Carotid Intima-Media Thickness Score, Positive Coronary Artery Calcium Score, and Incident Coronary Heart Disease: The Multi-Ethnic Study of Atherosclerosis

Background-Common carotid artery and internal carotid artery intima-media thicknesses (IMT) are associated with coronary heart disease (CHD) and increase with age. Using age, sex, and race/ethnicity IMT percentiles may improve CHD prediction when added to Framingham risk factors and coronary artery calcium score. We study these possibilities in the Multi-Ethnic Study of Atherosclerosis (MESA), a multi-ethnic cohort of whites, Chinese, blacks, and Hispanics. Methods and Results-IMT data were acquired in the age range 45 to 84 years. Common carotid artery and internal carotid artery IMT, sex, and race/ethnic specific normative values were calculated for each MESA participant and combined as an IMT score. Multivariable Cox-proportional hazards models and logistic regression models were generated with CHD as outcome adding the IMT score to (1) a base model with Framingham risk factors, sex, race/ethnicity and (2) the base model with coronary artery calcium added. Harrell's C-statistics and area under the curve were estimated. Median follow-up was 10.2 years (interquartile range: 9.7, 10.7 years) with 429 first-time CHD events. Mean age was 62.1 years and 52.6% of participants were women. IMT score increased the base area under the curve from 0.7210 to 0.7396 (P=0.0008) and with positive coronary artery calcium score added to the model, from 0.7627 to 0.7714 (P=0.02). Conclusions-A carotid IMT score based on normative data incrementally adds to Framingham risk factors and a positive calcium score in predicting first-time CHD in an ethnically diverse cohort.