Early adult risk factor levels and subsequent coronary artery calcification: the CARDIA study

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MarilynMann - 13 May 2007 22:56 GMT

Early Adult Risk Factor Levels and Subsequent Coronary Artery
Calcification
The CARDIA Study

Loria et al., J Am Coll Cardiol, doi:10.1016/j.jacc.2007.03.009
(Published online 3 May 2007)

Objectives: We sought to determine whether early adult levels of
cardiovascular risk factors predict subsequent coronary artery calcium
(CAC) better than concurrent or average 15-year levels and independent
of a 15-year change in levels.

Background: Few studies have used multiple measures over the course of
time to predict subclinical atherosclerosis.

Methods: African American and white adults, ages 18 to 30 years, in 4
U.S. cities were enrolled in the prospective CARDIA (Coronary Artery
Risk Development in Young Adults) study from 1985 to 1986. Risk
factors were measured at years 0, 2, 5, 7, 10, and 15, and CAC was
assessed at year 15 (n = 3,043).

Results: Overall, 9.6% adults had any CAC, with a greater prevalence
among men than women (15.0% vs. 5.1%), white than African American men
(17.6% vs. 11.3%), and ages 40 to 45 years than 33 to 39 years (13.3%
vs. 5.5%). Baseline levels predicted CAC presence (C = 0.79) equally
as well as average 15-year levels (C = 0.79; p = 0.8262) and better
than concurrent levels (C = 0.77; p = 0.019), despite a 15-year change
in risk factor levels. Multivariate-adjusted odds ratios of having CAC
by ages 33 to 45 years were 1.5 (95% confidence interval [CI] 1.3 to
1.7) per 10 cigarettes, 1.5 (95% CI 1.3 to 1.8) per 30 mg/dl low-
density lipoprotein cholesterol, 1.3 (95% CI 1.1 to 1.5) per 10 mm Hg
systolic blood pressure, and 1.2 (95% CI 1.1 to 1.4) per 15 mg/dl
glucose at baseline. Young adults with above optimal risk factor
levels at baseline were 2 to 3 times as likely to have CAC.

Conclusions: Early adult levels of modifiable risk factors, albeit
low, were equally or more informative about odds of CAC in middle age
than subsequent levels. Earlier risk assessment and efforts to achieve
and maintain optimal risk factor levels may be needed.

Marilyn

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MarilynMann - 16 May 2007 03:03 GMT

After reading this study, I am feeling a little frustrated. Odds
ratios were reported after adjusting for age, race, gender, and other
risk factors. Why didn't they report odds ratios separately by
gender? After all, CAC was more prevalent in men than in women (15.0%
vs 5.1%). Maybe CAC was too low in women for them to find
statistically significant relationships in subgroups separated by
gender?

I am also wondering why CAC was higher in white men than in African
American men, even though CVD morbidity and mortality is generally
higher in African Americans.

The conclusion to the study is as follows:

"Risk factor levels in 18- to 30-year-old young adults predicted
calcification of plaque in coronary arteries at ages 33 to 45 years
better than concurrent levels, equally as well as average 15-year
levels, and regardless of 15-year change in levels. Thus, early adult
levels of modifiable CVD risk factors, albeit relatively low, may be
more informative than generally recognized by young adults and their
clinicians. Young adults with above-optimal risk factor levels at
baseline, who were 2 to 3 times as likely to have CAC, and those with
family history of CVD, which predicted CAC independently of
established risk factors in the CARDIA study,* could be targeted for
preventive efforts. Waiting until modifiable risk factor levels reach
clinical guideline thresholds to prevent CVD may not be desirable
because plaque calcification is already underway and appears to be
accelerating by ages 40 to 45 years. Earlier risk assessment and
efforts to encourage young adults to achieve and maintain optimal
levels may be needed to prevent or delay coronary calcification, which
has been shown to predict subsequent coronary heart disease."

*Fornage et al., Parental history of stroke and myocardial infarction
predicts coronary artery calcification: The Coronary Artery Risk
Development in Young Adults (CARDIA) study. Eur J Cardiovasc Prev
Rehabil 2004;11:421-6.

* * *
The authors don't specify how they think these early risk factors
should be modified, although they seem to be advocating individual
assessment and treatment rather than population-wide efforts.

The CARDIA study is supported by the National Heart, Lung, and Blood
Institute.

Marilyn

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