ABC | Volume 114, Nº3, March 2020

Original Article Waist Circumference Percentiles and Cut-Off Values for Obesity in a Large Sample of Students from 6 To 10 Years Old Of The São Paulo State, Brazil José Luiz F. Santos, 1 Valentin P. Valério, 1 Rafael N. Fernandes, 1 Ligia Duarte, 1 Antonio C. Assumpção, 1 Jayme Guerreiro, 1 Antonio L. Sickler, 1 Álvaro A. R. Lemos, 1 Jayro G. Goulart Filho, 1 Luiz Antonio Machado Cesar, 2 Ibraim Masciarelli Pinto, 3 Carlos Magalhães, 4 Maria Fernanda Hussid, 4 C leber Camacho, 4 Alvaro Avezum, 1 Carine T. Sangaleti, 5 F ernanda Marciano Consolim-Colombo 6 Sociedade de Cardiologia do Estado de São Paulo, 1 São Paulo, SP – Brazil Instituto do Coração (InCor) – Cardiopneumologia, 2 São Paulo, SP – Brazil Instituto Dante Pazzanese de Cardiologia – Cardiologia, 3 São Paulo, SP – Brazil Universidade Nove de Julho, 4 São Paulo, SP – Brazil Universidade Estadual do Centro-Oeste - Enfermagem, 5 Guarapuava, PR – Brazil Universidade de Sao Paulo Faculdade de Medicina Hospital das Clínicas Instituto do Coração, 6 São Paulo, SP – Brazil Mailing Address: Carine Sangaleti • Universidade Estadual do Centro-Oeste, 03. Postal Code 85015-430, Guarapuava, PR – Brazil E-mail: sangaleti@yahoo.com.br Manuscript received February 08, 2019, revised manuscript May 11, 2019, accepted June 18, 2019 DOI: https://doi.org/10.36660/abc.20190043 Abstract Backgroud: The prevalence of obesity has systematically been increased in the population, including children and adolescents, around the world. Objectives: To describe reference percentile curves for waist circumference (WC) in Brazilian children and provide cut‑off values of WC to identify children at risk for obesity. Methods: A multicenter, prospective, cross-sectional study was performed with children aged from 6 to 10 years old, enrolled in public and private elementary schools from 13 cities of the São Paulo State. Height, weight, andWC were measured in duplicate in 22,000 children (11,199 boys). To establish theWC best cut-off value for obesity diagnosis, ROC curves with children classified as normal weight and obese were calculated, according to BMI curves, stratified by gender and age, and the Youden Index was utilized as the maximum potential effectiveness of this biomarker. A p < 0.05 was considered statistically significant. Results: WC values increased with age in both boys and girls. The prevalence of obesity in each age group varied from 17% (6 years old) to 21.6% (9 years old) among boys, and from 14.1% (7 years old) to 17.3 % (9 years old) among girls. ROC analyses have shown the 75 th percentile as a cut-off for obesity risk, and the diagnosis of obesity is classified on the 85 th percentile or more. Conclusion: Age and gender specific reference curves of WC for Brazilian children and cut-off values for obesity risk may be used for national screening and interventional studies to reduce the obesity burden in Brazil. (Arq Bras Cardiol. 2020; 114(3):530-537) Keywords: Child; Waist Circunference/physiology; Obesity, Students; Parameters; Anthropometry. Introduction The worldwide prevalence of obesity, particularly among children, has been increasing exponentially . Over the last 30 years, several national surveys have recorded significant increment in the prevalence of obesity and overweight across Brazilian regions. 1 Childhood obesity is linked to the development of obesity in adults. Moreover, the obese child is exposed to a higher risk of developing type 2 diabetes, hypertension and vascular abnormalities, which are considered precursors of atherosclerosis in adulthood. Left ventricular hypertrophy and kidney problems have also been described in obese children. 2 The increased prevalence of obesity and the strong association with several comorbidities in children provide the relevance for public health. 3 As a result, it is necessary to find a simple anthropometric parameter that may be used to identify obese or at- risk- of- becoming obese children, which may contribute to the appropriate intervention tools to improve this trend. Obesity and overweight rates across population groups are typically based on body mass index (BMI). However, BMI does not reflect body composition, providing limited information on the central or abdominal adiposity. Waist circumference (WC) measurement is highly sensitive and quite effective in predicting visceral adiposity levels in the pediatric population. Indeed, WC values correlate with obesity-related metabolic disorders, including insulin resistance, dyslipidemia and 530