Recent attempts to identify cardiovascular risk factors affecting early-stage carotid atherosclerosis, measured by ultrasonographically assessed intima-media thickness, have been inconclusive.
To study the relationship between traditional cardiovascular risk factors and intima-media thickness.
Ultrasonic evaluation of the intima-media thickness of the common carotid artery was included in the 5-year follow-up examination of participants of the Edinburgh Artery Study. We had valid readings of intima-media thickness for 1106 men and women aged 60-80 years. Information on a range of cardiovascular risk factors had been collected during the baseline examination.
For men, in addition to age, lifetime smoking (measured in terms of pack years) was the only cardiovascular risk factor associated with increased intima-media thickness (P< or = 0.01) in the univariate analysis. Both systolic blood pressure (P < or = 0.001) and the high-density lipoprotein (HDL: total cholesterol ratio (P < or = 0.01) were correlated with intima-media thickness for women. When all the variables had been included in a multivariate analysis, pack years of smoking and the HDL:total cholesterol ratio were associated with early atherosclerotic development in men. In an equivalent analysis for women, alcohol consumption, systolic blood pressure and the HDL:total cholesterol ratio were associated with intima-media thickness.
These data suggest that risk factors affecting intima-media thickness differ for men and women. Further sex-specific analyses of prospective population studies are required in order to clarify the role of 'traditional' cardiovascular risk factors in the early stages of carotid atherosclerosis.
[Show abstract][Hide abstract] ABSTRACT: The well established correlation between intima-media thickness (IMT) and the risk of cardiovascular and cerebrovascular events and death is usually measured in subjects with multiple vascular risk factors, which makes it difficult, after application of the usual analysis-of-variance linear combination of effects model, to establish whether each cardiovascular risk factor has, per se, an effect on IMT.
In this study we investigated five "pure" groups of patients (865), i.e. each presenting only one of the following risk factors: hypertension, obesity, overweight, smoking, hypercholesterolaemia and a control group of 37 healthy subjects. We measured, both as discrete and as continuous variables, the following indices: intima-media thickening of the common carotid artery (IMT(C)) and of the common femoral artery (IMT(F)) and the ankle-brachial index (ABI). Descriptive statistics were used to analyse the prevalence of pathological values for the three indices in the different groups. Subsequently the entire group of 902 subjects was included in a correlation analysis in which the Pearson correlation coefficient for each pair of variables was computed. In order to assign the risk factors a continuous ranking, and obtain a more general idea of the correlation structure, principal component analysis (PCA) was used. The scores obtained from PCA made it possible to build a scale of severity of the vascular risk factors considered. All the risk factors considered were demonstrated to strongly affect the studied indices. Overweight was shown to be the least important risk factor with regard to intima-media thickening, followed by smoking, hypercholesterolaemia, hypertension and finally obesity, which emerged as the greatest risk factor.
The strong correlation between the indices made it possible to compute a composite general score, which provides an univocal risk estimation at single-patient level. IMT(F) was demonstrated to be the most sensitive descriptor. The construction of this risk scale has implications for preventive treatment and the frequency of instrumental examinations, allowing clear quantitative definition of the extent of the damage.
[Show abstract][Hide abstract] ABSTRACT: Background—Increased carotid intimal-medial thickness (IMT) and coronary artery calcification (CAC) are used as 2 markers of early atherosclerosis. Our objectives were to assess whether increased IMT and CAC are related and to determine the relationship between cardiovascular risk factors and carotid IMT in young adults. Methods and Results—A sample of 182 men and 136 women aged 33 to 42 years living in Muscatine, Iowa, underwent B-mode carotid ultrasound to determine the mean of 12 measurements of maximal carotid IMT. CAC was defined as calcification in the proximal coronary arteries in $3 contiguous pixels with a density of $130 HU. The mean IMT was 0.788 mm (SD 0.127) for men and 0.720 mm (SD 0.105) for women. CAC was present in 27% of men and 14% of women and was significantly associated with IMT in men (P,0.025) and women (P,0.005). With multivariate analysis, after adjustment for age, significant risk factors for carotid IMT were LDL cholesterol ( P,0.001) and pack-years of smoking (P,0.05) in men and LDL cholesterol (P,0.001) and systolic blood pressure (P,0.01) in women. These risk factors remained significant after CAC was included in the multivariate model. Conclusions—There is an association between increased carotid IMT and CAC and between cardiovascular risk factors and increased IMT in young adults. Carotid IMT may provide information in addition to CAC that can be used to identify young adults with premature atherosclerosis. (Circulation. 1999;100:838-842.)
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