Metabolic syndrome: major impact on coronary risk in a population with low cholesterol levels--a prospective and cross-sectional evaluation

The prevalence and the excess coronary heart disease (CHD) risk of the metabolic syndrome (MS) and its components were investigated in the Turkish Adult Risk Factor Study in both a prospective and a cross-sectional manner. In a population sample, representative of Turkish adults who have low levels of high- and low-density lipoprotein-cholesterol (HDL-C and LDL-C), MS was identified in conformity with the definition used in the recent NCEP guidelines. Prospective analysis was based on 2398 men and women (mean age at baseline 49.1+/-13 years) who had a baseline examination in 1997/98 and were followed-up for a mean of 3 years. CHD was diagnosed based on clinical findings and Minnesota coding of resting electrocardiograms. Fatal and nonfatal CHD developed in 126 subjects. 27% of men and 38.6% of women were found to have MS at baseline examination. When adjusted for age, MS was an independent predictor of subsequent overall fatal and nonfatal CHD in both genders, displaying an RR of 1.71. At the final cross-sectional evaluation, coronary risk associated with MS in men was primarily accounted for by standard MS components (largely inherent in glucose intolerance, hypertension and in a surrogate of small, dense LDL particles), in addition to a minor independent contribution by C-reactive protein (CRP). In women with MS, a substantial residual coronary risk remained after controlling for five components, which was partly accounted for by levels of LDL-C and CRP. It was estimated that MS was the culprit in just over half the cases of CHD in Turkey. CONCLUSION: MS was the major determinant of CHD risk in a population having generally low levels of HDL-C and LDL-C in middle-aged and elderly adults, extending to three out of every eight adults, and imposing an overall excess CHD risk of approximately 70%. In contrast to men, a substantial residual coronary risk is retained in Turkish women after controlling for five MS components.