Marlene Merino Alvarez

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 Niteroi, 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.

Associação das medidas antropométricas de localização de gordura central com os componentes da síndrome metabólica em uma amostra probabilística de adolescentes de escolas públicas

It was investigated the association of waist circumference (WC), abdominal circumference (AC), Waist-to-Hip ratio(WHR) and Waist-Height ratio (WHtR) adjusted by body mass index (BMI) and % body fat (BF) with metabolic syndrome components in a probabilistic sample of 610 adolescents aged 12-19 years (222 boys and 388 girls) from public schools of Niterói, Rio de Janeiro. Fasting glucose and lipids were assayed using automated enzymatic method and insulin was determined by radioimmuno assay. Systolic (SBP) and diastolic (DBP) blood pressure were measured using an automated recorder and % BF by electric bioimpedance. The association of the anthropometric measures with metabolic syndrome components was evaluated by multivariate linear regression adjusted according to the age, BMI or %BF. In boys, a positive association between WC (beta=1.03 p<0.01) and WHtR (beta= 2.33, p< 0.05; beta=2.12 and p< 0.01) with triglycerides was maintained after BMI and % BF adjusting, respectively. WC was associated with SBP after % BF adjusting both for boys (beta= 0.70 p<0.01) and girls (beta=0.68 p<0.01). In conclusion, WC was the measure of central body fat that presented the best association with components of metabolic syndrome in adolescents.

Body mass index for predicting hyperglycemia and serum lipid changes in Brazilian adolescents

OBJETIVO: Determinar os melhores pontos de corte do indice de massa corporal (IMC) para identificar alteracoes no perfil lipemico e glicemico em adolescentes. METODOS: Foram avaliados 577 adolescentes de 12 a 19 anos (210 meninos e 367 meninas) em uma amostra probabilistica de estudantes de escolas estaduais da cidade de Niteroi (RJ), em 2003. Foi utilizada a curva Receiver Operating Characteristic para identificar o melhor ponto de corte, ajustado para idade, para predizer valores elevados de colesterol total serico (>150mg/dL), LDL-C (>100mg/dL), triglicerides (>100mg/dL), glicose plasmatica (>100mg/dL) e baixos valores de HDL-C ( 50%) foram: colesterol total elevado e HDL-C baixa. O IMC foi capaz de predizer valores elevados de triglicerides nos meninos, LDL-C nas meninas e colesterol total e presenca de tres ou mais alteracoes metabolicas em ambos os sexos (area sob a curva - 0,59 a 0,67), embora com baixa sensibilidade (57% a 66%) e especificidade (58% a 66%). Os melhores pontos de corte na amostra estudada (20,3 kg/m² a 21,0 kg/m²) foram inferiores aos propostos pelas outras referencias. CONCLUSOES: Embora valores de IMC menores do que os das referencias internacionais tenham sido preditores de algumas alteracoes metabolicas em adolescentes brasileiros, o IMC nao foi um bom indice para identificar estas anormalidades na amostra estudada.OBJECTIVE To determine the best cut-offs of body mass index for identifying alterations of blood lipids and glucose in adolescents. METHODS A probabilistic sample including 577 adolescent students aged 12-19 years in 2003 (210 males and 367 females) from state public schools in the city of Niterói, Southeastern Brazil, was studied. The Receiver Operating Characteristic curve was used to identify the best age-adjusted BMI cut-off for predicting high levels of serum total cholesterol (> or =150 mg/dL), LDL-C (> or =100 mg/dL), serum triglycerides (> or =100 mg/dL), plasma glucose (> 100 mg/dL) and low levels of HDL-C (< 45 mg/dL). Four references were used to calculate sensitivity and specificity of BMI cut-offs: one Brazilian, one international and two American. RESULTS The most prevalent metabolic alterations (>50%) were: high total cholesterol and low HDL-C. BMI predicted high levels of triglycerides in males, high LDL-C in females, and high total cholesterol and the occurrence of three or more metabolic alterations in both males and females (areas under the curve range: 0.59 to 0.67), with low sensitivity (57%-66%) and low specificity (58%-66%). The best BMI cut-offs for this sample (20.3 kg/m(2) to 21.0 kg/m(2)) were lower than those proposed in the references studied. CONCLUSIONS Although BMI values lower than the International cut-offs were better predictor of some metabolic abnormalities in Brazilian adolescents, overall BMI is not a good predictor of these abnormalities in this population.

