Prediction of cardiovascular disease by metabolic syndrome in individuals aged over 40 yrs according to the ATP III and IDF definition: Tehran Lipid and Glucose Study

Different results have been reported on the association between metabolic syndrome (MS) and cardiovascular diseases (CVD). The aim of this study is to determine the role of the Adult Treatment Cholesterol Program (ATP III) and International Diabetes Federation (IDF) definitions of metabolic syndrome in predicting CVD. In this cohort study, all individuals aged over 40 yrs, phase I participants of the TLGS, with no histories of CVD were selected. Based on the APT III and IDF criteria of the MS syndrome, they were divided into those with and those without the condition. All of the subjects were followed for a mean duration of 4.9±0.8 years for occurrence of CVD. The predictive ability of different definitions of the MS was evaluated in different regression models that included only the MS (model 1) and were also adjusted for age, sex, family history of premature CVD and smoking (model 2), serum LDL (model 3) and other components of the MS (model 4). There were 3777 individuals’ aged 54±10 years 1536 (41%) where normal according to the both criteria of the MS and 1714 (45%) and 1900 (50%) subjects had MS according to the ATP III and IDF criteria respectively. New CVD occurred in 143 individuals (3.7%). In our study, the MS was the predictor of CVD in the first three models according to ATP III and IDF criteria however, in model 4, none of the definitions of MS predicted CVD. After calculation of the area under the curve (AUC) for model 2 and 3, it was observed that the power of the ATP III criteria in model 2 for prediction of CVD was significantly higher than the IDF (AUC 0.760 vs. 0.735, p<0.001) but no significant difference was observed between the 2 criteria in model 3. The ATP III and IDF definitions of the MS, it seems can similarly predict CVD after adjustment for the common CVD risk factors and LDL, whereas neither of the 2 definitions had this predictive power after adjustment of their components in addition to the earlier mentioned ones.