Technology has advanced modern medicine but at a cost, both to health care expenditures and to a patient’s long-term health status. For example, imaging techniques that use radiation to provide glimpses of internal structures offer minimally invasive approaches to finding health issues. However, they also expose patients to a small doses of ionizing radiation, including the kind used in X-rays and CT scans, which, in rare cases, can cause cancer down the road.

A team of researchers led by assistant professor Joseph Ladapo of New York University’s Departments of Medicine and Population Health examined whether the trade-offs specifically associated with cardiac stress testing were being adequately considered in decisions to include imaging. They found, in fact, that imaging may be overused, creating unnecessary health care spending and increased risk of cancer in those tested. The results of their study were published in the October 8 issue of the Annals of Internal Medicine.

“The key finding of our study is that cardiac stress testing with imaging has grown briskly over the past two decades in the US, and that about 1 million stress tests with imaging are probably inappropriate,” states Ladapo. “These inappropriate tests cost us about half a billion dollars in healthcare costs annually and lead to about 500 people developing cancer in their lifetime because of radiation they received during that cardiac stress test.”

Cardiac stress tests assess the amount of stress one’s heart can tolerate before it exhibits signs of overburden such as abnormal rhythm or inadequate blood flow within itself. Tests with imaging include the injection of a radioactive tracer into the blood. The tracer emits small amounts of radiation that is then imaged in order to identify areas of compromised blood flow.

Ladapo and colleagues used data on patients with no coronary heart disease who were referred for cardiac stress testing, gathered from the National Ambulatory Medical Care Survey and the National Hospital Ambulatory Medical Care Survey. They compared the number of stress tests ordered with and without imaging in the period 1993 to 1995 with the number with and without imaging in the period 2008 to 2010.

The researchers found that the annual number of cardiac stress tests ordered in the U.S. increased by over 50 percent from 1993–1995 and 2008–2010 and attribute this increase to changes in population and provider characteristics. Cardiac stress tests with imaging comprised 59 percent of the total tests in 1993–1995 compared to 87 percent in 2008–2010. By referencing the most recent appropriate use criteria, the researchers determined that 34.6 percent of the tests done with imaging in 2008–2010 really did not warrant imaging.

Using published methods, the researchers estimate that this overuse of imaging in the period 2008–2010 cost $501 million. They predict, again based on published methods, that 491 future cancer cases will be attributable to inappropriate imaging with cardiac stress testing done in this period.

“Cardiac stress testing is an important clinical tool,” says Dr. Ladapo, “but we are over using imaging for reasons unrelated to clinical need.”

The report comes quickly on the heels of a recent scientific statement by the American Heart Association on improving informed decisions that involve both doctors and patients when it comes to radiation-based imaging. Ladapo and his colleagues also looked for but found no evidence that patient ethnicity plays any significant role in whether a cardiac stress test with imaging is ordered.