Adding CACS improves risk classification for coronary heart disease
MedWire News: Patients can be more accurately risk-stratified for the prediction of coronary heart disease (CHD) events if the amount of calcium in their coronary arteries is taken into account alongside traditional risk factors, research suggests.
Philip Greenland (Northwestern University, Chicago, Illinois, USA) and colleagues comment: “The results of this study demonstrate that when coronary artery calcium score (CACS) is added to traditional risk factors, it results in a significant improvement in the classification of risk for the prediction of CHD events in an unsymptomatic population-based sample of men and women drawn from four US racial/ethnic groups.”
Greenland et al explain in the Journal of the American Medical Association that CACS was measured by computed tomography in 6814 participants from the Multi-Ethnic Study of Atherosclerosis, a population-based cohort without known cardiovascular disease. Recruitment spanned July 2000 to September 2002, while follow-up extended through May 2008.
Participants with diabetes were excluded from the primary analysis. Five-year risk estimates for incident CHD were categorized as 0% to less than 3%, 3% to less than 10%, and 10% or more using Cox proportional hazard models. Model 1 used age, gender, tobacco use, systolic blood pressure, antihypertensive medication use, total and high-density lipoprotein cholesterol, and race/ethnicity, while Model 2 used these risk factors plus CACS.
The researchers report that during a median follow-up of 5.8 years, 209 CHD events occurred, of which 122 were myocardial infarction, death from CHD, or resuscitated cardiac arrest.
Model 2 was significantly more accurate than Model 1 in predicting individuals’ risks for CHD events. Model 2, compared with Model 1, saw an additional 23% of those who experienced CHD events reclassified as high risk, and an additional 13% of those who did not experience events reclassified as low risk.
“The results provide encouragement for moving to the next stage of evaluation to assess the use of CACS on clinical outcomes,” say Greenland et al.
In an accompanying editorial, John Ioannidis (Foundation for Research and Technology–Hellas, Ioannina, Greece) and Ioanna Tzoulaki (Imperial College of Medicine, London, UK) commented: “the authors have not yet demonstrated that the added accuracy in risk stratification can actually aid clinicians in better treating patients or improving their clinical outcomes.
“Therefore, their findings, no matter how promising, do not suffice to recommend this marker for widespread routine use.”
In a statement issued by the British Heart Foundation, Ellen Mason, senior cardiac nurse, also makes the point that “introducing widespread calcium scoring for people who have risk factors but no signs of heart disease would need a massive increase in the availability of scanners and the skilled staff needed to use them.”
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By James Taylor