Appropriate Cut-off Values of Anthropometric Variables in Predicting a 7.6-year Risk of Cardiovascular Disease in Iranian Adult Population

Background: TTo determine cutoff points of anthropometric variables for predicting incident cardiovascular disease in Iranian adults.

Methods: In this cohort study, 1614 men and 2006 women, aged ≥ 40 years, participants of the Tehran Lipid and Glucose Study, who were free of cardiovascular disease at baseline, were followed for the mean of 7.6 years. Body mass index (BMI), waist circumference (WC), waist to hip ratio (WHR), waist to height ratio (WHtR) and cardiovascular risks were assessed. Incident cardiovascular disease was ascertained. The adjusted hazard ratios (HRs) for cardiovascular disease were calculated for one standard deviation (SD) change in all obesity variables using Cox proportional hazards regression analysis. Receiver operator characteristic (ROC) curve analysis was used as the method of defining the optimal point if each variable as a predictor of cardiovascular disease.

Findings: We found 333 cardiovascular disease events during follow up. The risk factor adjusted HRs were significant for all anthropometric variables in males and waist to hip ratio in females and were 1.19, 1.24, 1.21 and 1.24 for body mass index, waist circumference, waist to hip ratio and waist to height ratio in males and 1.27 for waist to hip ratio in females, respectively (all P < 0.05). Receiver operator characteristic analysis showed the highest area under curve (AUC) for waist to hip ratio, waist to height ratio and waist circumference, followed by body mass index in males and both genders aged ≤ 60 years. In females, waist to hip ratio and waist to height ratio had the highest AUC, followed by waist circumference and body mass index. Among men and women > 60 years, all the anthropometric variables showed same cardiovascular disease predicting power. The optimal cut off values for cardiovascular disease prediction in males and females aged ≤ 60 years were; body mass indices 26.95 and 29.84 kg/m2, waist circumferences 94.5 and 90.5 cm, waist to hip ratios 0.95 and 0.89, and waist to height ratio 0.55 and 0.60, respectively.

Conclusion: There was no difference between central obesity variables in predicting cardiovascular disease in males, whereas in females waist to hip ratio and waist to height ratio were more appropriate. The cutoff values of anthropometric variables were higher in the Iranian than other Asian populations.

Keywords: Obesity variables, Waist circumference, Body mass index, Cardiovascular disease.