Manuel Bueno

Waist circumference for the screening of the metabolic syndrome in children

Aim: To identify the best anthropometric predictor of the metabolic syndrome in children. Methods: Screening performance was evaluated in a clinical setting. The study included 140 children: 72 non‐obese and 68 with non‐syndromal obesity. Body mass index (BMI), waist circumference and triceps/subscapular skinfolds ratio were used as predictor variables, and systolic blood pressure, diastolic blood pressure, glucose, uric acid, fasting insulin, triglycerides and HDL‐C as metabolic syndrome variables. Results: The areas under the receiver operating characteristic (ROC) curves were 0.849 (95% CI: 0.780,0.919) for BMI, 0.868 (95% CI: 0.801,0.934) for waist circumference and 0.834 (95% CI: 0.757,0.910) for the triceps/subscapular skinfolds ratio. No statistically significant differences were found for the three areas under the ROC curves. The point on the ROC curve closest to 1 corresponded to the 65th percentile for BMI, to the 70th percentile for waist, and to the 40th percentile for the triceps/subscapular skinfolds ratio.

Overweight, obesity and body fat composition in spanish adolescents. The AVENA Study.

Objective: To describe the prevalence of overweight and obesity in the Spanish adolescent population and its relationship with the socioeconomic status, and to assess their body fat composition and compare these results with previous data from our own country. Design: Cross-sectional multicenter study conducted in five Spanish cities (Granada, Madrid, Murcia, Santander and Zaragoza) in 2000–2002. Subjects: 2,320 adolescents with complete set of anthropometric measurements, 1,192 boys and 1,128 girls. Measurements: Body mass index calculated from weight and height measurements, and body fat percentage calculated from skinfold thickness measurements. Results: Overweight + obesity prevalences were 25.69 and 19.13% in boys and girls, respectively. Overweight + obesity prevalence increased in boys from high to medium-low socioeconomic status categories (p = 0.015); meanwhile, there was not a significant effect of socioeconomic status in girls. In males, overweight + obesity prevalence changed from 1985 to 2000–2002 from 13 to 35% and in females from 16 to 32%. The rate of change in overweight + obesity prevalences seems to increase in the last years; from 0.88 (1985 to 1995) to 2.33%/year (1995 to 2000–2002) in males and from 0.5 (1985 to 1995) to 1.83%/year (1995 to 2000–2002) in females. The rate of body fat percentage increase was similar between 1980 and 1995 and between 1995 and 2000–2002: 0.26 and 0.23%/year, respectively, at 13 years of age, and 0.16 and 0.17%/year, respectively, at 14 years of age. Conclusion: We observed elevated overweight and obesity prevalences in Spanish adolescents, similar to those observed in other European countries. There is a significant inverse relationship between socioeconomic status and overweight + obesity, but only in boys. The rate of change in overweight prevalence in Spanish adolescents seems to increase, and the rate of increase of body fat percentage seems to be similar as in previous years.

Harmonization of Anthropometric Measurements for a Multicenter Nutrition Survey in Spanish Adolescents

OBJECTIVE Although the need for accurate anthropometric measurement has been repeatedly stressed, reports on growth and physical measurements in human populations rarely include estimates of measurement error. We describe the standardization process and reliability of anthropometric measurements carried out in a pilot study. METHODS For the intraobserver assessment of anthropometric measurements, we studied 101 adolescents (58 boys and 43 girls) from five cities. For interobserver assessment, we studied 10 adolescents from the same class in Zaragoza and different from those in the intraobserver sample. RESULTS For skinfold thickness, intraobserver technical errors of measurement (TEMs) in general were smaller than 1 mm; for circumferences, TEMs in general were smaller than 1 cm. Intraobserver reliability for skinfold thickness was greater than 95% for almost all cases; for circumferences, intraobserver reliability generally was greater than 95%. Interobserver TEMs ranged from 1 to 2 mm for the six skinfold thicknesses measured; for circumferences, TEMs were smaller than 1 cm for the arm, biceps, and waist and between 1 and 2 cm for the hip and thigh. Interobserver reliabilities for skinfold thickness and circumference were always greater than 90%, except for biceps skinfold. CONCLUSIONS Our results are in agreement with those recommended in the literature. Therefore, these anthropometric measures seem to be adequate to assess body composition in a multicenter survey in adolescents.

Trends in body mass index and overweight prevalence among children and adolescents in the region of Aragón (Spain) from 1985 to 1995.

