Metabolic syndrome and carotid intima media thickness in the Health 2000 Survey

Abstract

Background and purpose

Metabolic syndrome has been associated with increased carotid intima-media thickness (CIMT) and cardiovascular disease (CVD). The objective of this study was to examine metabolic syndrome as a determinant of CIMT in men and women and to compare the Framingham risk score (FRS) and metabolic syndrome as risk factors for increased carotid atherosclerosis.

Methods

The study population consisted of 1353 Finnish men and women aged 45 years and above who participated in Finnish population-based Health 2000 Survey. CIMT was used as a marker of subclinical atherosclerosis. The National Cholesterol Education Program Adult Treatment Panel III criterion was used to define the presence of metabolic syndrome.

Results

In multivariable models, metabolic syndrome was an independent determinant of CIMT in both sexes (p ≤ 0.001 for both). When metabolic syndrome was included in the regression models along with its components, it was an independent determinant of CIMT in women but not in men. After dividing the population into risk categories according to FRS and the presence of metabolic syndrome, FRS predominantly determined CIMT regardless of the presence of metabolic syndrome in men. In women, however, CIMT was significantly higher in subjects with metabolic syndrome than in those without it, independently of the FRS.

Conclusions

Metabolic syndrome is an independent determinant of CIMT in both sexes. In women but not in men, metabolic syndrome is associated with CIMT independently of its components. Metabolic syndrome provides additional information on a person’s risk for early atherosclerosis beyond FRS in women but not in men.

Introduction

Metabolic syndrome is a cluster of cardiovascular risk factors such as central obesity, hypertension, dyslipidemias and glucose intolerance. It has been shown to be a predictor of type 2 diabetes [1], coronary heart disease (CHD) [2] and mortality [3], [4], [5]. Various definitions of metabolic syndrome have been proposed for clinical use. The National Cholesterol Education Program (NCEP) Adult Treatment Panel III proposed their widely used clinical definition for metabolic syndrome in 2001 [6].

Carotid artery intima-media thickness (CIMT) is a well-established marker of subclinical atherosclerosis that can be measured non-invasively. Increased CIMT has been shown to predict CHD, cerebrovascular disease [7], [8], [9] and cardiovascular mortality [10]. The presence of metabolic syndrome has been linked to increased CIMT in several studies [11], [12], [13], [14], [15], [16]. It has been suggested that metabolic syndrome is a stronger risk factor for subclinical atherosclerosis in women than in men [17]. The data regarding sex differences are, however, limited.

There is an ongoing debate whether metabolic syndrome provides useful information of the patient’s cardiovascular risk in addition to the traditional risk factors. The Framingham risk score (FRS) is a clinical tool for quantifying an individual’s CHD risk [18] based on traditional risk factors. There are few data comparing metabolic syndrome and FRS in their ability to identify subjects with increased CIMT [15], [19], [20]. To the best of our knowledge, possible sex differences regarding this issue have not been studied.

The objective of this study was to find out whether metabolic syndrome associates differently with CIMT in men and women. Furthermore, we set out to discover whether or not metabolic syndrome is a risk factor of CIMT beyond FRS.