[Overweight and Obesity in Children and Adolescents: Comparison of Three Classification Criteria Based on Body Mass Index]

Objective: To describe and compare the nutritional status of children and adolescents using three body mass index (BMI)-based criteria; to analyze the agreement between these criteria in terms of frequency of excess weight; and to investigate if the factors associated with excess weight were similar for the three criteria.

Methods: The following criteria were investigated: 2000 International Obesity Task Force (IOTF), 2006 Conde and Monteiro, and 2007 World Health Organization (WHO). Weight, height, and physical fitness were measured in 525 students from urban and rural schools, with ages between 7 and 15 years (mean = 11.0 ± 2.1). The McNemar test, kappa statistics, and Poisson regression were used to evaluate each objective, respectively.

Results: The overall prevalence of excess weight (overweight + obesity) was 28.4% with the IOTF, 35.1% with the WHO, and 35.8% with Conde and Monteiro. There were no differences between criteria concerning overall prevalence of excess weight in males and females. However, within each sex, different results were observed for specific age groups, especially between 7 and 9 years. Nevertheless, the agreement (kappa) between the criteria was satisfactory: 0.71 to 0.98, depending on sex and age. The factors associated with excess weight and the strength of associations were similar for the three criteria.

Conclusions: The prevalence of excess weight obtained with the IOTF was 20% lower than that calculated with the other criteria. Despite the differences between sexes observed for some age groups, the agreement between the three criteria was relatively high, and the factors associated with excess weight were similar. Further studies employing similar methods are required to confirm the present results in different populations of children and adolescents.