title: Associations of Coronary Heart Disease with Common Carotid Artery Near and Far Wall Intima-Media Thickness: The Multi-Ethnic Study of Atherosclerosis.
abstract: BACKGROUND
  Intima-media thickness (IMT) measured on ultrasound images of the common carotid artery (CCA) is associated with cardiovascular risk factors and events. Given the physics of ultrasound, CCA far wall IMT measurements are favored over near wall measurements, but this theoretical advantage is not well studied.
  
  
  METHODS
  A total of 6,606 members of the Multi-Ethnic Study of Atherosclerosis, a longitudinal cohort study (mean age, 62.1 years; 52.7% women) who had near wall and far wall CCA IMT measurements. Multivariate linear regression models were used to estimate model goodness of fit of Framingham risk factors with near wall IMT, far wall IMT, and combined mean IMT. Multivariate Cox proportional hazards models were used to estimate hazard ratios for incident coronary heart disease events for each IMT variable. Change in Harrell's C statistic was used to compare the incremental value of each IMT variable when added to Framingham risk factors.
  
  
  RESULTS
  Mean IMT had the strongest association with risk factors (R(2) = 0.31), followed by near wall (R(2) = 0.26) and far wall (R(2) = 0.22) IMT. Far wall IMT improved the prediction of coronary artery disease events over the Framingham risk factors (change in C statistic, 0.012; 95% CI, 0.006-0.017; P < .001), as did mean IMT (P = .004), but near wall IMT did not.
  
  
  CONCLUSIONS
  Far wall CCA IMT showed the strongest association with incident coronary heart disease, whereas mean IMT had the strongest associations with risk factors. This difference might affect the selection of appropriate IMT variables in different studies.
authors.affiliation: Ultrasound Reading Center, Tufts Medical Center, Tufts University School of Medicine, Boston, Massachusetts. Electronic address: jpolak@tuftsmedicalcenter.org.
authors.forename: Joseph F
authors.initials: JF
authors.lastname: Polak
authors.affiliation: Department of Epidemiology, Johns Hopkins University, Baltimore, Maryland.
authors.forename: Moyses
authors.initials: M
authors.lastname: Szklo
authors.affiliation: Department of Radiology, Saint Elizabeth's Medical Center, Tufts University School of Medicine, Boston, Massachusetts.
authors.forename: Daniel H
authors.initials: DH
authors.lastname: O'Leary
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D050197:Atherosclerosis / Q000000981:diagnostic imaging* / Q000208:ethnology / Q000503:physiopathology; D002340:Carotid Artery Diseases / Q000150:complications / Q000000981:diagnostic imaging* / Q000208:ethnology; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging* / Q000503:physiopathology; D059168:Carotid Intima-Media Thickness; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000208:ethnology / Q000209:etiology; D005006:Ethnicity; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009017:Morbidity / Q000639:trends; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods*; D014481:United States / Q000453:epidemiology
keywords: Carotid artery bifurcation; Common carotid artery; Coronary heart disease; Intima-media thickness; Risk factors; Ultrasound