TRI-PONDERAL MASS INDEX IS USEFUL FOR SCREENING CHILDREN AND ADOLESCENTS WITH INSULIN RESISTANCE.

OBJECTIVE: To investigate whether tri-ponderal mass index and body mass index Z scores are equivalent for screening children and adolescents with insulin resistance. METHODS: Cross-sectional study with 296 children and adolescents enrolled at public schools of Vitória, Espírito Santo, Brazil, aged eight to 14 years. The tri-ponderal mass index was calculated as the ratio between weight and height cubed. The body mass index was calculated as the ratio between weight and height squared. Insulin resistance was defined with the homeostatic model assessment (HOMA-IR). RESULTS: The HOMA-IR was higher in the 4th quartile of body mass index Z scores and tri-ponderal mass index compared to 1st and 2nd quartiles for both girls and boys. The areas under the age-adjusted receiver operating characteristic curves were similar between the indices for girls (body mass index Z scores=0.756; tri-ponderal mass index=0.763) and boys (body mass index Z scores=0.831; tri-ponderal mass index=0.843). In addition, according to the simple linear regression analyses estimations, both body mass index Z scores and tri-ponderal mass index explained a significant fraction of the homeostatic model assessment variability for girls (body mass index Z scores: R2=0.269; tri-ponderal mass index: R2=0.289; p<0.001) and boys (body mass index Z scores: R2=0.175; tri-ponderal mass index: R2=0.210; p<0.001). CONCLUSIONS: The tri-ponderal mass index and body mass index Z scores were similar to discriminate children and adolescents with insulin resistance. It is noteworthy that the use of tri-ponderal mass index is clearly advantageous, because it can be calculated with no concerns on adjustments for the age, a fact that makes it very applicable in the clinical practice.

Tri-ponderal mass index is useful for screening children and adolescents with insulin resistance / O índice de massa tri-ponderal é útil na triagem de crianças e adolescentes com resistência à insulina

ABSTRACT Objective: To investigate whether tri-ponderal mass index and body mass index Z scores are equivalent for screening children and adolescents with insulin resistance. Methods: Cross-sectional study with 296 children and adolescents enrolled at public schools of Vitória, Espírito Santo, Brazil, aged eight to 14 years. The tri-ponderal mass index was calculated as the ratio between weight and height cubed. The body mass index was calculated as the ratio between weight and height squared. Insulin resistance was defined with the homeostatic model assessment (HOMA-IR). Results: The HOMA-IR was higher in the 4th quartile of body mass index Z scores and tri-ponderal mass index compared to 1st and 2nd quartiles for both girls and boys. The areas under the age-adjusted receiver operating characteristic curves were similar between the indices for girls (body mass index Z scores=0.756; tri-ponderal mass index=0.763) and boys (body mass index Z scores=0.831; tri-ponderal mass index=0.843). In addition, according to the simple linear regression analyses estimations, both body mass index Z scores and tri-ponderal mass index explained a significant fraction of the homeostatic model assessment variability for girls (body mass index Z scores: R2=0.269; tri-ponderal mass index: R2=0.289; p<0.001) and boys (body mass index Z scores: R2=0.175; tri-ponderal mass index: R2=0.210; p<0.001). Conclusions: The tri-ponderal mass index and body mass index Z scores were similar to discriminate children and adolescents with insulin resistance. It is noteworthy that the use of tri-ponderal mass index is clearly advantageous, because it can be calculated with no concerns on adjustments for the age, a fact that makes it very applicable in the clinical practice.

RESUMO Objetivo: Investigar se o índice de massa tri-ponderal e os escores-z do índice de massa corporal são equivalentes na triagem de crianças e adolescentes com resistência à insulina. Métodos: Estudo transversal com 296 crianças e adolescentes matriculados em escolas públicas de Vitória, Espírito Santo, Brasil, com idades entre oito e 14 anos. O índice de massa tri-ponderal foi calculado como a razão entre o peso e a altura ao cubo. O índice de massa corporal foi calculado como a razão entre o peso e a altura ao quadrado. A resistência à insulina foi definida pelo modelo de avaliação da homeostase para resistência à insulina (HOMA-IR). Resultados: O HOMA-IR foi maior no 4º quartil dos escores-z do índice de massa corporal e do índice de massa tri-ponderal, em relação ao 1º e 2º quartis em ambos os sexos. As áreas sob as curvas receiver operating characteristic ajustadas por idade foram semelhantes em meninas (escores-z do índice de massa corporal=0,756; índice de massa tri-ponderal=0,763) e meninos (escores-z do índice de massa corporal=0,831; índice de massa tri-ponderal=0,843). Além disso, de acordo com as estimativas das análises de regressão linear simples, os escores-z do índice de massa corporal e o índice de massa tri-ponderal explicaram uma fração significativa da variabilidade do modelo de avaliação da homeostase para meninas (escores-z do índice de massa corporal: R2=0,269; índice de massa tri-ponderal: R2=0,289; p<0,001) e meninos (escores-z do índice de massa corporal: R2=0,175; índice de massa tri-ponderal: R2=0,210; p<0,001). Conclusões: O índice de massa tri-ponderal e os escores-z do índice de massa corporal foram semelhantes na triagem de crianças e adolescentes com resistência à insulina. É importante ressaltar que o uso do índice de massa tri-ponderal é claramente vantajoso, pois pode ser calculado sem ajustes por idade, fato que o torna muito aplicável à prática clínica.

