BACKGROUND: The impact of the metabolic syndrome among populations in the Middle East region is unknown; we therefore examined the association between the syndrome and the risk of ischemic heart disease (IHD) in an Iranian population. METHODS AND RESULTS: The Isfahan Cohort Study (ICS) prospectively followed 6146 Iranian people (51.8% women, aged 35-75 years) from three cities and their rural districts who were initially free of ischemic heart disease. During the 5 year follow-up, 209 (56% men) cases of ischemic heart disease were detected. The metabolic syndrome was defined by the modified criteria of the National Cholesterol Education Program Adult Treatment Panel III (NCEP/ATPIII). End points were defined as fatal and nonfatal myocardial infarction, sudden cardiac death and unstable angina. A clear dose-response relationship was found between the number of metabolic risk factors and the incidence of IHD, with the hazard ratios increasing dose-dependently from 1.72 (95% CI 0.86-3.46) for only one to 1.97 (1.00-3.90), 2.85 (1.45-5.58) and 4.44 (2.25-8.76) for 2, 3 and ≥4 metabolic syndrome component respectively, relative to those with no component. The adjusted hazard ratio (95% CI) associated with the metabolic syndrome was 1.58 (1.06-2.35) in men and 1.72 (1.08-2.74) in women for IHD. The contribution of metabolic syndrome to the IHD risk was particularly strong among smokers although there was no significant interaction. CONCLUSIONS: The metabolic syndrome by NCEP/ATPIII definition is a major determinant of ischemic heart disease in this middle-aged Iranian population, especially among smokers.
BACKGROUND: The impact of the metabolic syndrome among populations in the Middle East region is unknown; we therefore examined the association between the syndrome and the risk of ischemic heart disease (IHD) in an Iranian population. METHODS AND RESULTS: The Isfahan Cohort Study (ICS) prospectively followed 6146 Iranian people (51.8% women, aged 35-75 years) from three cities and their rural districts who were initially free of ischemic heart disease. During the 5 year follow-up, 209 (56% men) cases of ischemic heart disease were detected. The metabolic syndrome was defined by the modified criteria of the National Cholesterol Education Program Adult Treatment Panel III (NCEP/ATPIII). End points were defined as fatal and nonfatal myocardial infarction, sudden cardiac death and unstable angina. A clear dose-response relationship was found between the number of metabolic risk factors and the incidence of IHD, with the hazard ratios increasing dose-dependently from 1.72 (95% CI 0.86-3.46) for only one to 1.97 (1.00-3.90), 2.85 (1.45-5.58) and 4.44 (2.25-8.76) for 2, 3 and ≥4 metabolic syndrome component respectively, relative to those with no component. The adjusted hazard ratio (95% CI) associated with the metabolic syndrome was 1.58 (1.06-2.35) in men and 1.72 (1.08-2.74) in women for IHD. The contribution of metabolic syndrome to the IHD risk was particularly strong among smokers although there was no significant interaction. CONCLUSIONS: The metabolic syndrome by NCEP/ATPIII definition is a major determinant of ischemic heart disease in this middle-aged Iranian population, especially among smokers.