title: What do carotid intima-media thickness and plaque add to the prediction of stroke and cardiovascular disease risk in older adults? The cardiovascular health study.
abstract: BACKGROUND
  The aim of this study was to evaluate whether the addition of ultrasound carotid intima-media thickness (CIMT) measurements and risk categories of plaque help predict incident stroke and cardiovascular disease (CVD) in older adults.
  
  
  METHODS
  Carotid ultrasound studies were recorded in the multicenter Cardiovascular Health Study. CVD was defined as coronary heart disease plus heart failure plus stroke. Ten-year risk prediction Cox proportional-hazards models for stroke and CVD were calculated using Cardiovascular Health Study-specific coefficients for Framingham risk score factors. Categories of CIMT and CIMT plus plaque were added to Framingham risk score prediction models, and categorical net reclassification improvement (NRI) and Harrell's c-statistic were calculated.
  
  
  RESULTS
  In 4,384 Cardiovascular Health Study participants (61% women, 14% black; mean baseline age, 72 ± 5 years) without CVD at baseline, higher CIMT category and the presence of plaque were both associated with higher incidence rates for stroke and CVD. The addition of CIMT improved the ability of Framingham risk score-type risk models to discriminate cases from noncases of incident stroke and CVD (NRI = 0.062, P = .015, and NRI = 0.027, P < .001, respectively), with no further improvement by adding plaque. For both outcomes, NRI was driven by down-classifying those without incident disease. Although the addition of plaque to CIMT did not result in a significant NRI for either outcome, it was significant among those without incident disease.
  
  
  CONCLUSIONS
  In older adults, the addition of CIMT modestly improves 10-year risk prediction for stroke and CVD beyond a traditional risk factor model, mainly by down-classifying risk in those without stroke or CVD; the addition of plaque to CIMT adds no statistical benefit in the overall cohort, although there is evidence of down-classification in those without events.
authors.affiliation: Hackensack University Medical Center, Hackensack, New Jersey. Electronic address: jgardin@hackensackumc.org.
authors.forename: Julius M
authors.initials: JM
authors.lastname: Gardin
authors.affiliation: University of Washington, Seattle, Washington.
authors.forename: Traci M
authors.initials: TM
authors.lastname: Bartz
authors.affiliation: Tufts Medical Center, Boston, Massachusetts; Tufts Medical School, Boston, Massachusetts.
authors.forename: Joseph F
authors.initials: JF
authors.lastname: Polak
authors.affiliation: Tufts Medical School, Boston, Massachusetts.
authors.forename: Daniel H
authors.initials: DH
authors.lastname: O'Leary
authors.affiliation: University of California, Irvine, Irvine, California.
authors.forename: Nathan D
authors.initials: ND
authors.lastname: Wong
mesh_terms: D000368:Aged; D002318:Cardiovascular Diseases / Q000000981:diagnostic imaging / Q000401:mortality*; D059168:Carotid Intima-Media Thickness / Q000706:statistics & numerical data*; D016893:Carotid Stenosis / Q000000981:diagnostic imaging* / Q000401:mortality*; D015897:Comorbidity; D005260:Female; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D020521:Stroke / Q000000981:diagnostic imaging / Q000401:mortality*; D015996:Survival Rate
keywords: Aging; Cardiovascular disease; Carotid arteries; Risk factors; Stroke