Analysis of the relationship between two methods indicating nutritional status in schoolchildren

Abstract

Objective. Verify the agreement of diagnoses from the use of two methods of nutritional status indicators -body mass index (BMI) and body fat percentage (% BF)- in students of 6-12 years old from three cities of the state of Rio Grande do Sul, Brazil.

Method. The study group consisted of 507 school children, 261 boys and 246 girls. Anthropometric variables were collected for the calculation of BMI and % BF, using the criteria for classification reference Conde and Monteiro (2006) and Lohman (1987), respectively.

Results. The results were analyzed by Pearson correlation and Kappa index. The data showed a positive correlation of 0,89 to boys and 0,78 to girls among variables. The agreement between the methods analyzed using the Kappa index showed that 54,9% of girls and 56,7% of boys were in the same category classified by both procedures.

Conclusion. It can be concluded that although they show a high correlation between BMI and % BF methods, they differ widely in classifying individuals aged 6-12 years, and this is even more pronounced in relation to low-weight category. Thus, caution is needed when using BMI as a parameter for the diagnosis of nutritional status of children.