Waist-to-height ratio is as reliable as biochemical markers to discriminate pediatric insulin resistance / A razão cintura/estatura é tão confiável quanto marcadores bioquímicos para discriminar resistência à insulina

Abstract Objective: Given the importance of incorporating simple and low-cost tools into the pediatric clinical setting to provide screening for insulin resistance, the present study sought to investigate whether waist-to-height ratio is comparable to biochemical markers for the discrimination of insulin resistance in children and adolescents. Methods: This cross-sectional study involved students from nine public schools. In total, 296 children and adolescents of both sexes, aged 8 -14 years, composed the sample. Waist-to-height ratio, triglycerides/glucose index, and triglycerides-to-HDL-C ratio were determined according to standard protocols. Insulin resistance was defined as homeostatic model assessment for insulin resistance with cut-off point ≥ 3.16. Results: Age, body mass index, frequency of overweight, waist circumference, waist-to-height ratio, insulin, glucose, homeostatic model assessment for insulin resistance, triglycerides, triglycerides/glucose index, and triglycerides-to-HDL-C were higher among insulin resistant boys and girls. Moderate correlation of all indicators (waist-to-height ratio, triglycerides/glucose index, and triglycerides-to-HDL-C ratio) with homeostatic model assessment for insulin resistance was observed for both sexes. The areas under the receiver operational characteristic curves ware similar between waist-to-height ratio and biochemical markers. Conclusion: The indicators provided similar discriminatory power for insulin resistance. However, taking into account the cost-benefit ratio, we suggest that waist-to-height ratio may be a useful tool to provide screening for insulin resistance in pediatric populations.

Resumo Objetivo: Considerando a importância de incorporar ferramentas simples e de baixo custo no cenário clínico-pediátrico para a triagem de resistência à insulina, o presente estudo buscou investigar se a razão cintura/estatura é comparável a marcadores bioquímicos na discriminação de resistência à insulina em crianças e adolescentes. Métodos: Este estudo transversal envolveu estudantes de nove escolas públicas. No total, 296 crianças e adolescentes, de ambos os sexos, com idades entre 8 e 14 anos, compuseram a amostra. A razão cintura/estatura, o índice triglicerídeos/glicose e a razão triglicerídeos/HDL-C foram determinados de acordo com protocolos padrão. A resistência à insulina foi definida por meio do modelo de avaliação homeostática para resistência insulínica, com ponto de corte ≥ 3.16. Resultados: Idade, índice de massa corporal, frequência de excesso de peso, circunferência da cintura, razão cintura/estatura, insulina, glicemia, modelo de avaliação homeostática para resistência insulínica, triglicerídeos, índice triglicerídeos/glicose e razão triglicerídeos/HDL-C foram maiores entre meninos e meninas com resistência à insulina. Também foram observadas, em ambos os sexos, correlações moderadas de todos os indicadores (razão cintura/estatura, índice triglicerídeos/glicose e razão triglicerídeos/HDL-C) com o modelo de avaliação homeostática para resistência à insulina. As áreas sob as curvas ROC foram semelhantes entre a razão cintura/estatura e os marcadores bioquímicos. Conclusão: Os indicadores forneceram poder discriminatório similar para a resistência à insulina. No entanto, levando em conta o custo-benefício, sugerimos que a razão cintura/estatura pode ser uma ferramenta útil para a triagem de resistência à insulina em populações pediátricas.

Ponderal index classifies obesity in children and adolescents more accurately than body mass index z-scores.

BACKGROUND: We aimed to compare the accuracy of the ponderal index (PI) vs. BMI-for-age z-scores transformed (BMIz) in estimating body fat levels and classifying obesity in children and adolescents from a Brazilian urban population. METHODS: This is a cross-sectional study with 1149 participants (53.2% male), aged 6 to 18 years. Body fat percent (BFP) was obtained by multi-frequency bioelectrical impedance. Non-linear regression analysis provided the accuracy of both BMIz and PI in estimating BFP. False positive rate was obtained from the proportion of individuals placed at or above the 95th percentile for BMIz or PI, whereas their BFP was discordantly below the 95th percentile. RESULTS: PI and BMIz appeared with similar stability from childhood to adolescence for both boys and girls. The portion of the variability in BFP explained by BMIz (R2 = 0.74 and R2 = 0.75) was close to the variability in BFP explained by PI (R2 = 0.73 and R2 = 0.75) for boys and girls, respectively. False positive rate was higher for BMIz compared with PI among boys (21.8% vs. 3.9%) and girls (28.5% vs. 17.5%). CONCLUSIONS: PI is a promising index for replacing BMIz in children and adolescents due to its potential to reduce false diagnosis of obesity.

