evidence does not support WC percentile or WtHR as superior screening tools compared with BMI percentile for identifying cardio-metabolic risk.