Prevalence of metabolic syndrome and of its specific components among adolescents from Niterói City, Rio de Janeiro State, Brazil

OBJECTIVE To compare the prevalence of metabolic abnormalities (MA) and metabolic syndrome (MS) assessed by different criteria among Brazilian adolescents. SUBJECTS AND METHODS Weighted prevalence of MA and MS were estimated using criteria adapted from the International Diabetes Federation (IDF), National Cholesterol Education Program, Adult Treatment Panel III (NCEP/ATP III), and the World Health Organization (WHO) in a probabilistic sample of 577 students aged 12-19. RESULTS The most prevalent MA was low concentration of HDL-C as per IDF (32.5%) and NCEP/ATP III (41.6%) criteria and hypertension as per the WHOs criterion (12.4%). Prevalence of MS using the NCEP/ATP III criterion (6.04%) was five times higher than the WHOs (1.1%) and the IDFs (1.6%) criteria. As expected, MS was significantly higher among overweight than among non-overweight adolescents. CONCLUSION Low prevalence of MS but high prevalence of some MA were found. These findings suggest that the diagnosis of MA is more relevant in clinical practice especially in overweight adolescents.

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.

Índice de massa corporal para predizer hiperglicemia e alterações lipídicas em adolescentes brasileiros

OBJETIVO: Determinar os melhores pontos de corte do indice de massa corporal (IMC) para identificar alteracoes no perfil lipemico e glicemico em adolescentes. METODOS: Foram avaliados 577 adolescentes de 12 a 19 anos (210 meninos e 367 meninas) em uma amostra probabilistica de estudantes de escolas estaduais da cidade de Niteroi (RJ), em 2003. Foi utilizada a curva Receiver Operating Characteristic para identificar o melhor ponto de corte, ajustado para idade, para predizer valores elevados de colesterol total serico (>150mg/dL), LDL-C (>100mg/dL), triglicerides (>100mg/dL), glicose plasmatica (>100mg/dL) e baixos valores de HDL-C ( 50%) foram: colesterol total elevado e HDL-C baixa. O IMC foi capaz de predizer valores elevados de triglicerides nos meninos, LDL-C nas meninas e colesterol total e presenca de tres ou mais alteracoes metabolicas em ambos os sexos (area sob a curva - 0,59 a 0,67), embora com baixa sensibilidade (57% a 66%) e especificidade (58% a 66%). Os melhores pontos de corte na amostra estudada (20,3 kg/m² a 21,0 kg/m²) foram inferiores aos propostos pelas outras referencias. CONCLUSOES: Embora valores de IMC menores do que os das referencias internacionais tenham sido preditores de algumas alteracoes metabolicas em adolescentes brasileiros, o IMC nao foi um bom indice para identificar estas anormalidades na amostra estudada.OBJECTIVE To determine the best cut-offs of body mass index for identifying alterations of blood lipids and glucose in adolescents. METHODS A probabilistic sample including 577 adolescent students aged 12-19 years in 2003 (210 males and 367 females) from state public schools in the city of Niterói, Southeastern Brazil, was studied. The Receiver Operating Characteristic curve was used to identify the best age-adjusted BMI cut-off for predicting high levels of serum total cholesterol (> or =150 mg/dL), LDL-C (> or =100 mg/dL), serum triglycerides (> or =100 mg/dL), plasma glucose (> 100 mg/dL) and low levels of HDL-C (< 45 mg/dL). Four references were used to calculate sensitivity and specificity of BMI cut-offs: one Brazilian, one international and two American. RESULTS The most prevalent metabolic alterations (>50%) were: high total cholesterol and low HDL-C. BMI predicted high levels of triglycerides in males, high LDL-C in females, and high total cholesterol and the occurrence of three or more metabolic alterations in both males and females (areas under the curve range: 0.59 to 0.67), with low sensitivity (57%-66%) and low specificity (58%-66%). The best BMI cut-offs for this sample (20.3 kg/m(2) to 21.0 kg/m(2)) were lower than those proposed in the references studied. CONCLUSIONS Although BMI values lower than the International cut-offs were better predictor of some metabolic abnormalities in Brazilian adolescents, overall BMI is not a good predictor of these abnormalities in this population.

