Carotid Intima-Media Thickness and Presence or Absence of Plaque Improves Prediction of Coronary Heart Disease Risk

Abstract

STRUCTURED ABSTRACT Objectives We evaluated whether carotid intima-media thickness (C-IMT) and the presence or absence of plaque improved coronary heart disease (CHD) risk prediction when added to traditional risk factors (TRF). Background Traditional CHD risk prediction schemes need further improvement as the majority of the CHD events occur in the “low” and “intermediate” risk groups. C-IMT and presence of plaque on an ultrasound are associated with CHD and therefore could potentially help improve CHD risk prediction. Methods Risk prediction models (overall, in men and women) considered included TRF-only, TRF+C-IMT, TRF+plaque, and TRF+C-IMT+ plaque. Model predictivity was determined by calculating the area under the receiver operating characteristic curve (AUC) adjusted for optimism. Cox-proportional hazards models were used to estimate 10-year CHD risk for each model, and the number of individuals reclassified determined. Observed events were compared with expected events; and, the net reclassification index (NRI) was calculated. Results Of 13,145 eligible individuals (5,682 men; 7,463 women), ~23% were reclassified by adding C-IMT+plaque information. Overall, the addition of C-IMT and plaque separately or together to the TRF model improved the AUC which increased from 0.742 to 0.750, 0.751 and 0.755 for the TRF-only, TRF+C-IMT, TRF+plaque and TRF+C-IMT+plaque model respectively. The C-IMT+TRF+plaque model had a NRI of 9.9% when compared to TRF-only in the overall population. However, comparison of TRF+C-IMT+plaque with TRF+C-IMT or TRF+plaque only resulted in non-significant or modestly significant changes of the various statistical tests. Sex-specific analyses are presented in the manuscript. Conclusion Adding plaque and C-IMT to TRF improves CHD risk prediction in the ARIC study.