Wednesday, April 15, 2009

Asymptomatic diabetics don't need cardiac screening

By Megan Rauscher

NEW YORK , 15 april 2009- In adults with type 2 diabetes and no symptoms of coronary artery disease, routine screening for signs of heart disease does not appear to affect the overall cardiac outcomes and, therefore, "cannot be advocated," researchers conclude in the Journal of the American Medical Association.

While coronary artery disease is a major cause of illness and death in patients with type 2 diabetes, the value of screening asymptomatic patients is controversial, Dr. Frans J. Th. Wackers, of Yale University School of Medicine, New Haven, Connecticut, and colleagues note.

In JAMA this week, they present results of the prospective Detection of Ischemia in Asymptomatic Diabetics (DIAD) study, involving 1123 type 2 diabetics, ages 50 to 65 years, with normal electrocardiograms, no known heart disease and no symptoms of coronary artery disease. The patients were randomly assigned to coronary artery disease screening using adenosine-stress radionuclide myocardial perfusion imaging (MPI), which provides fairly accurate results or no screening.

According to the researchers, the cumulative cardiac event rate was low -- 2.9 percent over an average follow-up of 4.8 years for an average of 0.6 percent per year -- and was not significantly reduced by MPI screening for signs of heart attack.

During 5 years of follow-up, there were 7 nonfatal heart attacks and 8 cardiac-related deaths (2.7 percent) in the screening group and 10 nonfatal heart attacks and 7 cardiac deaths (3.0 percent) in the group that did not undergo screening.

Within this population of patients with type 2 diabetes and no coronary artery disease symptoms, the "use of MPI screening had no discernible effect on subsequent cardiac events," Wackers and colleagues report.

Of those in the screened group, 409 (78 percent) had normal MPI results and 113 (22 percent) had abnormal results. While significant MPI abnormalities on screening were associated with a greater incidence of cardiac events, the positive predictive value of such abnormalities was low (12 percent) and events also occurred in patients with normal screening tests, the researchers found.

Based on the findings of the DIAD study, Wackers said during a JAMA briefing: "In patients with no known coronary artery disease, routine screening for silent coronary artery disease is not to be recommended for four reasons: the yield of screening would be relatively low; the event rate is very low; screening has no effect on the outcome; and obviously, if routine screening was to be used in the United States for 20 or so million patients with diabetes it would be prohibitively expensive."

Wackers and colleagues suggest in their report that "rather than viewing this study as a negative screening study, clinicians might consider the results as a positive message: patients with type 2 diabetes without symptoms to suggest coronary artery disease, receiving contemporary medical care, close follow-up, and appropriate diagnostic evaluation for symptoms of (heart disease) have relatively favorable outcomes in the current era."

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