Abstract Objective Children with spina bifida (SB) are at risk for stunting and overweight. However, height and Body Mass Index (BMI) z-score distribution in children and adolescents with SB are unclear. The aim of this study was to examine height and BMI z-score distribution in Brazilian children and adolescents with and without SB. This study further aimed to examine whether height and BMI z-scores differ between individuals with and without SB. Method This study included 101 participants (SB: n= 18; non-SB: n= 83, aged 7-16 years). The World Health Organization (WHO) AnthroPlus software was used to calculate height and BMI z-scores. AnthroPlus z-score distribution graphs were used to examine individual z-scores based on the 2007 WHO normal distribution curve. Effects of the group (SB vs non-SB) on height and BMI z-scores were examined with sequential regression. Results In the WHO distribution graph analysis, height z-scores of participants with SB were slightly left-shifted compared to the WHO normal distribution curve. In the regression analysis, group (SB vs non-SB) was a significant predictor of height z-scores after controlling for sex and age (ΔR2= 0.064, p= 0.010). BMI z-scores of participants with SB were right-shifted compared to the WHO normal curve. However, there was no contribution of the group to BMI z-scores (ΔR2= 0.011, p= 0.301). Conclusions These findings suggest that Brazilian children and adolescents with SB may be at risk for reduced height and increased BMI.

Abstract Objective Population-level monitoring of body composition requires accurate, biologically-relevant, yet feasible methods for estimating percent body fat (%BF). The aim of this study was to develop and cross-validate an equation for %BF from Body Mass Index (BMI), age, and sex among children with intellectual disability (ID). This study further aimed to examine the performance of an existing BMI-based equation (Deurenberg equation) for %BF in children with ID. Method Participants were 107 children (63 boys; aged 6-15 years) with ID randomly allocated to development (n= 81) and cross-validation (n= 26) samples. Dual-Energy X-Ray Absorptiometry provided the criterion %BF. Results The model including BMI, age, and sex (0 = male; 1 = female) had a significant goodness-of-fit in determining %BF (p< 0.001; R2= 0.69; SEE =5.68%). The equation was: %BF = - 15.416 + (1.394 × BMI) + (4.538 × age) - (0.262 × age2) + (5.489 × sex). The equation was cross-validated in the separate sample based on (i) strong correlation (r = 0.82; p< 0.001) and non-significant differences between actual and predicted %BF (28.6 ± 9.6% and 30.1 ± 7.1%, respectively); (ii) mean absolute error (MAE) = 4.4%; and (iii) reasonable %BF estimations in Bland-Altman plot (mean: 1.48%; 95% CI: 12.5, -9.6). The Deurenberg equation had a large %BF underestimation (mean: -7.1%; 95% CI: 5.3, -19.5), significant difference between actual and estimated %BF (28.6 ± 9.7% and 21.5 ± 7.0%, respectively; p< 0.001), and MAE = 8.1%. Conclusions The developed equation with BMI, sex, and age provides valid %BF estimates for facilitating population-level body fat screening among children with ID.

Resumo: Objetivo: Desenvolver curvas específicas de índice de massa corporal (IMC-para-idade) para população brasileira com síndrome de Down (SD). O objetivo secundário foi comparar os valores de IMC-para-idade com os valores normativos dos Centros de Controle e Prevenção de Doenças dos Estados Unidos (CDC). Métodos: Estudo do tipo retrospectivo e transversal. A amostra foi constituída de 706 jovens com SD (56,7%, meninos) recrutados em 51 instituições no Estado de São Paulo, Brasil. Peso e estatura foram obtidos e empregados para o cálculo de IMC (Kg/m2). O método LMS foi usado para a construção das curvas. Escores Z foram calculados com base na referência do CDC 2000. Resultados: As curvas de referência de IMC-para-idade para meninos e meninas com SD na faixa entre 2-18 anos apresentaram excelente ajuste estatístico. Aos 2 anos, o escore Z médio IMC de crianças com SD apresentou-se menor quando comparado com o CDC (escore Z = -0,2). Em contraste, os escores Z médios de IMC de jovens com SD foram superiores entre 3-18 anos (escores Z = +0,2 a +1,3). Conclusões: A população brasileira com SD apresentou diferentes padrões de IMC quando comparada com as referências do CDC. As curvas desenvolvidas neste estudo representam a primeira referência nacional de IMC-para-idade para jovens com SD. Espera-se, portanto, que essas curvas possam guiar pais e profissionais na avaliação do estado nutricional de crianças e adolescentes com SD no território brasileiro.