OBJECTIVE: To analyse trends in body mass index (BMI) and overweight prevalence for children and adolescents in the region of Aragón (Spain), from 1985 to 1995.DESIGN: Nine cross-sectional examinations of schoolchildren conducted yearly from 1985 to 1995.SUBJECTS: A total of 90,997 children (45,970 males and 45,027 females) in the first school year (6–7 y of age); 106,284 scholars (52,772 males and 53,512 females) in the last school year (13–14 y of age).MEASUREMENTS: Heights and weights were measured and BMI (kg/m2) was calculated.RESULTS: We observed a trend to higher BMI values across the surveys, by sex and age. The secular trends in BMI showed the largest increases at the upper ends of the distribution, especially in males. In children in the first school year, prevalences of overweight were higher in females than in males (P<0.001); however, in adolescents in the last school year, prevalences were higher in males than in females (P<0.001). We observed a significant trend in overweight prevalence from 1985 to 1995 in children from the first school year (P=0.0183, in males and P=0.0168, in females). In children in the last school year there was only a significant trend in males (P<0.0001).CONCLUSION: Significant changes in BMI occurred in the population studied during the period 1985–1995, but these changes differ by age and sex. The increasing skewness of BMI in the upper percentiles of the population, especially in boys, suggests that, not only is the pediatric population getting fatter, but the fatter members are becoming more obese. Our results also show a striking increase in the prevalence of overweight children in the region of Aragón (Spain) during the 1985–1995 decade.

Body fat measurement in adolescents: comparison of skinfold thickness equations with dual-energy X-ray absorptiometry.

Objective:To compare the most commonly used equations to predict body fatness from skinfold thickness, in male and female adolescents, with dual-energy X-ray absorptiometry (DXA) as a reference method of fatness measurement.Design:Cross-sectional nutrition survey.Setting:General adolescent population from Zaragoza (Spain).Subjects and methods:A total of 238 Caucasian adolescents (167 females and 113 males), aged 13.0–17.9 y, were recruited from 15 school groups in 11 public and private schools. The percentage fat mass (%FM) was calculated by using skinfold-thickness equations. Predicted %FM was compared with the reference %FM values, measured by DXA. The lack of agreement between methods was assessed by calculating the bias and its 95% limits of agreement.Results:Most equations did not demonstrate good agreement compared with DXA. However, in male adolescents, Slaughter et al equations showed relative biases that were not dependent on body fatness and the limits of agreement were narrower than those obtained from the rest of equations. In females, Brooks equation showed nonsignificant differences against DXA and the narrowest 95% limits of agreement. Only biases from Brook and Slaughter et al equations were not dependent on body fatness in female adolescents.Conclusions:Accuracy of most of the skinfold-thickness equations for assessment of %FM in adolescents was poor at the individual level. Nevertheless, to predict %FM when a relative index of fatness is required in field or clinical studies, Slaughter et al equations may be used in adolescents from both sexes and the Brook equation in female adolescents.Sponsorship:Instituto de Salud Carlos III, Spain.

Homeostatic model assessment (HOMA) index cut-off values to identify the metabolic syndrome in children

The aim of the study was to establish the best cut-off value for the homeostatic model assessment (HOMA) index in identifying children and adolescents with the metabolic syndrome. The study included 72 non-obese and 68 obese children aged 7 to 16 years. Obesity is defined using the criteria proposed by Coleet al., being included as metabolic syndrome variables waist circumference, systolic blood pressure, diastolic blood pressure and seric values of glucose, uric acid, fasting insulin, leptin, triglycerides and HDL-cholesterol. Children were considered as having the metabolic syndrome when four or more characteristics showed abnormal values. The HOMA index was calculated as the product of the fasting plasma insulin level (μU/mL) and the fasting plasma glucose level (mmol/L), divided by 22.5. HOMA index cut-offs from the 5th to the 95th percentile were used. A receiver operating characteristic (ROC) curve was generated using the different HOMA cut-offs for the screening of the metabolic syndrome. The areas under the ROC curve, 95% confidence intervals, and the point to the ROC curve closest to 1, were calculated. The area under the ROC curve was 0.863 (95% C.I.: 0.797, 0.930). The point closest to 1 corresponds to the 60th percentile of the HOMA index distribution in our sample. HOMA index value at the 60th percentile was 2.28. Cut-off values corresponding to a range of HOMA index from the 50 to the 75 percentile, showed similar distances to 1. HOMA index values for percentiles 50 to 75 ranged from 2.07 to 2.83. In conclusion, HOMA index could be a useful tool to detect children and adolescents with the metabolic syndrome. HOMA cut-off values need to be defined in the paediatric population; however, values near to 3 seem to be adequate.ResumenEl objetivo del estudio era establecer el mejor punto de corte del índice HOMA (Homeostatic Model Assessment) para la identificación de niños y adolescentes con el síndrome metabólico. Se incluyeron 72 niños noobesos y 68 obesos, con edades entre 7 y 16 años. Se definió obesidad según los criterios propuestos por Cole y cols. Las variables utilizadas para describir el síndrome metabólico fueron las siguientes: Perímetro de la cintura, tensión arterial sistólica y diastólica, glucosa, ácido úrico, insulina en ayunas, leptina, triglicéridos y HDL-colesterol. Se consideraba que un niño tenía el síndrome metabólico cuando presentaba cuatro o más de estas características con valores anormales. El índice HOMA se calculó como el producto de las concentraciones de insulina en ayunas (μU/mL) y la glucosa plasmática en ayunas (mmol/L), dividido por 22.5. Se calcularon puntos de corte del índice HOMA correspondientes a los percentiles entre 5 y 95. Se elaboró una curva ROC (Receiver Operating Characteristics) tomando los diferentes puntos de corte del índice HOMA para la identificación del síndrome metabólico. Se calculó el área bajo la curva ROC, los intervalos de confianza al 95% y el punto de la curva ROC más cercano a 1. El área bajo la curva fue 0.863 (IC 95%: 0.797, 0.930). El punto más cercano a 1 correspondía al percentil 60 del índice HOMA en nuestra muestra. El valor del índice HOMA para el percentil 60 era 2.28. Puntos de corte del índice HOMA correspondientes a los percentiles comprendidos entre 50 y 75, mostraban distancias similares a 1. Los valores de índice HOMA correspondientes a estos percentiles oscilaban entre 2.07 y 2.83. En conclusión, el índice HOMA puede ser un buen instrumento para detectar el síndrome metabólico en niños y adolescentes. Es necesario definir mejor el punto de corte a utilizar en la población pediátrica; sin embargo, valores cercanos a 3 parecen ser los más adecuados.