Índice de masa corporal para predecir hiperglicemia y alteraciones lipídicas en adolescentes brasileros

OBJETIVO: Determinar os melhores pontos de corte do indice de massa corporal (IMC) para identificar alteracoes no perfil lipemico e glicemico em adolescentes. METODOS: Foram avaliados 577 adolescentes de 12 a 19 anos (210 meninos e 367 meninas) em uma amostra probabilistica de estudantes de escolas estaduais da cidade de Niteroi (RJ), em 2003. Foi utilizada a curva Receiver Operating Characteristic para identificar o melhor ponto de corte, ajustado para idade, para predizer valores elevados de colesterol total serico (>150mg/dL), LDL-C (>100mg/dL), triglicerides (>100mg/dL), glicose plasmatica (>100mg/dL) e baixos valores de HDL-C ( 50%) foram: colesterol total elevado e HDL-C baixa. O IMC foi capaz de predizer valores elevados de triglicerides nos meninos, LDL-C nas meninas e colesterol total e presenca de tres ou mais alteracoes metabolicas em ambos os sexos (area sob a curva - 0,59 a 0,67), embora com baixa sensibilidade (57% a 66%) e especificidade (58% a 66%). Os melhores pontos de corte na amostra estudada (20,3 kg/m² a 21,0 kg/m²) foram inferiores aos propostos pelas outras referencias. CONCLUSOES: Embora valores de IMC menores do que os das referencias internacionais tenham sido preditores de algumas alteracoes metabolicas em adolescentes brasileiros, o IMC nao foi um bom indice para identificar estas anormalidades na amostra estudada.OBJECTIVE To determine the best cut-offs of body mass index for identifying alterations of blood lipids and glucose in adolescents. METHODS A probabilistic sample including 577 adolescent students aged 12-19 years in 2003 (210 males and 367 females) from state public schools in the city of Niterói, Southeastern Brazil, was studied. The Receiver Operating Characteristic curve was used to identify the best age-adjusted BMI cut-off for predicting high levels of serum total cholesterol (> or =150 mg/dL), LDL-C (> or =100 mg/dL), serum triglycerides (> or =100 mg/dL), plasma glucose (> 100 mg/dL) and low levels of HDL-C (< 45 mg/dL). Four references were used to calculate sensitivity and specificity of BMI cut-offs: one Brazilian, one international and two American. RESULTS The most prevalent metabolic alterations (>50%) were: high total cholesterol and low HDL-C. BMI predicted high levels of triglycerides in males, high LDL-C in females, and high total cholesterol and the occurrence of three or more metabolic alterations in both males and females (areas under the curve range: 0.59 to 0.67), with low sensitivity (57%-66%) and low specificity (58%-66%). The best BMI cut-offs for this sample (20.3 kg/m(2) to 21.0 kg/m(2)) were lower than those proposed in the references studied. CONCLUSIONS Although BMI values lower than the International cut-offs were better predictor of some metabolic abnormalities in Brazilian adolescents, overall BMI is not a good predictor of these abnormalities in this population.