Abstract: Objective: To develop Brazilian growth charts for body mass index (BMI-for-age) for individuals with Down syndrome (DS). The secondary objective was to compare the BMI-for-age with the Centers for Disease Control and Prevention standards (CDC). Methods: A retrospective and cross-sectional growth study of 706 youth with DS (56.7% males) was performed in 51 centers in São Paulo state, Brazil. Weight and height were used to calculate the BMI (kg/m2). The LMS method was applied to construct the growth charts. Z-scores were based on the CDC 2000 growth standards. Results: The BMI-for-age reference charts showed excellent goodness of fit statistics for boys and girls with DS aged 2-18 years. At 2 years of age, the mean BMI Z-scores of boys and girls with DS were lower compared to those of the CDC (Z-score = −0.2). In contrast, children with DS aged 3-18 years had higher mean Z-scores for BMI-for-age when compared to those of the CDC (Z-scores = +0.2 to +1.3). Conclusions: The BMI of Brazilian youth with DS differs from those references established by CDC. These are the first Brazilian BMI-for-age charts for individuals with DS and will hopefully guide clinicians and parents in the evaluation and management of the nutritional status in children and adolescents with DS in Brazil.

Introduction: Adolescents with Down syndrome (DS) show high rate of overweight and tend to accumulate high amount of fat compared to the same people without the syndrome. Objective: To estimate the cutoff point of the Body Mass Index (BMI) for the diagnosis of obesity in adolescents with DS according to different references for BMI in relation to the percentage of body fat (%BF) measured by dual-energy X-ray absorptiometry (DXA). Methods: The sample was composed of 34 adolescents with DS (aged: 10 to 17 years old). BMI was evaluated according to the references of the International Obesity Task Force (IOTF), the World Health Organization (WHO) for the general population, and Myrelid et al. and Styles et al. for people with DS. The %BF was assessed by whole body DXA and classified according to National Health And Nutrition Examination Survey (NHANES, 2011). Results: The boys were significantly taller than the girls and this %BF higher than boys. All references who have used BMI to assess obesity was positively associated with %BF measured by DXA in the diagnosis of obesity. Using the ROC curve in relation to %BF by DXA, all references showed high sensitivity, but the z-score of BMI by WHO showed better specificity, with the value of the accuracy of 0.82 for the cutoff point above 2.14. Conclusions: All the references used for the diagnosis of obesity were associated with %BF measured by DXA, and the cutoff point of z-scores above 2.14 by WHO showed better specificity.

Introducción: adolescentes con síndrome de Down (SD) muestran alta tasa de sobrepeso y tienden a acumular gran cantidad de grasa en comparación con los adolescentes sin el síndrome. Objetivo: estimar el punto de corte del índice de masa corporal (IMC) para el diagnóstico de obesidad en adolescentes con SD de acuerdo con las diferentes referencias para el IMC en relación con el porcentaje de grasa corporal (%GC) obtenido por el absorciometría con rayos X de doble energía (DXA). Métodos: la muestra se compone de 34 adolescentes con SD (10 a 17 años). El IMC se evaluó de acuerdo con las referencias de la International Obesity Task Force (IOTF), Organización Mundial de la Salud (OMS) para la población general, y Myrelid et al. y Estyles et al. para personas con SD. El %GC fue evaluado por DXA y clasificado según NHANES (2011). Resultados: los niños fueron significativamente más altos que las niñas, y estas con mayor %GC que los niños. Todas las referencias que han utilizado el IMC se asociaron positivamente con el %GC medido por DXA en el diagnóstico de la obesidad. Utilizando la curva ROC en relación con %GC por DXA todas las referencias mostraron alta sensibilidad, pero el score-z del IMC por la OMS mostró mejor especificidad, con el valor de exactitud de 0,82 para el punto de corte por encima de 2,14. Conclusiones: todas las referencias utilizadas para el diagnóstico de obesidad se asociaron con el %GC medido por DXA, y el punto de corte del score-z por encima de 2,14 por la OMS mostró mejor especificidad.