Elsevier

Atherosclerosis

Volume 165, Issue 2, 1 December 2002, Pages 285-292
Atherosclerosis

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

https://doi.org/10.1016/S0021-9150(02)00236-8Get rights and content

Abstract

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.

Introduction

Metabolic syndrome (MS) [1], dysmetabolic syndrome or insulin-resistance syndrome [2] (or syndrome X as it was initially designated [3]), which is closely linked to insulin resistance, is a condition which is recognized as raising the risk of cardiovascular disease. It was originally described by Reaven [3] as a quartet of hypertension, glucose intolerance and dyslipidemia (high triglyceride, low high-density lipoprotein-cholesterol (HDL-C)), with insulin resistance or hyperinsulinemia. Central obesity is often associated [4] and other phenotypes, such as impaired fibrinolysis, microalbuminuria, small dense low-density lipoprotein (LDL) particles and markers of acute phase reactants, were later found to be associated [5]. With such an evolving recognition of risk factor clusters, it is not surprising that both the prevalence of MS and its impact on coronary heart disease (CHD) risk in the community were not clearly discernible. The definition used, as well as the population studied, obviously may affect these. The new National Cholesterol Education Program guidelines (Adult Treatment Panel III) [6] recognized MS as a secondary target of risk-reduction therapy and selected to define MS when three or more of certain five risk determinants are present.

It is thus timely to evaluate the prevalence of MS and its significance on CHD risk in populations with high and low levels of LDL-cholesterol (LDL-C). Turkish adults, having essentially low levels of total or LDL-C [7], are a suitable substrate to investigate, particularly in view of a coexisting high prevalence of low HDL-C [8] and anticipatedly of MS [9]. The Turkish population possesses a high prevalence of hypertension (46% of adults aged 30 or over) [10] and a risk factor profile that varies from that of Western populations inasmuch as the relative role of atherogenic lipoprotein phenotype is more pronounced [7]. It is therefore the aim of this study to evaluate prospectively and cross-sectionally (a) the prevalence of MS, (b) the impact (relative and attributable risk) of MS on CHD risk, and (c) the relative roles of the standard MS components and other relevant markers on CHD risk in a population sample representative of middle-aged and elderly Turkish adults.

Section snippets

Study population

Participants in this population-based study form the cohort of the Turkish Adult Risk Factor Study, a prospective survey on the prevalence of cardiac disease and risk factors in adults in Turkey carried out periodically since 1990 in seven geographical regions of the country [11], [12]. Since HDL-C measurements were not performed before the follow-up visit in 1997/98, the latter examination formed the baseline. Further follow-ups were carried out in 2000 and, in half of the cohort, in year

Prospective evaluation

At baseline examination in 1997, 321 men (27% of the sample) and 465 women (38.6%) were identified as having MS. During the follow-up period, 41 deaths from CHD and 85 nonfatal CHD occurred. Coronary deaths developed in 15 individuals with MS (1.9%) as contrasted with 21 in subjects without MS (1.3%). Nonfatal CHD developed in 47 individuals with MS (6.0%) compared to 43 in subjects without MS (2.7%). Overall fatal and nonfatal CHD occurred in 7.9% of participants with MS versus 4.0% without

Discussion

This population-based prospective study sought to assess the predictive value of MS with respect to fatal and nonfatal coronary events in a sample which was representative of the Turkish adult population and had a wide age span, from age 28 years onwards.

Acknowledgments

The financial support of the Turkish Society of Cardiology and of pharmaceutical and nutrition firms in Istanbul (Unilever, Roche, Pfizer, Merck Sharp Dohme, Astra and Bristol Myers-Squibb) is gratefully acknowledged.

References (26)

  • Third Report of the National Cholesterol Education Program (NCEP). Expert panel on detection, evaluation and treatment...
  • A. Onat et al.

    Blood pressure, on prospective analysis the best predictor of coronary mortality in Turkish adults, rose by a mean of over 5/3 mmHg in the past 10 years

    Arch. Turk. Soc. Cardiol.

    (2001)
  • A. Onat et al.

    Plasma lipids and their interrelation in Turkish adults

    J. Epidemiol. Community Health

    (1992)
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