Prospective Study of Optimal Obesity Index Cut-Off Values for Predicting Incidence of Hypertension in 18–65-Year-Old Chinese Adults

BACKGROUND Overweight and obesity increase the risk of elevated blood pressure; most of the studies that serve as a background for the debates on the optimal obesity index cut-off values used cross-sectional samples. The aim of this study was to determine the cut-off values of anthropometric markers for detecting hypertension in Chinese adults with data from prospective cohort. METHODS This study determines the best cut-off values for the obesity indices that represent elevated incidence of hypertension in 18-65-year-old Chinese adults using data from the China Health and Nutrition Survey (CHNS) 2006-2011 prospective cohort. Individual body mass index (BMI), waist circumference (WC), waist:hip ratio (WHR) and waist:stature ratio (WSR) were assessed. ROC curves for these obesity indices were plotted to estimate and compare the usefulness of these obesity indices and the corresponding values for the maximum of the Youden indices were considered the optimal cut-off values. RESULTS Five-year cumulative incidences of hypertension were 21.5% (95% CI: 19.4-23.6) in men and 16.5% (95% CI: 14.7-18.2) in women, and there was a significant trend of increased incidence of hypertension with an increase in BMI, WC, WHR or WSR (P for trend < 0.001) in both men and women. The Youden index indicated that the optimal BMI, WC, WHR, WSR cut-off values were 23.53 kg/m2, 83.7 cm, 0.90, and 0.51 among men. The optimal BMI, WC, WHR, WSR cut-off values were 24.25 kg/m2, 79.9 cm, 0.85 and 0.52 among women. CONCLUSIONS Our study supported the hypothesis that the cut-off values for BMI and WC that were recently developed by the Working Group on Obesity in China (WGOC), the cut-off values for WHR that were developed by the World Health Organization (WHO), and a global WSR cut-off value of 0.50 may be the appropriate upper limits for Chinese adults.