Waist circumference as screening instrument for cardiovascular disease risk factors in schoolchildren

Objective: To propose cutoff points for waist circumference of schoolchildren for the identification of cardiovascular disease risk factors. Methods: This school-based cross-sectional study surveyed 1,413 schoolchildren aged 7 to 12 years old, selected by random cluster sampling. Waist circumference, total cholesterol and systolic and diastolic pressures were measured. Reference values for cardiovascular disease risk factors were developed from measures of total cholesterol and systolic and diastolic blood pressures. The receiver operating characteristic (ROC) curve and bivariate analysis, followed by calculation of sensitivity, specificity and odds ratio, were used in data analysis. Results: The cutoff points had area values under the ROC curve ranging between 0.603 and 0.949, while sensitivity and specificity ranged between 0.500 and 1.00. Among all proposals analyzed, the one presented by this study best balanced sensitivity and specificity values. Bivariate analysis followed by odds ratios calculation indicated that subjects with waist circumference above the proposed cutoff points have increased chances of presenting cardiovascular disease risk factors. Conclusions: The cutoff points proposed in the present study seem to be a valid alternative and better balance sensibility and specificity than other proposals for screening students with increased chances of presenting cardiovascular disease risk factors.