Self-Referred Knee MRIs Done More Often Than Needed

Self-referred knee MR imaging results are negative more frequently than examinations ordered by physicians that take place in facilities where they have no financial stake, according to a study published online in the journal Radiology.

There has been a steady increase over the past few years in the number of physicians who refer patients for imaging to a facility where the physicians or their partners have a financial interest. While there was an increase of 12 percent for non-self-referred MRI services between 2004 and 2010, there was an 80-percent increase in self-referred services.

“Our study was the first to examine one of the most common advanced outpatient imaging studies ordered in the United States today: orthopedic knee MRI,” Matthew P. Lungren, MD, said in a release. “In our work, we were able to not only evaluate the outcome of the knee MRI examinations ordered by physicians with a financial interest in the imaging equipment, but to compare this to another matched referral physician group that had no financial stake in the imaging equipment.”

Lungren is co-director or the Interventional Radiology Translational Research Lab at Duke University Medical Center in Durham, N.C.

The researchers reviewed 700 consecutive diagnostic knee exams from 667 patients, comparing whether the ordering physician was self-referring or referring to an unrelated facility. There were 350 patients in each group. The researchers analyzed the percentage of negative exams and the frequency of each type of abnormalities that were present in positive exams.

The findings showed that there were no significant differences between the two groups regarding the number of abnormalities in the positive exams, however, there were significantly more negative exams among the self-referred group. These were 33 percent more likely to be negative than the outside facility group. One-hundred-seventeen of the 205 negative exams were from the self-referred group. Only 88 negative exams were from the outside facility group.

According to the authors, the pathology, demographics, and referring physician characteristics were similar in both groups; the only difference was the physicians’ relationship with the imaging facility.

“These findings suggest that there is a different threshold for ordering MRI examinations, which may be due to financial incentive,” Lungren said.