Screening for optimal obesity index and its cutoff value for prediction of hypertension

Objective To explore an optimal obesity index and to calculate the cutoff value for prevention and control of hypertension.Methods By using stratified cluster random sampling method,a total of 5 817 adults aged 20-69 years in Shenyang,Dandong and Chaoyang city in Liaoning province were selected from the participants of China's National Physical Fitness Surveillance in 2010.Physical examination was conducted.The obesity indexes were identified by fitting the logistic regression model.The receiver operating characteristic curve(ROC)analysis was performed to compare the predictive effects of waist-to-stature ratio(WSR),waist circumference,body mass index(BMI),waist-to-hip ratio,abdominal skinfold and conicity index.The optimal cutoff value was determined by maximal Youden's index.Results Among the adults,the prevalence of hypertension was 24.9%.The prevalence in men(31.6%)was significantly different from that in the women(18.3%)(χ²=136.7,P<0.001).Results of logistic regression showed that WSR and BMI were obesity indexes for predicting hypertension.The β coefficients for WSR(men:0.50,women:0.58)were all higher than those of BMI(men:0.23,women:0.20)in both men and women.Compared to other obesity indexes,WSR had the highest area under the ROC curve(AUC)(men:0.67,95% confidence interval(95%CI)=0.65-0.69;women:0.72,95%CI=0.70-0.75),and the AUC in women was significantly higher than in men(P<0.05).The cutoff value of WSR for predicting hypertension was 0.50 in men and 0.49 in women.Risks of development of hypertension in the adults with WSR above the cutoff values were 2.62 times(95%CI=2.22-3.09)in men and 4.51 times(95%CI=3.62-5.61)in women than those under the cutoff values.Conclusion WSR is the optimal obesity index to predict hypertension for adults aged 20-69 years,especially for women.