Avaliação de diferentes referências de índice de massa corporal para adolescentes em função dos riscos cardiovasculares e da síndrome metabólica em Viçosa, MG
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2010-03-12
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Universidade Federal de Viçosa
Resumo
São uma necessidade e um desafio estudar as diversas referências de IMC existentes para adolescentes, em função das alterações metabólicas relacionadas a esta fase da vida, bem como as ocasionadas pelo excesso de peso. Objetivou-se avaliar diferentes referências de IMC, para adolescentes, em função dos riscos cardiovasculares e da síndrome metabólica (SM). Procedeu-se a um estudo transversal com 172 jovens de ambos os sexos, de 16 a 19 anos, selecionados em escolas públicas e particulares de Viçosa, MG, tendo como critérios de inclusão, a ocorrência da menarca há mais de um ano para as meninas e a presença de pelos axilares para os meninos. Foram feitas medidas de peso, estatura, circunferência da cintura (CC), calculado o IMC e razão cintura/estatura (RCE), percentual de gordura corporal (%GC), pressão arterial (parâmetro clínico) e avaliados os seguintes parâmetros bioquímicos: insulina de jejum, glicemia de jejum, triglicerídeos (TG), colesterol total (CT), HDL, LDL. Com os valores de insulina e glicemia de jejum, calculou-se a resistência insulínica (HOMA-IR). O estado nutricional foi classificado pelo IMC utilizando-se sete referências: Must et al. (1991); Himes e Dietz (1994); Anjos et al.(1998); IOTF (Cole et al., 2000) ; CDC (Kuczmarski et al., 2000); Conde e Monteiro (2006) e WHO (DE ONIS et al., 2007). O percentual de gordura corporal foi estimado utilizando-se o aparelho de bioimpedância elétrica tetrapolar horizontal. Este trabalho foi aprovado pelo Comitê de Ética em Pesquisa com Seres Humanos da Universidade Federal de Viçosa. Como resultado, foram encontrados valores maiores de CC e PAS nos meninos (p<0,05) e gordura corporal, CT, LDL e HDL nas meninas (p<0,05). No sexo feminino, as prevalências de valores indesejáveis de CT, LDL, HDL, TG e insulina foram de 60,0%, 34,0%, 16,0%, 10,0%, 6,0%, e nos meninos de 29,2%, 13,9%, 52,8%, 18,1% e 1,4%, respectivamente. Hiperglicemia ocorreu somente em 1,0% das meninas. Pressão arterial (PA) sistêmica elevada em 6,0% do sexo feminino e em 18,1% do masculino. Diferenças entre os sexos (p<0,05) foram encontradas nas prevalências de alterações para CT, LDL, HDL e PA. Identificou-se 4,0% do sexo feminino e 1,4% do masculino com CC acima da normalidade; 81,0% das meninas e 81,9% dos meninos apresentaram pelo menos um fator de risco cardiovascular, sem diferenças entre os sexos (p>0,05). Diagnosticou-se SM em 1,0% das meninas e 1,4% dos meninos. No sexo feminino, todas as medidas de localização de gordura (IMC, %GC, CC e RCE) se associaram positivamente com TG, HOMA-IR, PAS e PAD (p<0,05), estes dois últimos mais bem explicados pelo IMC, e os dois primeiros pela RCE. A CC e a RCE mantiveram associação positiva (p<0,05) com as alterações bioquímicas e clínica, todas independentes do % GC, mas não do IMC. No sexo masculino, houve associação positiva das medidas com HOMA-IR, PAS e LDL (p<0,05), com maior poder de explicação pela RCE. O efeito da CC se manteve positivo (p<0,05) para a PAS, sendo independente do %GC. Já a RCE, se manteve positiva e significantemente associada ao LDL, independentemente do %GC, ao TG, independentemente do IMC e ao HOMA-IR, independentemente da localização da gordura total. O uso de sete referências de IMC para o diagnóstico