Abstract P672: Association of Intima-Media Thickness Measured at the Common-Carotid Artery With Incident Carotid Plaque

Abstract

Background: The association between common-carotid artery intima-media thickness (CCA-IMT) and incident carotid plaque has not been characterised fully. We therefore aimed to precisely quantify the relationship between CCA-IMT and carotid plaque development. Methods: We undertook an individual-participant-data meta-analysis of prospective studies from the Proof-ATHERO consortium that recorded baseline CCA-IMT and incident carotid plaque. We excluded participants with a history of cardiovascular disease or pre-existing carotid plaque at baseline. Incident carotid plaque was defined as the development of first-ever plaque during follow-up in any segment of the carotid artery. We calculated study-specific odds ratios for incident carotid plaque using logistic regression and then combined study-specific estimates using random-effects meta-analysis. Results: We analysed data from 21,494 individuals in 20 studies. Mean baseline age was 56 years (SD 9), 55% were female, and mean baseline CCA-IMT was 0.71 mm (SD 0.17). Over a median follow-up of 5.9 years (5 th -95 th percentile 1.9-19.0), 8,278 individuals developed first-ever carotid plaque. Baseline CCA-IMT was approximately log-linearly associated with the odds of developing carotid plaque. In an analysis adjusted for age, sex, and trial arm, the odds ratio for incident carotid plaque per SD higher baseline CCA-IMT was 1.40 (95% confidence interval 1.31-1.50; I 2 =63.9%). In an analysis further adjusted for ethnicity, smoking, diabetes, body mass index, systolic blood pressure, low-density and high-density lipoprotein cholesterol, and lipid-lowering and antihypertensive medication, the corresponding odds ratio was 1.34 (1.24-1.45; I 2 =59.4%; 14 studies; 16,297 participants; 6,381 incident plaques). We observed no significant effect modification across clinically relevant subgroups including age, sex, lipid-lowering medication, low-density lipoprotein cholesterol, development of cardiovascular disease during follow-up, type of study, and type of CCA-IMT measure. In a sensitivity analysis restricted to studies defining carotid plaque as focal thickening, the odds ratio was similar as in the primary analysis (1.38; 1.29-1.47; I 2 =57.1%; 14 studies; 17,352 participants; 6,991 incident plaques). Conclusions: In this large-scale meta-analysis based on participant-level data, CCA-IMT was associated with the long-term risk of developing first-ever carotid plaque, independent of traditional cardiovascular risk factors. The association was robust across sensitivity analyses and similarly strong for women and men and for individuals at different ages.