Physician trainees across a variety of specialties exhibit “a striking knowledge gap” regarding the costs of common diagnostic imaging examinations and often vastly over-estimate these costs, according to a new survey by researchers at Emory University School of Medicine, Atlanta.

To the authors’ knowledge, “this was the first large multi-specialty assessment of imaging cost knowledge,” corresponding author Dr. Arvind Vijayasarathi told Reuters Health by email.

He and his colleagues acknowledge that it’s difficult to define “cost” in health care. Therefore, in an online survey available to all 1,238 physicians in internships, residencies, and fellowships at Emory, they asked respondents for their best estimate of Medicare national average total allowable payments (taking into account both radiologist and facility fees) for five common examinations: two-view chest radiography, contrast-enhanced CT abdomen and pelvis, unenhanced CT brain, unenhanced MRI lumbar spine, and complete abdominal ultrasound.

The Medicare national average allowable fee “reflects the actual dollar amount that changes hands for a given diagnostic imaging examination (total Medicare payments and patient co-insurance payments) in a large segment of the US population,” the authors noted in their report online July 27 in the Journal of the American College of Radiology.

Overall, 381 (30.8%) of the residents and fellows completed the survey. Only 5.7% of their 1,905 responses were “correct,” that is, within 25% of the actual fee, and 76.4% of all respondents got none of the five answers correct.

Only one trainee was able to correctly estimate the cost of more than two types of examinations, and the mean absolute percentage error across all examinations was 561%. Almost 87% of all responses were incorrect overestimates, while only 7.5% were incorrect underestimates.

It seems advisable, the researchers say, both to provide focused cost-related education in medical school and to integrate imaging cost information into clinical decision support systems and computerized physician order entry systems.

Dr. Vijayasarathi suggests that the very large preponderance of overestimates (which was consistent with an earlier study by these researchers, in a population of radiology trainees) was likely biased by other values, such as hospital charges/list prices.

Depending on the hospital, he continued, the consistent overestimates “could be closer to what patients actually see when they view their bill, or in some cases are personally billed (if they are uninsured or underinsured). It is unclear to us what effect, if any, increased knowledge of costs would have on imaging ordering patterns.”

Possibly more important than knowing an actual dollar cost of an imaging study or other diagnostic or therapeutic service, Dr. Vijayasarathi said, would be understanding relative costs. If, for example, ultrasound, MRI or a new laboratory test could answer the same clinical question, a physician should probably consider their relative costs, in addition to other factors.