Indicadores antropométricos, de composição corporal e bioquímicos para predição do índice HOMA-IR em homens adultos
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2008-06-09
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Universidade Federal de Viçosa
Resumo
O presente estudo objetivou avaliar a eficácia de indicadores antropométricos e de composição corporal e de indicadores bioquímicos do perfil lipídico plasmático em predizer o índice HOMA-IR em homens. Realizou-se um estudo de delineamento transversal, no qual foram avaliados 138 indivíduos adultos (20 59 anos) saudáveis. A avaliação antropométrica constou da determinação do peso, da estatura, do diâmetro abdominal sagital (DAS) e dos perímetros da cintura (PC), do quadril e da coxa. O PC e o DAS foram aferidos em quatro locais anatômicos distintos. A composição corporal foi avaliada por bioimpedância elétrica. Os nove indicadores antropométricos e de composição corporal estudados foram analisados segundo o tipo de obesidade que se propõe a avaliar: indicadores de obesidade central (PC, DAS, índice de conicidade e relação cintura/estatura), indicadores de obesidade geral (índice de massa corporal e percentual de gordura corporal) e indicadores de distribuição de gordura corporal (relação cintura/quadril, relação cintura/coxa e índice sagital). Os indicadores bioquímicos do perfil lipídico analisados foram o colesterol total (CT), o HDL-C, o LDL-C e os triglicérides (TG). As relações CT/HDL-C e TG/HDL-C foram calculadas. O índice HOMA-IR (Homeostasis Model Assessment Insulin Resistance), indicador de resistência à insulina (RI), foi calculado pela fórmula: HOMA-IR = insulinemia de jejum (µU/mL) x glicemia de jejum (mmol/L) / 22,5, sendo considerado para as análises o ponto de corte referente ao percentil 75. A análise estatística constou da análise de correlação intraclasse, da análise de variância com o teste post-hoc de Tukey, do teste de Kruskall-Wallis com o teste post-hoc de Dunn s, dos coeficientes de correlação de Spearman e Pearson e da construção de curvas ROC (Receiver Operating Characteristic Curve). Verificou-se elevada reprodutibilidade para todas as medidas do PC e do DAS, com coeficientes de correlação intraclasse variando de 0,986 a 0,999 (p<0,001). O PC aferido na menor cintura e o DAS aferido no maior diâmetro abdominal diferiram dos demais locais. Entre os locais testados, a menor cintura entre o tórax e o quadril, para o DAS, e o ponto médio entre a crista ilíaca e a última costela, para o PC, foram os locais que apresentaram as correlações mais fortes com o HOMA-IR (r = 0,482 e 0,464; p<0,001) e as maiores áreas abaixo das curvas ROC (0,716 ± 0,051 e 0,746 ± 0,049; p<0,001) respectivamente, e, conseqüentemente, apresentaram melhor eficiência em predizer o risco de RI. Entre os nove indicadores de obesidade analisados, o PC e o DAS foram os mais promissores para avaliação do risco de RI. Os valores de 89,3 cm (sensibilidade = 80% e especificidade = 66%) para o PC e de 20,0 cm (sensibilidade = 77,1% e especificidade = 68%) para o DAS foram os pontos de corte que apresentaram maior acurácia para a predição de níveis mais elevados do HOMA-IR. Para os indicadores bioquímicos do perfil lipídico, constatou-se que a RTG/HDL-C foi a que apresentou correlação mais forte (r =0,334; p<0,001) e maior área abaixo da curva ROC (0,724 ± 0,046; p<0,001), resultando em melhor eficácia para a predição do índice HOMA-IR. Sugere-se a utilização desses três indicadores como instrumentos alternativos para a predição de RI na prática clínica. Contudo, ressalta-se a necessidade de maior número de investigações acerca do comportamento desses indicadores na predição de RI em amostras maiores, abrangendo outros extratos da população brasileira, incluindo mulheres, adolescentes e idosos, o que viabilizará a utilização desses indicadores de RI nos screenings populacionais e na prática clínica, de forma padronizada, respeitando as características da nossa população.
