Performance of references based on body mass index for detecting excess body fatness in schoolchildren aged 7 to10 years

Abstract

AbstrAct:Objective: To compare the sensitivity and specificity of body mass index (BMI)-based classification systems and to determine the optimal cut-offs for predicting excess body fatness in schoolchildren. Methods: 2795 schoolchildren aged 7 -10 years were examined. Excess body fatness was defined as the standardized residuals of the sum of three skinfold thickness ranking at or above the 90th percentile. The international BMI-based system recommended by the World Health Organization (WHO-2007) was evaluated on the basis of its sensitivity and specificity for detecting excess body fatness and compared with a national BMI reference (Brazil-2006). Likelihood ratios analysis was used to select the optimal cut-offs in each curve. Results: The two classification systems presented high sensitivity (92.5 -98.6%) and moderate specificity (75.9 -85.0%) for both sexes. The optimal BMI cut-offs improved specificity with no marked loss of sensitivity. Using the proposed BMI cut-offs, the post-test probability of predicting excess body fatness for children classified as non-overweight decreased from 10 (pre-test probability) to 1.4% in girls and to 1.1% in boys. For overweight children, this probability increased to more than 46.0%. Conclusion:The results showed that both the WHO-2007 and Brazil-2006 classification systems can be used as screening instruments for excess body fatness, and that one of the limitations of using the BMI-for-age references could be improved by refining the existing cut-offs.

New Reference Parameters for Body Mass Index in Children Aged Six to Ten Years

“…These differences are present in several studies that aimed to compare the performances and specificities of reference values established by the Center for Disease Control and Prevention (CDC), 24 IOTF, 15 Conde and Monteiro, 17 World Health Organization (WHO), 25 among others. 19 , 26 …”

Body mass index and association with use of and distance from places for physical activity and active leisure among schoolchildren in Brazil. Cross-sectional study

“…29 BMI, as evaluated according to the WHO criteria, 30 has shown high sensitivity (92.5%) for detecting excess body fatness in schoolchildren aged 7-10 years living in Florianópolis. 31 Hence, we defined overweight as BMI for age and sex ≥ +1 and < +2 z-scores and obesity as BMI for age and sex ≥ + 2 z-scores. 30 In addition, we evaluated waist circumference (WC) in our sample.…”