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Coronary Artery Calcium Score vs. Age and Cardiovascular Risk
Study Questions:
What is the predictive ability of coronary artery calcium (CAC) score versus age for incident atherosclerotic cardiovascular disease (ASCVD)?
Methods:
The investigators conducted an analysis of pooled US population-based studies, including the Framingham Heart Study, the Multi-Ethnic Study of Atherosclerosis, and the Cardiovascular Health Study. Results were compared with two European cohorts, the Rotterdam Study and the Heinz Nixdorf Recall Study. Participants underwent CAC scoring between 1998 and 2006 using cardiac computed tomography. The participants included adults older than 60 years without known ASCVD at baseline. CAC scores were assessed. The main outcome measures were incident ASCVD events including coronary heart disease (CHD) and stroke. Cox proportional hazards models were used to examine the predictive ability of CAC score for cardiovascular outcomes.
Results:
The study included 4,778 participants from three US cohorts, with a mean age of 70.1 years; 2,582 (54.0%) were women, and 2,431 (50.9%) were nonwhite. Over 11 years of follow-up (44,152 person-years), 405 CHD and 228 stroke events occurred. CAC score (vs. age) had a greater association with incident CHD (C statistic, 0.733 vs. 0.690; C statistics difference, 0.043; 95% confidence interval [CI] of difference, 0.009-0.075) and modestly improved prediction of incident stroke (C statistic, 0.695 vs. 0.670; C statistics difference, 0.025; 95% CI of difference, −0.015 to 0.064). Adding CAC score to models including traditional CVD risk factors, with only age being removed, provided improved discrimination for incident CHD (C statistic, 0.735 vs. 0.703; C statistics difference, 0.032; 95% CI of difference, 0.002-0.062), but not for stroke. CAC score was more likely than age to provide higher category-free net reclassification improvement among participants who experienced an ASCVD event (0.390; 95% CI, 0.312-0.467 vs. 0.08; 95% CI −0.001 to 0.181) and to result in more accurate reclassification of risk for ASCVD events among these individuals. The findings were similar in the two European cohorts (n = 4,990).
Conclusions:
The authors concluded that CAC may be an alternative marker besides age to better discriminate between lower and higher CHD risk in older adults.
Perspective:
This study, based on results from a pooled individual participant data analysis from three US cohorts comprising older adults (≥60 years) without known CVDs at baseline, reports that CAC score instead of age had a greater association with incident CHD and a modest association with stroke. Furthermore, traditional CVD risk factors with CAC score and without age provided improved discrimination for incident CHD and modest discrimination for stroke. Additional clinical studies are needed to assess whether CAC score can help modify treatment decisions including statin therapy and thereby reduce medical expenses and adverse effects of statins and optimize treatment efficiency in older adults.
Keywords: Atherosclerosis, Cardiac Imaging Techniques, Cardiovascular Diseases, Coronary Artery Disease, Dyslipidemias, Geriatrics, Hydroxymethylglutaryl-CoA Reductase Inhibitors, Outcome Assessment, Health Care, Plaque, Atherosclerotic, Primary Prevention, Risk Factors, Stroke, Tomography, Vascular Diseases
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