JACC: Calcium CT screening predicts cardiac events in asymptomatic patients

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Image source: GE Healthcare

Coronary artery calcium (CAC) scoring appears to foster efficient selective testing patterns among asymptomatic individuals at risk for cardiovascular disease (CVD), according to the prospective EISNER trial published Sept. 29 in the Journal of the American College of Cardiology.

Leslee J. Shaw, PhD, from Emory University School of Medicine in Atlanta, and colleagues prospectively evaluated procedural costs and resource consumption patterns in the EISNER (Early Identification of Subclinical Atherosclerosis by Noninvasive Imaging Research) study after CAC measurements. Daniel Berman, MD, chief of Cedars Sinai Medical Center in Los Angeles, is the prinicpal investigator of the EISNER trial.

The authors noted that controversy surrounds the expansion of CVD screening to include atherosclerosis imaging because of a concern whether the costs will outweigh any benefit. They noted that “[d]iscussions regarding CVD screening arise at a time when growth in imaging is double that of all other physician services, at an estimated cost of $80 billion annually...Economic evaluations, such as that within EISNER, can then be used to inform healthcare policy decisions.”

The EISNER researchers performed detailed risk factor and CAC measurements with four-year follow-up for CVD death or myocardial infarction and procedures. They also estimated costs associated with the use of Medicare reimbursement rates (discounted and inflation corrected).

Of the 1,381 participants enrolled in this EISNER substudy, a total of 1,361 (98.6 percent) were available for this analysis.

According to the authors, CAC scores varied widely but were skewed toward low scores with 56.7 percent of screened subjects having CAC scores of 10 or less and only 8.2 percent having CAC scores of at least 400.

Shaw and colleagues reported that noninvasive testing was infrequent and medical costs were low among subjects with low CAC scores, both rising progressively with increasing CAC scores, particularly in the 31 (2.2 percent of subjects) that had CAC scores of at least 1,000.

Similarly, the authors said that invasive coronary angiography rose progressively with increasing scores but occurred exclusively among subjects first undergoing noninvasive testing and overall, was performed in only 19.4 percent of subjects with CAC scores of at least 1,000.

Based on their findings, the researchers concluded that CAC scanning is associated with a marked differential in downstream frequency of medical tests and costs, ranging from a very low frequency of testing and invasive procedures among a predominantly large percentage of subjects with low CAC scores, to selectively concentrated testing and procedures among a small number of subjects with CAC scores of more than 400.

They also wrote that their “data reveal that the differential in costs among our study population were substantially wider with CAC scanning compared to costs based on the FRS [Framingham Risk Score]. When compared with noncardiac tests or blood markers, it remains plausible that CAC may also elicit a greater differential in procedural costs and treatment costs when compared with other screening tests, but impact may vary by treatment.”