nutricional proporcionou variação no percentual de alterações para o excesso de peso de 6,0-12,0% no sexo feminino e de 8,3-20,8% no masculino, sendo que as maiores prevalências foram diagnosticadas pelas duas referências brasileiras. As prevalências de gordura corporal elevada foram de 42,0% nas meninas e de 8,3% nos meninos. Para o sexo feminino, todas as referências do IMC obtiveram baixa sensibilidade (<28,6%) e alta especificidade (100%) em detectá-las com alto percentual de gordura corporal; com melhor desempenho para a de Anjos et al. (1998); e, para o masculino, boa sensibilidade (>66,7%) e alta especificidade (>86,4%), sendo a do IOTF (Cole et al., 2000) e a da WHO (2007), as que obtiveram melhores resultados. As referências do IMC apresentaram de discreta a substancial concordância com o percentual de gordura corporal, com melhor desempenho nos meninos. Pelo IMC foi possível prever, entre os componentes da SM, níveis elevados de CC e TG no sexo feminino e PA no masculino, com as respectivas áreas sob a curva de 0,98; 0,74 e 0,70. Os melhores pontos de corte para esta amostra apresentaram altas sensibilidades (83,3%-100%) e especificidades regulares a altas (56,2%-97,9%) e variaram de 20,3kg/m² a 25,2kg/m², inferiores aos propostos nas referências estudadas, exceto para CC do sexo feminino. Pela referência do CDC (KUCZMARSKI et al., 2000) obteve-se a mesma sensibilidade, mas maiores especificidades do que as demais para o sexo feminino. Já no masculino, a referência de Anjos et al. (1998) obteve maior sensibilidade (33,3%) em detectar hipertensão arterial sistêmica e alta especificidade (81,7%). Os resultados mostraram que um número expressivo de adolescentes apresentou alterações nos parâmetros avaliados. A RCE foi a mais preditiva de efeitos adversos para o sistema cardiovascular, sendo interessante que seu diagnóstico seja feito em conjunto com o IMC. As referências do IMC demonstraram baixa sensibilidade em diagnosticar excesso de adiposidade no sexo feminino, assim como em detectar alterações metabólicas em ambos os sexos, ou seja, não apresentaram boa capacidade em identificar fatores de risco cardiovasculares e componentes da Síndrome Metabólica.
They have the need and the challenge of studying the various references to existing BMI for teenagers, according to the metabolic changes related to this phase of life, as well as those caused by overweight. The aim was to evaluate different references of BMI for teenagers, according to the risk of cardiovascular and metabolic syndrome (MS). We conducted a cross-sectional study with 172 young men and women from 16 to 19 years old, selected from public and private schools of Viçosa, MG, with the inclusion criteria, the occurrence of menarche for longer than one year for girls and presence of auxiliary hair in boys. Measurements were made of weight, height, waist circumference (WC), calculated BMI and waist/height ratio (WHR), percentage of body fat (% BF), blood pressure (clinical parameters) and assessed the following biochemical parameters: insulin fasting, fasting glucose, triglycerides (TG), total cholesterol (TC), HDL, LDL. Through the values of insulin and fasting glucose, we calculated insulin resistance (HOMA-IR). Nutritional status was classified by BMI using seven references: Must et al. (1991), Himes and Dietz (1994), Anjos et al. (1998), IOTF (Cole et al., 2000), CDC (Kuczmarski et al., 2000), Conde and Monteiro (2006) and WHO (DE ONIS et al., 2007). The percentage of body fat was estimated using the apparatus of horizontal tetrapolar bioelectrical