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Cardiac stress tests done with imaging have risen substantially and more than a third appeared inappropriate, according to a national study.

While the annual frequency of cardiac stress testing stayed constant after adjustment for other factors, the proportion done with imaging rose from 59% in 1993-1995 to 87% in 2008-2010, , of NYU Langone Medical Center in New York City, and colleagues found.

", with associated annual costs and harms of $501 million and 491 future cases of cancer," they reported in the Oct. 7 issue of the Annals of Internal Medicine.

Financial incentives may be one reason, Ladapo told 番茄社区.

"Nuclear imaging stress tests command higher reimbursement," he said. "No one likes to talk about this but there is plenty of evidence that physicians respond to financial incentives."

In the study of National Ambulatory Medical Care Survey and National Hospital Ambulatory Medical Care Survey data from 1993-2010, there was some support for this explanation.

For example, "among the factors that contributed to the increasing overall trends, many were patient or clinical characteristics associated with an increased risk for coronary heart disease, but the independent contributions of private insurance and Medicare suggest that trends are at least partially driven by nonclinical, and possibly economic, motivations."

Significant independent predictors of cardiac stress testing in the databases included:

• Having private insurance (61% higher adjusted odds versus no insurance)
• Having Medicaid (41% lower adjusted odds)
• Being male (39% higher adjusted odds versus women)
• Presenting with chest pain (36-fold higher adjusted odds)
• Seeing a cardiologist (14-fold higher adjusted odds)

A bigger factor than reimbursement, though, might be "the common belief that more intensive technology equals better care, something that we are increasingly finding to not be true," Ladapo said. "And the behaviors or practices are passed down to trainees in residency programs, so it's a hard cycle to break."

"Clinically, we need effective decision support tools to help physicians more appropriately identify patients who would benefit from imaging cardiac stress tests," he suggested.

Defensive medicine is an unlikely explanation for the trends, he said, because "exercise treadmill tests without imaging work pretty well in comparison to tests with imaging. In fact, they probably are a better predictor of cardiovascular risk than the imaging portion."

The study suggested just a substitution of imaging for non-imaging tests.

The annual number of U.S. ambulatory visits with a cardiac stress test ordered or performed increased from 28 to 45 per 10,000 visits. But adjustment for patient characteristics, risk factors, and provider characteristics brought the trend down to a nonsignificant P-value of 0.134.

"In conclusion, growth in cardiac stress testing can largely be explained by changes in population demographics, risk factors, and provider characteristics, but growth in the use of imaging cannot," the researchers wrote.

They cautioned that their conservative approach to identifying inappropriate tests (patient characteristics considered "rarely" appropriate by criteria from the American Heart Association, American College of Cardiology, and others) likely underestimated their overall frequency.

The databases were also limited in the amount of clinical information on each patient visit to determine appropriateness, the group noted, which meant chest pain often couldn't be determined as typical or atypical and type of imaging used couldn't be distinguished.

From the American Heart Association:

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