Cardiorespiratory Fitness and Sedentary Activities Are Associated with Adiposity in Adolescents

Objective: To determine whether physical activity, sedentary activities, and/or cardiorespiratory fitness are related to waist circumference in adolescents, as previously reported in adults.

Waist circumference values in Spanish children—Gender related differences

Objective: To obtain reference values of the waist circumference in Spanish children, and to investigate their dependence on age and gender.Design: Cross-sectional study.Setting: General school-age population.Subjects: A representative sample of the schools in Zaragoza, Spain, was drawn from seven schools. The population selected comprised 1728 children with ages ranging from 6.0–14.9 y. Of the original sample, 368 children (21.29%) were excluded because of chronic diseases or refusal. Finally, 1360 children and adolescents: 701 boys and 659 girls, were studied.Interventions: Waist and hip circumferences were measured with an unelastic tape.Results: Waist circumference tended to be higher in males than in females and this difference was significant after 11.5 y. In general, hip circumference was higher in females than in males (statistically significant differences at 7.5, 10.5, 12.5 and 13.5 y). In general, percentile values of waist circumference were higher in males than in females, especially after 12.5 y. Difference between males and females on percentile 95 at 14.5 y was 7.6 cm. Hip was greater than waist in both sexes, and the two curves run nearly parallel in males. In females, while hip enlarges continuously, waist shows the reverse tendency between 11.5 and 14.5 y.Conclusions: Waist circumference showed higher values in boys than in girls, especially after 11.5 y, and waist values increase with age both in males and females. These findings justify the use of age and gender specific reference standards.Sponsorship: This work was supported by grant 216-02 from Universidad de Zaragoza, Zaragoza, Spain.

Body composition in adolescents: measurements and metabolic aspects

INTRODUCTION: Adolescence is a decisive period in human life in which important body composition changes occur. Increase of total body mass and its relative distribution are mainly related to gender and pubertal development.OBJECTIVE: This review explores the specific measurements that may be used in this age group to assess excess body fat and to define obesity and overweight.RESULTS: Identification of subjects at risk for adiposity requires simple anthropometric cutoffs for the screening of overweight and obesity. In this context, BMI criterion is the most frequently used but, in spite of its high sensitivity and specificity, an important number of adolescents classified as overweight or obese do not have really high adiposity (32.1% of females and 42% of males). Excess total body fat and intra-abdominal visceral fat are related to metabolic abnormalities that increase the risk of cardiovascular diseases. Waist circumference seems to be the best simple anthropometric predictor for the screening of the metabolic syndrome in children and adolescents.CONCLUSIONS: Early identification of adolescents at risk for adiposity and its related metabolic complications requires reliable, simple and specific measures of excess body fat for this age group.

Skinfold thickness measurements are better predictors of body fat percentage than body mass index in male Spanish children and adolescents

Objective: To develop equations, from some simple anthropometric measurements, for the prediction of body density from underwater weighing in male spanish children and adolescents.Subjects: One hundred and seventy-five males, aged 7.0–16.9 y, participated in this study, they were recruited from primary and secondary schools.Measurements: Body weight and height and skinfold thicknesses by anthropometry, body density by underwater weighing.Results: Correlations between body density and body mass index (BMI) were high until 14.0–16.9 y. Correlations between body density and log Σ 4 skinfolds were higher than those with BMI at all ages. Log Σ 4 skinfolds explained between 61% (14.0–16.9 y) and 68% (11.0–13.9 y) of the body density variance. Regression equations for body density from BMI and triceps skinfold thickness explained between 51% (14.0–16.9 y) and 68% (7.0–10.9 y) of the body density variance.Conclusions: The best estimators of body density in the children and adolescents studied were log Σ 4 skinfolds and a combination of BMI and triceps skinfold.Sponsorship: Universidad de Zaragoza