Physicians were more likely to order potentially unnecessary knee imaging when they had a financial stake in it, a study showed.
MRI scans turned up negative in significantly more patients referred by physicians with an ownership interest in the imaging equipment than by those without any financial incentive (33% versus 25%, P=0.016), Matthew P. Lungren, MD, of Duke University Medical Center, and colleagues found.
Other patient and physician characteristics appeared largely similar between groups, leaving no other apparent good reason for the self-referral difference, the researchers reported online in Radiology.
"Our findings suggest that there may be a lower threshold for referral to MR imaging of the knee in the financially incentivized ordering group," they concluded.
The study couldn't prove intentional overuse due to a profit motive, but that possibility might be worth consideration by government and third-party payers, the group suggested.
"Despite the limitations, we believe that the inherent conflict of interest present when physicians both order and then perform and collect fees on the basis of the acquisition of MR imaging examinations is an important factor to consider whenever the matter of health care cost is raised," they wrote.
Diagnostic imaging's contribution to the growth in healthcare spending has been leveling off overall, but "self-referral in advanced diagnostic imaging continues to increase among nonradiologist physicians and has been shown to be a major contributor to higher utilization and costs of imaging," the group pointed out.