ABC | Volume 114, Nº3, March 2020

Original Article Santos et al. Waist circumference of children in Brazil Arq Bras Cardiol. 2020; 114(3):530-537 6 1.606 24.5 ± 5.85 1.20 ± 0.06 16.7 ± 2.83 58.8 ± 7.63 11.8 17 7 2.223 26.8 ± 6.76 1.25 ± 0.07 16.9 ± 3.14 60.5 ± 8.37 11.6 18.7 8 2.450 29.5 ± 7.81 1.30 ± 0.07 17.3 ± 3.41 62.1 ± 8.80 12.3 18.8 9 2.610 33.1 ± 9.06 1.35 ± 0.07 17.9 ± 3.70 64.4 ± 10.15 13.0 21.6 10 2.310 36.8 ± 10.37 1.40 ± 0.08 18.4 ± 3.92 67.2 ± 10.54 14.0 20.4 Total 11.199 6 1.612 24.2 ± 5.85 1.19 ± 0.06 16.7 ± 2.95 59 ± 7.95 13.6 15.0 7 2.236 26.0 ± 6.80 1.23 ± 0.06 16.8 ± 3.15 59.8 ± 8.43 12.2 14.1 8 2.284 29.2 ± 7.85 1.29 ± 0.07 17.2 ± 3.49 61.9 ± 9.16 13.5 16.6 9 2.502 32.8 ± 8.92 1.35 ± 0.07 17.8 ± 3.54 64.1 ± 9.75 15.6 17.3 10 2.252 36.9 ± 9.96 1.41 ± 0.08 18.3 ± 3.76 66.8 ± 10.19 14.8 15.7 Total 10.886 y: years old. Figure 1 shows the smoothed computedwaist circumference percentile curves for the 5 th , 10 th , 25 th , 50 th , 75 th , 85 th , 90 th and 95 th percentile for boys and girls. We analyzed the correlation between WC and anthropometric parameters. There was a strong correlation between WC and weight (r 2  = 0.77, p < 0.001) and WC and BMI (r 2  = 0.74, p < 0.001), and a weak correlation between WC and height (r 2  = 0.31, p < 0.001). The distribution of WC values in percentiles from 5 th to 95 th , according to age and gender, as well as the best sensitivity and specificity ROC cut-off values of WC, are shown in Table 2. The cut-off values for WC are slightly below or in the range of 75 th . Thus, for children with a WC classified into the 75 th percentile the presence of overweigth or obesity must be taken into account. Moreover, the diagnosis of obesity is cleary present in children with a WC classified in the 85 th percentile or higher. In this study, among the eutrophic children, fewer than 7% had a WC value indicating obesity. Among the children categorized as obese by BMI, almost 90%may be characterized as being obese simply by measuring the WC (Table 3). Figure 2 shows the graphic representation of the 50 th percentile values (cm) of the WC set in the current study along with the values obtained from publications of 12 different countries, for boys (A) and girls (B) aged from 6 to 10 years. We detected that six-year-old Brazilian boys had a WC similar to the Mexican boys, the highest of all countries. Seven- to nine-year-old Brazilian boys have WC values lower than those observed in Mexican and Indian boys, and at 10 the values were also lower than the USA boys. Six, seven and ten‑year‑old Brazilian girls had similar or slightly lower WC values than those detected in Mexican and Indian girls, and 8 and 9 year-old girls also had WC values lower than Mexican girls. Moreover, Figure 2 presents the 50% percentile of WC values of the Brazilian boys (C) and girls (D) and in a previous study published in 2007. It may be seen that the current WC 50 th percentile curves for Brazilian boys was higher than the values of 2007. The current WC 50 th percentile curves for Brazilian girls are much higher than the values obtained in 2007, around 2.0 cm at 7 and 8, 2.5 cm at 9 years old, and reaching 4.0 cm at 10 years old. Discussion This study presents age and gender specific WC percentile values for a large and representative sample of Brazilian children aged 6-10 years, based on a multicenter longitudinal anthropometric evaluation of school children. Furthermore, it is the first study to propose that WC cut-offs values are associated with obesity, according to BMI for boys and girls from 6 to ten years old. Besides, our study demonstrated that in this school population the prevalence of fat excess was around 30%, with 15% boys and girls overweight and another 15% already obese. Indeed, these findings corroborate previous data pointing out that childhood obesity is an increasingly serious health issue nationwide and worldwide. 42-44 These data complement the existing set of WC reference values obtained in some other countries and enhance the assessment capabilities of childhood obesity, in the most diverse sites for children care. Since several relationships may be established with the values of waist circumference, such as intra-abdominal fat deposition and cardiovascular disease risk factors in children, 45-48 waist circumference could be adopted as an alternative or additional measurement to BMI in children. The strong correlation found between circumference values and BMI in this study demonstrates that such replacement or its additional use is feasible. 532