Validation of capillary glycemia as a strategy for the screening of diabetes mellitus in adolescents.

OBJECTIVE: To compare the degree of concordance between plasma and capillary glucose for screening of diabetes mellitus in adolescents. METHODS: The plasma and capillary glucose of 119 adolescents aged 10-19 yr (36 males and 83 females) from public schools in Niterói, Rio de Janeiro State, Brazil, were verified after a 12-h fast. Agreement was assessed through kappa statistics (k), McNemar's chi-squared test, and the intraclass correlation coefficient (ICC). The paired Student's t-test for comparison of means, the approaches by Altman and Bland, and the survival-agreement plot were also applied. RESULTS: Mean values of plasma glucose were 7.9 points higher than the capillary values (91.5 vs. 83.6 mg/dL, p < 0.001; ICC = 0.419). A regular agreement between the methods (k = 0.31, p < 0.001) for assessing proportions of adolescents with glycemia > or =100 mg/dL is observed. Using the strategy of adding 8 mg/dL to the capillary levels, the agreement improved (k = 0.46, p < 0.001) and a significant difference was not observed between the estimated prevalences (p = 0.815). CONCLUSIONS: The results suggest a satisfactory agreement between the two methods when capillary glucose is corrected, and this may be a useful and low-cost tool for the epidemiologic investigation of diabetes mellitus prevalence in adolescents.

Desempenho de pontos de corte do índice de massa corporal de diferentes referências na predição de gordura corporal em adolescentes / Accuracy of different body mass index reference values to predict body fat in adolescents

Avaliamos a acurácia de pontos de corte do índice de Massa Corporal (IMC) para identificar adolescentes com sobrepeso, comparando com percentual de gordura corporal, estimado pela bioimpedância elétrica, em uma amostra probabilística de 610 adolescentes de 12 a 19 anos (222 meninos e 388 meninas), estudantes de escolas públicas de Niterói, Rio de Janeiro, Brasil. A curva ROC foi utilizada para avaliar a sensibilidade e especificidade de pontos de corte de IMC de uma referência nacional, duas norte-americanas e uma internacional. Os pontos de corte da amostra estudada foram inferiores aos das demais referências, com sensibilidade de 76 por cento a 95 por cento e especificidade de 75 por cento a 95 por cento. Os pontos de corte nacionais foram também mais sensíveis (53 por cento a 100 por cento), se comparados às outras referências (40 por cento a 86 por cento). O critério internacional apresentou melhor sensibilidade para adolescentes mais velhos e as referências americanas, para os mais jovens. O IMC foi um bom proxy de adiposidade, mas o uso de pontos de corte de referências de outras populações merece cautela, pois pode gerar erro na classificação de adolescente com sobrepeso em até 60 por cento.

[Accuracy of different body mass index reference values to predict body fat in adolescents]. / Desempenho de pontos de corte do índice de massa corporal de diferentes referências na predição de gordura corporal em adolescentes.

This study evaluates the accuracy of cutoff points in the body mass index (BMI) for identifying adolescents with overweight, compared to the percentage of body fat, estimated by electric bioimpediance, in a probabilistic sample of 610 adolescents from 12 to 19 years of age (222 boys and 388 girls) enrolled in public schools in Niterói, Rio de Janeiro, Brazil. ROC was used to evaluate the sensitivity and specificity of BMI cutoffs from one Brazilian, two North American, and one international reference. The cutoff points in the study sample were lower than the other references, with 76% to 95% sensitivity and 75% to 95% specificity. The Brazilian cutoff points were also more sensitive (53% to 100%) as compared to the other references (40% to 86%). The international parameter showed better sensitivity for older adolescents, and the Northern American references for younger adolescents. BMI was a good proxy for adiposity, but cutoff points from other population references should be used with caution, since they can lead to classification errors in adolescents with overweight.

Insulin resistance in Brazilian adolescent girls: association with overweight and metabolic disorders.

We assessed the association between insulin resistance, overweight and metabolic disorders in a probabilistic sample of 388, 12-19-year-old girls from public schools in Niterói, Rio de Janeiro State, Brazil. Insulin resistance was determined using Homeostatic Model Assessment-Insulin Resistance (HOMA-IR). Overweight and obesity were defined by the sex- and age-specific body mass index cut-offs recommended by the International Obesity Task Force. Metabolic syndrome (MS) was identified by the presence of at least three of the following factors: fasting glucose >or=100mg/dL, triglycerides >130 mg/dL, LDL-C >or=110 mg/dL, HDL-C <35 mg/dL and overweight. The combined prevalence of obesity (2.9%) and overweight was 14.2%. The average HOMA-IR level was 2.24 (95% confidence interval=1.40-3.10) in the overweight group and 1.91 (95% CI=1.32-2.50) in the non-overweight one, and MS prevalence was 20 times higher in the first group (21.4 and 0.1%). MS prevalence in the overweight group was 6.3 times higher in adolescents above the 66th percentile of HOMA-IR (55.9%) than those under the 33rd percentile (8.9%). Brazilian overweight girls with higher insulin resistance had high risk of developing MS. Therefore, prevention should occur at an early age to impair the evolution of this process.

Ìndice de massa corporal na avaliação de sobrepeso e obesidade em crianças e adolescentes: concordâncias e controvérsias / Body mass index in assessment of overweight and obesity in children and adolescents: agreement and disagreement

A obesidade na infância e adolescência vem aumentando rapidamente no Brasil e no mundo sem necessários métodos de investigação práticos e viáveis que estimem sua prevalência e permitam comparações internacionais. O índice de massa corporal (IMC - massa corporal/estatura) foi proposto pela OMS como o melhor índice para esta avaliação, considerando a sua alta correlação em medidas de adiposidade e de massa corporal, a facilidade de ser obtido e ainda o fato de permitir uma continuidade do critério usado para adultos. Todavia, algumas limitações como a correlação com a estatura que, apesar de baixa significativa, e o fato de não refletir adequadamente as mudanças na composião corporal que ocorrem na adolescência, sugerem cautela na interpretaão desse índice como medida de adiposidade em fase de crescimento...