Screening for coronary heart disease (CHD) among individuals at low risk of the condition is associated with increased use of medications (such as aspirin and statins) and increased additional testing, but no difference in cardiac events at 18 months, according to a report posted online today that will be published in the August 8 print issue of Archives of Internal Medicine, one of the JAMA/Archives journals. The article is part of the journal's Less Is More series.
Coronary heart disease is associated with atherosclerosis, a process in which plaque builds up in the lining of the arteries. More than half of deaths attributed to CHD occur in people who have no signs of heart trouble, according to background information in the article. Coronary computed tomographic angiography (CCTA), a test that uses X-rays to provide a clear look at the heart and arteries, has been suggested as a tool for screening low-risk patients for CHD. "Given the potential for more widespread use of CCTA in cardiac risk evaluation, we sought to evaluate the downstream implications of CCTA testing," write the authors.
John W. McEvoy, M.B., B.Ch., B.A.O., M.R.C.P.I., from Johns Hopkins Ciccarone Center for the Prevention of Heart Disease, Baltimore, and colleagues studied the effect of CCTA in patients who were not at high risk for CHD. From a health screening program conducted at Seoul National University Bundang Hospital in Seoul, South Korea, they selected 1,000 patients who had chosen to undergo CCTA testing and 1,000 patients who did not; neither group had CHD symptoms. At three months and 18 months later, the researchers examined medication use, secondary test referrals, surgical restoration of the blood supply (revascularization) and cardiovascular incidents.
Among the group that had been screened, 215 patients (21 percent) tested positive for signs of atherosclerosis. Those patients were more likely to receive prescriptions for medication at the initial visit and subsequently more likely to undergo further testing and take aspirin and cholesterol-lowering statin drugs during the follow-up period. Patients who had been screened by CCTA were more likely to undergo revascularization, but not to experience cardiovascular events; by 18 months, one such incident had occurred in both the screened and the unscreened groups.
The authors concluded that "physicians and patients may dramatically change practice based on CCTA findings," and call for further study of the implications of this shift, especially in patients at higher risk of CHD. They also point out that the increase in preventive interventions in patients with positive CCTA results did not appear to significantly reduce the risk of cardiovascular incidents, when compared with patients who did not undergo CCTA testing. "Thus," they conclude, "the potential benefit of increased medication use in the CCTA group is tempered by the risk of further testing in low-risk patients without any evidence-based indication."
(Arch Intern Med. 2011;10.1001/archinternmed.2011.204. Available pre-embargo to the media at www.jamamedia.org.)
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Commentary: The Relative Merits of Screening Low-Risk Populations for CHD
The study provides a much-needed perspective of the value of widespread screening versus the risk of diagnosing conditions in people who might never go on to develop illness, according to Michael S. Lauer, M.D., from the National Heart, Lung, and Blood Institute, Bethesda, Md. "Overdiagnosis is a serious problem because it leads to a number of harms, while by its very nature it cannot offer benefit," he writes in commentary accompanying the article. "Physicians cannot easily ignore diagnoses made with screening tests because it is impossible for them to determine whether their patients have real disease or pseudodisease." Lauer urges large-scale trials to determine which groups are at highest risk for health problems, as those individuals would be most likely to benefit from screening. "Given the high prevalence and fears associated with coronary heart disease, the stakes could not be higher," he says.