Self-Referring Physicians Have Lower Threshold for Knee MRI

Marcia Frellick

September 17, 2013

When physicians have a financial interest in imaging equipment, they are much more likely to order knee magnetic resonance imaging (MRI), according to a study published online September 17 in Radiology.

The practice is called self-referral, meaning physicians who are not radiologists refer patients to imaging facilities in which they or their partners have a financial interest.

In the current study, Matthew Lungren, MD, codirector of the Interventional Radiology Translational Research Lab at Duke University Medical Center in Durham, North Carolina, and colleagues reviewed 700 diagnostic knee exams from 667 consecutive patients at a single radiology clinic. The researchers divided the patients into 2 groups: 1 with patients referred by physicians with a financial interest in the imaging equipment used and 1 in which patients were referred by physicians with no financial interest in the equipment.

For each group, the team assessed the percentage of negative exams and the frequency of abnormalities found on positive exams.

Overall, 205 MRIs were negative: 117 ordered by physicians with a financial interest and 88 ordered by physicians without a financial stake (P =.016). In other words, knee MRIs ordered by physicians who had a financial interest were 33.4% more likely to be negative than those ordered by physicians with no such financial interest, which indicates a significantly higher number of potentially unnecessary scans. There was no significant difference in the number of abnormalities per positive scan between the groups.

"This occurred despite otherwise highly similar pathology, demographics and referring physician characteristics between the two groups," Dr. Lungren and colleagues write. "These findings suggest that there is a different threshold for ordering MRI examinations which may be due to financial incentive."

Self-referral percentages are growing disproportionately. According to the Government Accountability Office, from 2004 through 2010, the number of self-referred MRI services increased by more than 80%, whereas non-self-referred MRI services increased only 12%.

Self-referrals also add financial strain to the health system. The Government Accountability Office estimates that in 2010, providers who self-referred made up to 400,000 more referrals for advanced imaging than they would have if they were not self-referring, costing Medicare about $109 million.

"Our findings suggest the likelihood of overutilization of knee MR imaging among physicians who own MR imaging equipment and support including financial interest in imaging equipment in the consideration for cost-containment efforts by government and third-party payers," the authors conclude.

The authors have disclosed no relevant financial relationships.

Radiology. Published online September 17, 2013.


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