Application of body mass index in prediction of hypertension among children and adolescents in Jiangxi province: a receiver operating characteristic curve analysis

Objective To analyze the area under the receiver operating characteristic(ROC) curve(AUC) for body mass index(BMI) to predict hypertension and to assess the sensitivity and specificity of BMI classification criteria for overweight and obesity screening when applied in prediction of hypertension among Chinese children and adolescents.Methods A total of 5260 students aged 11-17 years were selected with random cluster sampling in Jiangxi province;height, weight and blood pressure were measured and the relationship between BMI and blood pressure were analyzed among the students.The ROC curve for BMI in prediction of hypertension was plotted and the AUC, the sensitivity and specificity of overweight and obesity cut-off points were calculated.Results The AUC for BMI in prediction of hypertension among the boys and girls were 0.590 and 0.563 and both were greater than 0.5(P=0.000).The sensitivity of overweight and obesity cut-off point for the boys were 0.206 and 0.078 and those for the girls were 0.081 and 0.018, and the two sets were both lower than the sensitivity of the optimal cut-off points on the ROC curve(0.551 and 0.433);but the specificity of the overweight and obesity cut-off point for the boys were 0.903 and 0.977 and those for the girls were 0.951 and 0.944, and the two sets were both higher than the specificity of optimal cut-off points on the ROC curve(0.592 and 0.668).Conclusion The specificity of BMI classification criteria for overweight and obesity screening is high when the BMI criteria are applied for predicting hypertension among children and adolescents in Jiangxi province.