High blood pressure in children and its correlation with three definitions of obesity in childhood

Abstract

Background: Several authors have correlated the increase of cardiovascular risk with the nutritional status, however there are different criteria for the classification of overweight and obesity in children.

Objectives: To evaluate the performance of three nutritional classification criteria in children, as definers of the presence of obesity and predictors of high blood pressure in schoolchildren.

Methods: Eight hundred and seventeen children ranging 6 to 13 years old, enrolled in public schools in the municipality of Vila Velha (ES) were submitted to anthropometric evaluation and blood pressure measurement. The classification of the nutritional status was established by two international criteria (CDC/NCHS 2000 and IOTF 2000) and one Brazilian criterion (Conde e Monteiro 2006).

Results: The prevalence of overweight was higher when the criterion of Conde e Monteiro (27%) was used, and inferior by the IOTF (15%) criteria. High blood pressure was observed in 7.3% of children. It was identified a strong association between the presence of overweight and the occurrence of high blood pressure, regardless of the test used (p<0.001). The test showing the highest sensitivity in predicting elevated BP was the Conde e Monteiro (44%), while the highest specificity (94%) and greater overall accuracy (63%), was the CDC criterion.

Conclusions: The prevalence of overweight in Brazilian children is higher when using the classification criterion of Conde e Monteiro, and lower when the criterion used is IOTF. The Brazilian classification criterion proved to be the most sensitive predictor of high BP risk in this sample.

Figure 1

Proportions of children with nutritional status classified as underweight, normal weight, overweight or obese according to criteria established by: CDC 2000, IOTF 2000 and Conde and Monteiro 2006. (* p < 0,001; chi-square test).

Figure 2

Linear regression between Z of Body Mass Index (calculated by reference of CDC 2000) and Z of Systolic BP (A) and diastolic BP (B) (calculated according to the recommendations of the 4^th National Task Force on Hypertension of the National Heart, Lung and Blood Institute 2004).

Figure 3

Average of Z of Systolic BP (A) in accordance to the nutritional classification established by three criteria: CDC 2000, IOTF 2000 and Conde and Monteiro 2006. (* p < 0,001; ns: statistically not significant).