impedance. This study was approved by the Ethics in Human Research, Federal University of Viçosa. As a result it was found higher values for WC and SBP in boys (p <0,05) and body fat, TC, LDL, and HDL in females (p <0,05). In females, the prevalence of undesirable values of TC, LDL, HDL, TG and insulin were 60,0%, 34,0%, 16,0%, 10,0%, 6,0%, and the boys 29,2%, 13,9%, 52,8%, 18,1% and 1,4% respectively. Hyperglycemia occurred in only 1,0% of girls. Blood pressure (BP) was elevated in 6,0% of females and 18,1% in males. Differences between the sexes (p <0,05) were found in the prevalence of changes for TC, LDL, HDL and BP. We identified 4,0% of females and 1,4% of males with WC above the normal range; 81,0% of girls and 81,9% of boys had at least one cardiovascular risk factor, with no differences between the sexes (p> 0,05). SM was diagnosed in 1,0% of girls and 1,4% of boys. In females, all measures of fat distribution (BMI, %BF, WC and WHR) are positively associated with TG, HOMA-IR, SBP and DBP (p <0,05), the latter two best explained by BMI, and the first two ones by the WHR. WC and WHR remained positive association (p <0,05) with biochemical and clinical changes, all independent on %BF, but not BMI. In males, there was a positive association between measures and HOMA-IR, SBP and LDL (p <0,05), with greater explanatory power of the WHR. The effect of WC remained positive (p <0,05) for SBP and is independent on %BF. The WHR, remained positively and significantly associated with LDL, independent on %BF, the TG independently on BMI and HOMA-IR independent on the location of total fat. The use of seven references BMI for nutritional status provided variation in the percentage of change for the overweight, 6,0-12,0% in female and 8,3-20,8% in males, with the highest prevalence were diagnosed by two Brazilian references. The prevalences of high body fat were 42,0% in girls and 8,3% in boys. For females, all references BMI showed low sensitivity (<28,6%) and high specificity (100%) in detecting them with a high body fat percentage, with better performance for the Anjos et al. (1998) and for male, good sensitivity (>66,7%) and high specificity (>86.4%), and the IOTF (Cole et al., 2000) and WHO (2007), who obtained the best results. References BMI presented with slight to substantial agreement with the percentage of body fat, with better performance in boys. BMI was possible to predict between the components of MS, high levels of WC and TG in female and PA in male, with their areas under the curve of 0,98, 0,74 and 0,70. The best cutoff points for this sample showed high sensitivity (83,3% - 100%) and regular high specificities (56,2% - 97,9%) and ranged from 20,3 kg/m² to 25,2 kg/m² lower than those proposed in references studied, except for CC women. The CDC reference (Kuczmarski et al., 2000) obtained the same sensitivity but higher specificity than the other for females. In the male, the reference Anjos et al. (1998) demonstrated the highest sensitivity (33,3%) in detecting hypertension and high specificity (81,7%). The results showed that significant number of adolescents showed disorders in the parameters. The WHR was the most predictive of adverse effects on the cardiovascular system, it is interesting that his diagnosis is done in conjunction with the BMI. References BMI showed low sensitivity to diagnose excess body fat in women, as well as to detect metabolic disorders in both genders, that means they didn t show a good ability to identify cardiovascular risk factors and components of metabolic syndrome.
