Context No universal waist circumference (WC) percentile cutoffs used have been proposed for screening central obesity in children and adolescents. Objective To develop international WC percentile cutoffs for children and adolescents with normal weight based on data from 8 countries in different global regions and to examine the relation with cardiovascular risk. Design and Setting We used pooled data on WC in 113,453 children and adolescents (males 50.2%) aged 4 to 20 years from 8 countries in different regions (Bulgaria, China, Iran, Korea, Malaysia, Poland, Seychelles, and Switzerland). We calculated WC percentile cutoffs in samples including or excluding children with obesity, overweight, or underweight. WC percentiles were generated using the general additive model for location, scale, and shape (GAMLSS). We also estimated the predictive power of the WC 90th percentile cutoffs to predict cardiovascular risk using receiver operator characteristics curve analysis based on data from 3 countries that had available data (China, Iran, and Korea). We also examined which WC percentiles linked with WC cutoffs for central obesity in adults (at age of 18 years). Main Outcome Measure WC measured based on recommendation by the World Health Organization. Results We validated the performance of the age- and sex-specific 90th percentile WC cutoffs calculated in children and adolescents (6-18 years of age) with normal weight (excluding youth with obesity, overweight, or underweight) by linking the percentile with cardiovascular risk (area under the curve [AUC]: 0.69 for boys; 0.63 for girls). In addition, WC percentile among normal weight children linked relatively well with established WC cutoffs for central obesity in adults (eg, AUC in US adolescents: 0.71 for boys; 0.68 for girls). Conclusion The international WC cutoffs developed in this study could be useful to screen central obesity in children and adolescents aged 6 to 18 years and allow direct comparison of WC distributions between populations and over time.

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The objectives of the current study, that is the first of its kind, were to determine the prevalence of the hypertriglyceridemic waist (HW) phenotype in a nationally representative sample of children, as well as the metabolic risk factors identified by HW, and to identify lifestyle habits related to this phenotype. This national survey was conducted on 4811 representative school-students. We assessed the sensitivity and specificity of the HW phenotype for abnormal anthropometric and biochemical factors by using receiver operator characteristic curves. We determined the association of dietary patterns (obtained by factor analysis), physical activity level and some environmental factors with the HW phenotype. Overall, 8.52% of participants had the HW phenotype. Those children with the HW phenotype were more likely to have cardiovascular risk factors, notably for overweight and hypercholesterolemia. The dietary pattern characterized by junk foods increased the odds of having the HW phenotype, OR = 1.426 (95%CI, 1.109, 1.892), whereas the other dietary pattern including healthy foods decreased this odds, OR = 0.874 (95%CI, 0.765, 0.998). The risk of the HW phenotype rose with the consumption of solid hydrogenated fat as well as white-flour bread. Low education of parents and a positive family history of diabetes mellitus, obesity and or premature cardiovascular disease were the other risk factors for the HW phenotype. Low levels of physical activity significantly increased the risk of having the HW phenotype. The HW phenotype can be used as an accurate and easy tool for screening children at metabolic risk in population-based studies.

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