Appropriate BMI cut-off values for identification of metabolic risk factors: Third national surveillance of risk factors of non-communicable diseases in Iran (SuRFNCD-2007)

Aim: To determine the appropriate threshold of body mass index (BMI) associated with increased risk of cardiovascular diseases in a large representative sample of an Iranian population.

Subjects and methods: Data of third national surveillance of risk factors of non-communicable diseases (SuRFNCD-2007) were used in this study. Sensitivity, specificity, and shortest distance on the receiver-operating characteristic (ROC) curves were used to determine gender-specific optimal cut-offs of BMI for cardiometabolic risk factors including elevated blood pressure, low high-density lipoprotein cholesterol, high triglycerides, high fasting plasma glucose and for ≥ 2 of the aforementioned risk factors.

Results: There was a continuous increase in the prevalence of cardiometabolic risk factors with increasing BMI (p < 0.001). At the BMI of 25–29 kg/m² men were at higher risk of cardiovascular diseases compared to women (p < 0.001). The appropriate BMI cut-offs ranged from 24.6–26.1 kg/m² for men and from 26.9–28.8 kg/m² for women. The optimal BMI cut-offs for identifying any two or more of those risk factors were 25.2 and 27.3 kg/m² in men and women, respectively.

Conclusion: In men the appropriate BMI cut-offs are ～25 kg/m², while in women higher BMI values are associated with risk of cardiovascular diseases.