Dataset Information

Carotid intima-media thickness is greater but carotid plaque prevalence is lower in black compared with white subjects.

ABSTRACT:

Background and purpose

Carotid IMT is widely used as a surrogate marker for atherosclerosis. Prospective studies in largely white populations demonstrate that it is strongly associated with carotid plaque and is an independent predictor of stroke. There are few data from black populations. In a previous study, we showed that carotid IMT is increased in black individuals in the UK. The purpose of this study was to confirm this with a larger sample size and to establish whether raised IMT in black stroke-free individuals is associated with increased carotid plaque.

Materials and methods

High-resolution sonography was used to measure the CCA-, BIF-, and ICA-IMT and plaque in 306 black and 281 white healthy individuals recruited by random community sampling from London, U.K. Mean CCA-IMT was determined by using a semiautomated computer program that detects the blood/intima borderline and the media/adventitia borderline with the use of a gray-value algorithm.

Results

CCA-IMT was higher in black compared with white individuals after controlling for cardiovascular risk factors and socioeconomic status (β = 0.050; 95%CI, 0.024-0.076; P < .001). BIF- and ICA-IMT were also increased in black subjects. In contrast, carotid plaque was more common in white individuals (OR, 2.90; 95%CI, 1.41-5.96; P = .004).

Conclusions

The lack of correlation between increased IMT and carotid plaque in black individuals implies that IMT should not currently be used as a surrogate marker of atherosclerosis in black populations. It suggests that the increased IMT seen in black individuals may not represent early atherosclerosis.

SUBMITTER: Mackinnon AD

PROVIDER: S-EPMC7964013 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundIntima-media thickness of the walls of the common carotid artery and internal carotid artery may add to the Framingham risk score for predicting cardiovascular events.MethodsWe measured the mean intima-media thickness of the common carotid artery and the maximum intima-media thickness of the internal carotid artery in 2965 members of the Framingham Offspring Study cohort. Cardiovascular-disease outcomes were evaluated for an average follow-up of 7.2 years. Multivariable Cox proportional-hazards models were generated for intima-media thickness and risk factors. We evaluated the reclassification of cardiovascular disease on the basis of the 8-year Framingham risk score category (low, intermediate, or high) after adding intima-media thickness values.ResultsA total of 296 participants had a cardiovascular event. The risk factors of the Framingham risk score predicted these events, with a C statistic of 0.748 (95% confidence interval [CI], 0.719 to 0.776). The adjusted hazard ratio for cardiovascular disease with a 1-SD increase in the mean intima-media thickness of the common carotid artery was 1.13 (95% CI, 1.02 to 1.24), with a nonsignificant change in the C statistic of 0.003 (95% CI, 0.000 to 0.007); the corresponding hazard ratio for the maximum intima-media thickness of the internal carotid artery was 1.21 (95% CI, 1.13 to 1.29), with a modest increase in the C statistic of 0.009 (95% CI, 0.003 to 0.016). The net reclassification index increased significantly after addition of intima-media thickness of the internal carotid artery (7.6%, P<0.001) but not intima-media thickness of the common carotid artery (0.0%, P=0.99). With the presence of plaque, defined as intima-media thickness of the internal carotid artery of more than 1.5 mm, the net reclassification index was 7.3% (P=0.01), with an increase in the C statistic of 0.014 (95% CI, 0.003 to 0.025).ConclusionsThe maximum internal and mean common carotid-artery intima-media thicknesses both predict cardiovascular outcomes, but only the maximum intima-media thickness of (and presence of plaque in) the internal carotid artery significantly (albeit modestly) improves the classification of risk of cardiovascular disease in the Framingham Offspring Study cohort. (Funded by the National Heart, Lung, and Blood Institute.).