They have the need and the challenge of studying the various references to existing BMI for teenagers, according to the metabolic changes related to this phase of life, as well as those caused by overweight. The aim was to evaluate different references of BMI for teenagers, according to the risk of cardiovascular and metabolic syndrome (MS). We conducted a cross-sectional study with 172 young men and women from 16 to 19 years old, selected from public and private schools of Viçosa, MG, with the inclusion criteria, the occurrence of menarche for longer than one year for girls and presence of auxiliary hair in boys. Measurements were made of weight, height, waist circumference (WC), calculated BMI and waist/height ratio (WHR), percentage of body fat (% BF), blood pressure (clinical parameters) and assessed the following biochemical parameters: insulin fasting, fasting glucose, triglycerides (TG), total cholesterol (TC), HDL, LDL. Through the values of insulin and fasting glucose, we calculated insulin resistance (HOMA-IR). Nutritional status was classified by BMI using seven references: Must et al. (1991), Himes and Dietz (1994), Anjos et al. (1998), IOTF (Cole et al., 2000), CDC (Kuczmarski et al., 2000), Conde and Monteiro (2006) and WHO (DE ONIS et al., 2007). The percentage of body fat was estimated using the apparatus of horizontal tetrapolar bioelectrical impedance. This study was approved by the Ethics in Human Research, Federal University of Viçosa. As a result it was found higher values for WC and SBP in boys (p <0,05) and body fat, TC, LDL, and HDL in females (p <0,05). In females, the prevalence of undesirable values of TC, LDL, HDL, TG and insulin were 60,0%, 34,0%, 16,0%, 10,0%, 6,0%, and the boys 29,2%, 13,9%, 52,8%, 18,1% and 1,4% respectively. Hyperglycemia occurred in only 1,0% of girls. Blood pressure (BP) was elevated in 6,0% of females and 18,1% in males. Differences between the sexes (p <0,05) were found in the prevalence of changes for TC, LDL, HDL and BP. We identified 4,0% of females and 1,4% of males with WC above the normal range; 81,0% of girls and 81,9% of boys had at least one cardiovascular risk factor, with no differences between the sexes (p> 0,05). SM was diagnosed in 1,0% of girls and 1,4% of boys. In females, all measures of fat distribution (BMI, %BF, WC and WHR) are positively associated with TG, HOMA-IR, SBP and DBP (p <0,05), the latter two best explained by BMI, and the first two ones by the WHR. WC and WHR remained positive association (p <0,05) with biochemical and clinical changes, all independent on %BF, but not BMI. In males, there was a positive association between measures and HOMA-IR, SBP and LDL (p <0,05), with greater explanatory power of the WHR. The effect of WC remained positive (p <0,05) for SBP and is independent on %BF. The WHR, remained positively and significantly associated with LDL, independent on %BF, the TG independently on BMI and HOMA-IR independent on the location of total fat. The use of seven references BMI for nutritional status provided variation in the percentage of change for the overweight, 6,0-12,0% in female and 8,3-20,8% in males, with the highest prevalence were diagnosed by two Brazilian references. The prevalences of high body fat were 42,0% in girls and 8,3% in boys. For females, all references BMI showed low sensitivity (<28,6%) and high specificity (100%) in detecting them with a high body fat percentage, with better performance for the Anjos et al. (1998) and for male, good sensitivity (>66,7%) and high specificity (>86.4%), and the IOTF (Cole et al., 2000) and WHO (2007), who obtained the best results. References BMI presented with slight to substantial agreement with the percentage of body fat, with better performance in boys. BMI was possible to predict between the components of MS, high levels of WC and TG in female and PA in male, with their areas under the curve of 0,98, 0,74 and 0,70. The best cutoff points for this sample showed high sensitivity (83,3% - 100%) and regular high specificities (56,2% - 97,9%) and ranged from 20,3 kg/m² to 25,2 kg/m² lower than those proposed in references studied, except for CC women. The CDC reference (Kuczmarski et al., 2000) obtained the same sensitivity but higher specificity than the other for females. In the male, the reference Anjos et al. (1998) demonstrated the highest sensitivity (33,3%) in detecting hypertension and high specificity (81,7%). The results showed that significant number of adolescents showed disorders in the parameters. The WHR was the most predictive of adverse effects on the cardiovascular system, it is interesting that his diagnosis is done in conjunction with the BMI. References BMI showed low sensitivity to diagnose excess body fat in women, as well as to detect metabolic disorders in both genders, that means they didn t show a good ability to identify cardiovascular risk factors and components of metabolic syndrome.
Descrição
Palavras-chave
Adolescente, Índice de massa corporal, Riscos cardiovasculares, Síndrome metabólica, Adolescents, Body mass index, Cardiovascular risk, Metabolic syndrome
Citação
QUINTÃO, Denise Félix. Evaluation of different references of body mass index for adolescents in terms of cardiovascular risk and metabolic syndrome in Viçosa, MG. 2010. 129 f. Dissertação (Mestrado em Valor nutricional de alimentos e de dietas; Nutrição nas enfermidades agudas e crônicas não transmis) - Universidade Federal de Viçosa, Viçosa, 2010.