Determination of most suitable cut off point of waist circumference for diagnosis of metabolic syndrome in Kerman

Objectives: Metabolic syndrome is a determining indicator of cardiovascular diseases and diabetes.
Abdominal obesity, determined by measuring waist circumference, is one of the most important criteria
for diagnosing this syndrome. This criterion varies between men and women and among different races.
The present study aims at the assessment of the sensitivity and specificity of the commonly used cut off
point of waist circumference, and the estimation of the most suitable cut off point of waist circumference
for the diagnosis of metabolic syndrome in the urban society of Kerman.
Methods: 5332 subjects consisting of 2966 women and 2366 men, 20 years old and above were studied
in a population based, cross sectional study. Waist circumference, blood pressure, blood sugar, and blood
lipids were measured. People with at least two of the NCEP ATP III criteria – high blood pressure
(BP > 130/80), high triglycerides (TG > 150), high glucose (FBG > 100) and low HDL (HDL < 40 in men and <50 in women) – were taken as population at risk. ROC analysis was used for determining the most suitable cut off point of waist circumference. The prevalence of metabolic syndrome was then assessed based on IDF, NCEP criteria and the proposed criterion, and agreement among the three methods in diagnosing people suffering from metabolic syndrome was examined. Results: The average  standard deviation of waist circumference in women and in men was 83.90  12.55 and 87.99  11.94 cm respectively. The most suitable cut off point of waist circumference for metabolic syndrome diagnosis was 86 in women and 89 in men. These circumferences had the highest specificity and sensitivity. The prevalence of metabolic syndrome in IDF, NCPE, and the proposed criterion was 30.4%, 27.7%, and 35.2% respectively. The new criterion and the NCEP criterion achieved the highest agreement (kappa factor = 83%). Conclusion: The cuts off point of waist circumference in men and women are close. It is possible, then, to determine a common cut off point of waist circumference for both in Iran. Therefore, the cut point of 90- cm of waist circumference proposed by the National Obesity Committee seems to be appropriate for the Iranian society. These clinical findings should nevertheless be verified by simulation.