RSNA: Self-referral ups negative, possibly unnecessary, MRI exams

Colored areas represent brain locations where more heading was associated with diffusion tensor imaging abnormalities similar to those seen in traumatic brain injury affecting the white matter. Source: RSNA

CHICAGO--Physicians who have a financial interest in imaging equipment are more likely to refer their patients for potentially unnecessary imaging exams, according to a study presented Nov. 30 at the annual meeting of the Radiological Society of North America (RSNA).

"Self-referred medical imaging has been shown to be an important contributor to escalating medical costs," said Ben E. Paxton, MD, radiology resident at Duke University Medical Center in Durham, N.C.

Between 2000 and 2005, ownership or leasing of MRI equipment by non-radiologists grew by 254 percent, compared to 83 percent among radiologists. The U.S. Government Accountability Office (GAO) reported that the proportion of non-radiologists billing for in-office imaging more than doubled from 2000 to 2006. During that same time period, private office imaging utilization rates by non-radiologists who control patient referral grew by 71 percent.

For the study, the researchers set out to determine if utilization of lumbar spine MRI differs, depending on the financial interest of the physician ordering the exam. They reviewed 500 consecutive diagnostic lumbar spine MRI exams ordered by two orthopedic physician groups serving the same community. The first group had financial interest in the MRI equipment used (FI group), and the second had no financial interest in the equipment (NFI group).

For each group, the researchers analyzed the number of abnormalities per positive scan, the mean age of the patients and the negative exam result rate.

The results of the study showed that among the 500 MRI exams (250 per group), between the two groups there was no significant difference in the number of abnormalities per positive scan. However, the mean age among patients in the FI group was 49.6 years, compared to 56.9 years for the NFI group.

There were 86 percent more negative scans in the FI group than the NFI group, indicating a significantly higher number of potentially unnecessary exams. Of the 163 negative exams, 106 belonged to the FI group, compared to 57 for the NFI group. In the FI group, 42 percent of patients referred for exams had negative scans, compared to 23 percent of the NFI group.

"Orthopedic surgeons with financial interest in the equipment had a much higher rate of negative lumbar spine MRIs," Paxton said. "In addition, they were much more likely to order MRI exams on younger patients. This suggests that there is a different clinical threshold for ordering MRI exams in the setting of financial incentivization."

Paxton added that increased imaging utilization due to self-referral may not yield medically useful information and may place the patient at risk for potential adverse consequences.