Too Many Stress Tests Involve Unnecessary Exposure to Radiation

Cardiac stress testing can be a useful tool to assess heart function, but since it became trendy for companies to subject their executives to treadmill stress tests as part of their annual checkups, the technology has grown too big for its britches.

That’s paraphrasing the results of a study published recently in the Annals of Internal Medicine. The study, as summarized by MinnPost.com, showed that “Inappropriate use of cardiac stress testing – particularly testing done with imaging – is costing the U.S. health care system more than half a billion dollars,…”

But in addition to the cost, cardiac stress tests with imaging subject people to radiation, which the study says each year might lead to as many as 500 future cases of cancer. So the overuse of this technology isn’t just a waste of money, it’s a threat to patient safety.

The overuse of imaging tests, as readers of this blog are aware, often figure into discussion about rising health-care costs, and some of their providers are starting to get religion. As MinnPost noted, professional medical associations have issued new practice guidelines limiting their use, and the Choosing Wisely campaign says flat out that people with a low risk of heart disease probably shouldn’t have these tests, even if they have symptoms. That’s also true for people who have been diagnosed with heart disease but who have no symptoms.

The cardiac stress test involves the patient using a treadmill or stationary bike while being hooked up to devices that measure heart rate and blood pressure. Generally, the speed, elevation and/or resistance of the exercise machine are increased, requiring greater exertion.

When imaging is included, a radioactive substance is injected into the patient’s bloodstream at rest, then again during the exercise. The illuminated substance is tracked to the heart via a special scanner similar to an X-ray machine. It’s known as a nuclear stress test.

The researchers in the new study wanted to find out why the use of cardiac stress testing was on the rise in the U.S.: The number of cardiac stress tests performed every year has more than doubled in the last two decades, from 1.6 million per year in 1993-1995 to 3.8 million per year in 2008-2010.

That means, according to MinnPost, in 1993, 28 in every 10,000 patients visiting their doctor underwent a stress test. In 2010, it was 45 in 10,000.

Some of the inflated numbers, researchers said, reflect an aging population, a demographic at higher risk for heart disease. But that can’t explain why imaging as part of a standard stress test has grown so much. Not only is that component much more expensive, but, said MinnPost, “studies have found [they] don’t add much, if any, extra clinical value. The current study found that the proportion of cardiac stress tests done with imaging – primarily nuclear stress tests – has exploded, from 49 percent in 1993-1995 to 87 percent in 2008-2010.”

At least 1 in 3 of those imaging tests probably was inappropriate, the researchers concluded. They cost $494 million annually and exposed people to radiation that could lead 491 of them to develop cancer later in life.

The same number of stress tests that don’t include imaging would cost about $7.7 million a year.

Like so much else in the medical-industrial complex, the profit motive is a big factor here, the lead researcher suggested. When a facility has fancy, expensive equipment, it wants – and needs – to use it. “Nuclear imaging stress tests command higher reimbursement,” Dr. Joseph Ladapo of New York University’s Langone Medical Center told one reporter. “No one likes to talk about this but there is plenty of evidence that physicians respond to financial incentives.”

And, Ladapo noted, there’s a widespread belief that “more intensive technology equals better care, something that we are increasingly finding to not be true. And the behaviors or practices are passed down to trainees in residency programs, so it’s a hard cycle to break.”

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