title: Distribution of coronary artery calcium scores by Framingham 10-year risk strata in the MESA (Multi-Ethnic Study of Atherosclerosis) potential implications for coronary risk assessment.
abstract: OBJECTIVE
  By examining the distribution of coronary artery calcium (CAC) levels across Framingham risk score (FRS) strata in a large, multiethnic, community-based sample of men and women, we sought to determine if lower-risk persons could benefit from CAC screening.
  
  
  BACKGROUND
  The 10-year FRS and CAC levels are predictors of coronary heart disease. A CAC level of 300 or more is associated with the highest risk for coronary heart disease even in low-risk persons (FRS, <10%); however, expert groups have suggested CAC screening only in intermediate-risk groups (FRS, 10% to 20%).
  
  
  METHODS
  We included 5,660 Multi-Ethnic Study of Atherosclerosis participants. The number needed to screen (number of people that need to be screened to detect 1 person with CAC level above the specified cutoff point) was used to assess the yield of screening for CAC. CAC prevalence was compared across FRS strata using chi-square tests.
  
  
  RESULTS
  CAC levels of more than 0, of 100 or more, and of 300 or more were present in 46.4%, 20.6%, and 10.1% of participants, respectively. The prevalence and amount of CAC increased with higher FRS. A CAC level of 300 or more was observed in 1.7% and 4.4% of those with FRS of 0% to 2.5% and of 2.6% to 5%, respectively (number needed to screen, 59.7 and 22.7, respectively). Likewise, a CAC level of 300 or more was observed in 24% and 30% of those with FRS of 15.1% to 20% and more than 20%, respectively (number needed to screen, 4.2 and 3.3, respectively). Trends were similar when stratified by age, sex, and race or ethnicity.
  
  
  CONCLUSIONS
  Our study suggests that in very low-risk individuals (FRS ≤5%), the yield of screening and probability of identifying persons with clinically significant levels of CAC is low, but becomes greater in low- and intermediate-risk persons (FRS 5.1% to 20%).
authors.affiliation: Division of Cardiology, Wayne State University School of Medicine, Detroit, Michigan, USA.
authors.forename: Tochi M
authors.initials: TM
authors.lastname: Okwuosa
authors.forename: Philip
authors.initials: P
authors.lastname: Greenland
authors.forename: Hongyan
authors.initials: H
authors.lastname: Ning
authors.forename: Kiang
authors.initials: K
authors.lastname: Liu
authors.forename: Diane E
authors.initials: DE
authors.lastname: Bild
authors.forename: Gregory L
authors.initials: GL
authors.lastname: Burke
authors.forename: John
authors.initials: J
authors.lastname: Eng
authors.forename: Donald M
authors.initials: DM
authors.lastname: Lloyd-Jones
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002114:Calcinosis / Q000000981:diagnostic imaging / Q000453:epidemiology*; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D015995:Prevalence; D011446:Prospective Studies; D044469:Racial Groups; D018570:Risk Assessment; D012737:Sex Factors; D014057:Tomography, X-Ray Computed; D014481:United States / Q000453:epidemiology