title: Carotid intima-media thickness and presence or absence of plaque improves prediction of coronary heart disease risk: the ARIC (Atherosclerosis Risk In Communities) study.
abstract: OBJECTIVE
  We evaluated whether carotid intima-media thickness (CIMT) 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. On an ultrasound scan, CIMT and presence of plaque are associated with CHD, and therefore could potentially help improve CHD risk prediction.
  
  
  METHODS
  Risk prediction models (overall, and in men and women) considered included TRF only, TRF plus CIMT, TRF plus plaque, and TRF plus CIMT plus 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 subjects reclassified was determined. Observed events were compared with expected events, and the net reclassification index was calculated.
  
  
  RESULTS
  Of 13,145 eligible subjects (5,682 men, 7,463 women), approximately 23% were reclassified by adding CIMT plus plaque information. Overall, the CIMT plus TRF plus plaque model provided the most improvement in AUC, which increased from 0.742 (TRF only) to 0.755 (95% confidence interval for the difference in adjusted AUC: 0.008 to 0.017) in the overall sample. Similarly, the CIMT plus TRF plus plaque model had the best net reclassification index of 9.9% in the overall population. Sex-specific analyses are presented in the manuscript.
  
  
  CONCLUSIONS
  Adding plaque and CIMT to TRF improves CHD risk prediction in the ARIC (Atherosclerosis Risk In Communities) study.
authors.affiliation: Section of Atherosclerosis and Vascular Medicine, Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA. vnambi@bcm.tmc.edu
authors.forename: Vijay
authors.initials: V
authors.lastname: Nambi
authors.forename: Lloyd
authors.initials: L
authors.lastname: Chambless
authors.forename: Aaron R
authors.initials: AR
authors.lastname: Folsom
authors.forename: Max
authors.initials: M
authors.lastname: He
authors.forename: Yijuan
authors.initials: Y
authors.lastname: Hu
authors.forename: Tom
authors.initials: T
authors.lastname: Mosley
authors.forename: Kelly
authors.initials: K
authors.lastname: Volcik
authors.forename: Eric
authors.initials: E
authors.lastname: Boerwinkle
authors.forename: Christie M
authors.initials: CM
authors.lastname: Ballantyne
mesh_terms: D050197:Atherosclerosis / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging*; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging*; D016001:Confidence Intervals; D003324:Coronary Artery Disease / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D016016:Proportional Hazards Models; D012372:ROC Curve; D012111:Residence Characteristics; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D017539:Tunica Intima / Q000000981:diagnostic imaging*; D014463:Ultrasonography; D014481:United States / Q000453:epidemiology