Clinical Research
Cardiac Imaging and Risk
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

https://doi.org/10.1016/j.jacc.2010.11.053Get rights and content
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Objectives

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%).

Key Words

atherosclerosis
coronary calcium
coronary heart disease
Framingham risk score
low risk
number needed to screen
population
risk factors

Abbreviations and Acronyms

CAC
coronary artery calcium
CHD
coronary heart disease
FRS
Framingham risk score(s)
NNS
number needed to screen

Cited by (0)

Supported by contracts N01-HC-95159 through N01-HC-95169 from the National Heart, Lung, and Blood Institute, Bethesda, Maryland. Dr. Greenland received an honorarium from GE/Toshiba in 2008. All other authors have reported that they have no relationships to disclose.