This study aimed to evaluate the effectiveness of anthropometric and body composition indicators and lipid profile biochemical indicators in predicting the HOMA-IR index in men. The study was conducted in a cross-sectional design, in which 138 healthy adults (20 - 59 years) were evaluated. The anthropometric evaluation consisted of determining weight, height, sagittal abdominal diameter (SAD) and waist (WP), hip and thigh perimeters. The WP and SAD were measured in four distinct anatomical sites. The body composition was assessed by bioelectrical impedance. The nine anthropometric and body composition indicators studied were analyzed by the type of obesity that is intended to assess: central obesity indicators (WP, SAD, conicity index and waist/height ratio), general obesity indicators (body mass index and body fat percentage) and body fat distribution indicators (waist/hip ratio, waist/thigh ratio and sagittal index). The lipid profile biochemical indicators examined were: total cholesterol (TC), HDL-C, LDL-C and triglycerides (TG). The ratios TC/HDL-C and TG/HDL-C were calculated. The HOMA-IR index (Homeostasis Model Assessment - Insulin Resistance), an indicator of insulin resistance (IR), was calculated by the formula: HOMA-IR = fasting insulin (μU/mL) x fasting plasma glucose (mmol/L)/22.5, considering for the analyses the percentile 75 as the cut-off point. Statistical analysis consisted of intraclass correlation, analysis of variance with Tukey post-hoc test, Kruskall-Wallis test with Dunn's post-hoc test, the Spearman and Pearson correlation coefficients and ROC (Receiver Operating Characteristic) curves. There was high reproducibility for all WP and SAD measures, with an intraclass correlation coefficient ranging from 0.986 to 0.999 (p < 0.001). The WP measured in the lower waist and the SAD measured in the largest diameter differed from other locations. Among the anatomical sites tested, the lower waist between the chest and hip, for the SAD, and the midpoint between the iliac crest and the last rib, for the WP, were the sites that showed the strongest correlations with HOMA-IR (r = 0.482 and 0.464, p < 0.001) and the largest areas under the ROC curves (0.716 ± 0.051 and 0.746 ± 0.049, p < 0.001) respectively, and therefore, showed better performance in predicting IR risk. Among the nine indicators of obesity tested, the WP and SAD were the most promising for assessing the IR risk. The values of 89.3 cm (sensitivity = 80% and specificity = 66%) for the WP and 20.0 cm (sensitivity = 77.1% and specificity = 68%) for the SAD were the cut-off points that showed the most accurate prediction for HOMA-IR higher levels. For the lipid profile biochemical indicators, it was found that the TG/HDL-C ratio presented the strongest correlation (r = 0.334, p < 0.001) with HOMA-IR and largest area under the ROC curve (0.724 ± 0.046, p < 0.001), resulting in better performance for the prediction of the HOMA-IR index. The use of these three indicators as instruments for the IR prediction in clinical practice is advisable. However, the necessity of a greater number of investigations about the performance of these indicators in the IR prediction in larger samples should be pointed out, reaching other extracts of the Brazilian population, including women, adolescents and elderly, which would allow the use of these IR indicators in population screenings and in clinical practice, in a standardized way, respecting our population s characteristics.
This study aimed to evaluate the effectiveness of anthropometric and body composition indicators and lipid profile biochemical indicators in predicting the HOMA-IR index in men. The study was conducted in a cross-sectional design, in which 138 healthy adults (20 - 59 years) were evaluated. The anthropometric evaluation consisted of determining weight, height, sagittal abdominal diameter (SAD) and waist (WP), hip and thigh perimeters. The WP and SAD were measured in four distinct anatomical sites. The body composition was assessed by bioelectrical impedance. The nine anthropometric and body composition indicators studied were analyzed by the type of obesity that is intended to assess: central obesity indicators (WP, SAD, conicity index and waist/height ratio), general obesity indicators (body mass index and body fat percentage) and body fat distribution indicators (waist/hip ratio, waist/thigh ratio and sagittal index). The lipid profile biochemical indicators examined were: total cholesterol (TC), HDL-C, LDL-C and triglycerides (TG). The ratios TC/HDL-C and TG/HDL-C were calculated. The HOMA-IR index (Homeostasis Model Assessment - Insulin Resistance), an indicator of insulin resistance (IR), was calculated by the formula: HOMA-IR = fasting insulin (μU/mL) x fasting plasma glucose (mmol/L)/22.5, considering for the analyses the percentile 75 as the cut-off point. Statistical analysis consisted of intraclass correlation, analysis of variance with Tukey post-hoc test, Kruskall-Wallis test with Dunn's post-hoc test, the Spearman and Pearson correlation coefficients and ROC (Receiver Operating Characteristic) curves. There was high reproducibility for all WP and SAD measures, with an intraclass correlation coefficient ranging from 0.986 to 0.999 (p < 0.001). The WP measured in the lower waist and the SAD measured in the largest diameter differed from other locations. Among the anatomical sites tested, the lower waist between the chest and hip, for the SAD, and the midpoint between the iliac crest and the last rib, for the WP, were the sites that showed the strongest correlations with HOMA-IR (r = 0.482 and 0.464, p < 0.001) and the largest areas under the ROC curves (0.716 ± 0.051 and 0.746 ± 0.049, p < 0.001) respectively, and therefore, showed better performance in predicting IR risk. Among the nine indicators of obesity tested, the WP and SAD were the most promising for assessing the IR risk. The values of 89.3 cm (sensitivity = 80% and specificity = 66%) for the WP and 20.0 cm (sensitivity = 77.1% and specificity = 68%) for the SAD were the cut-off points that showed the most accurate prediction for HOMA-IR higher levels. For the lipid profile biochemical indicators, it was found that the TG/HDL-C ratio presented the strongest correlation (r = 0.334, p < 0.001) with HOMA-IR and largest area under the ROC curve (0.724 ± 0.046, p < 0.001), resulting in better performance for the prediction of the HOMA-IR index. The use of these three indicators as instruments for the IR prediction in clinical practice is advisable. However, the necessity of a greater number of investigations about the performance of these indicators in the IR prediction in larger samples should be pointed out, reaching other extracts of the Brazilian population, including women, adolescents and elderly, which would allow the use of these IR indicators in population screenings and in clinical practice, in a standardized way, respecting our population s characteristics.
Descrição
Palavras-chave
Resistência à insulina, Antropometria, Obesidade, Lipoproteínas, Insulin resistance, Antropometry, Obesity, Lipoproteins
Citação
VASQUES, Ana Carolina Junqueira. Anthropometric, body composition and biochemical indicators for the prediction of the HOMA-IR index in adult men. 2008. 5 f. Dissertação (Mestrado em Valor nutricional de alimentos e de dietas; Nutrição nas enfermidades agudas e crônicas não transmis) - Universidade Federal de Viçosa, Viçosa, 2008.