Waist-to-height ratio is as reliable as biochemical markers to discriminate pediatric insulin resistance.

OBJECTIVE: Given the importance of incorporating simple and low-cost tools into the pediatric clinical setting to provide screening for insulin resistance, the present study sought to investigate whether waist-to-height ratio is comparable to biochemical markers for the discrimination of insulin resistance in children and adolescents. METHODS: This cross-sectional study involved students from nine public schools. In total, 296 children and adolescents of both sexes, aged 8-14 years, composed the sample. Waist-to-height ratio, triglycerides/glucose index, and triglycerides-to-HDL-C ratio were determined according to standard protocols. Insulin resistance was defined as homeostatic model assessment for insulin resistance with cut-off point ≥ 3.16. RESULTS: Age, body mass index, frequency of overweight, waist circumference, waist-to-height ratio, insulin, glucose, homeostatic model assessment for insulin resistance, triglycerides, triglycerides/glucose index, and triglycerides-to-HDL-C were higher among insulin resistant boys and girls. Moderate correlation of all indicators (waist-to-height ratio, triglycerides/glucose index, and triglycerides-to-HDL-C ratio) with homeostatic model assessment for insulin resistance was observed for both sexes. The areas under the receiver operational characteristic curves ware similar between waist-to-height ratio and biochemical markers. CONCLUSION: The indicators provided similar discriminatory power for insulin resistance. However, taking into account the cost-benefit ratio, we suggest that waist-to-height ratio may be a useful tool to provide screening for insulin resistance in pediatric populations.

Variáveis antropométricas e de composição corporal como preditores de risco cardiovascular e da síndrome metabólica em adolescentes / Anthropometric and body composition variables as predictors of cardiovascular risk and metabolic syndrome in adolescents

Introdução: Na triagem de indivíduos em risco de desenvolvimento de fatores de risco cardiovasculares e da síndrome metabólica, a antropometria surge como uma alternativa ao Índice de Massa Corporal (IMC), que pode ser utilizada para avaliar a composição corporal e perímetros. Assim, objetivou-se verificar a capacidade das medidas antropométricas, principalmente o perímetro do pescoço (PP) em predizer fatores de risco cardiovascular e síndrome metabólica em adolescentes. Método: Coletaram-se dados referentes à glicemia, colesterol total e frações, triglicerídeos e pressão arterial em 85 adolescentes de 11 a 15 anos, de escolas públicas de Alegre (ES). O percentual de gordura corporal (%GC) foi avaliado pela bioimpedância vertical bipolar. Resultados: Com base na curva ROC, as variáveis antropométricas perímetro do pescoço (PP), PC, IMC e %GC demonstraram ser eficazes no diagnóstico da síndrome metabólica, principalmente o PP. Quanto ao estado nutricional, 76%, 21% e 30%, respectivamente, apresentaram eutrofia, excesso de peso e alto %GC. O %GC, o perímetro da cintura (PC) e relação cintura-estatura (RCE) apresentaram valores mais elevados no sexo feminino em relação ao masculino. O colesterol total foi o que apresentou maior percentual de inadequação (37%), seguido dos triglicerídeos (18%). A prevalência geral da síndrome metabólica foi de 2,35%, sendo observada somente no sexo masculino (6,25%). Conclusão: O PP, o IMC, o %GC, o PC e a RCE são bons preditores de alterações metabólicas em adolescentes. Assim, essas medidas devem ser usadas em conjunto na avaliação nutricional deste grupo.(AU)

Introduction: In the screening of individuals at risk of developing cardiovascular risk factors and metabolic syndrome, anthropometry emerges as an alternative to the Body Mass Index (BMI), which can be used to evaluate body composition and perimeters, the ability of anthropometric measures, especially the neck circumference (PP) to predict cardiovascular risk factors and metabolic syndrome in adolescents, was verified. Methods: Data on glycemia, total cholesterol and fractions, triglycerides and blood pressure were collected from 85 adolescents aged 11 to 15 from public schools in Alegre (ES). The percentage of body fat (%GC) was evaluated by bipolar vertical bioimpedance. Results: Based on the ROC curve the anthropometric variables perimeter of the neck (CP), PC, BMI and %GC were shown to be effective in the diagnosis of the metabolic syndrome, mainly PP. Regarding nutritional status, 76%, 21% and 30%, respectively, presented eutrophy, excess weight and high% GC. The %GC, waist circumference (PC) and waist-to-height ratio (RCE) were higher in females than in males. Total cholesterol presented the highest percentage of inadequacy (37%), followed by triglycerides (18%). The overall prevalence of the metabolic syndrome was 2.35%, being observed only in the male sex (6.25%). Conclusion: PP, BMI, %GC, PC and CER are good predictors of metabolic changes in adolescents, so these measures should be used together in the nutritional assessment of this group.(AU)