A study just published in the September edition of the American Journal of Roentgenology (AJR) looked at 1140 consecutive shoulder MRIs and found patients of physicians who own MRI equipment are 25.6% more likely to have negative scans than physicians who do not own MRI machines. The authors conclude “there may be a lower threshold for shoulder MRI referral in the financially incentivized group.”
There were only two groups in this retrospective study: a group composed of orthopedic surgeons who own MRI machines and a group of orthopedic surgeons who do not. All of the MRIs were read by a single group of radiologists at an academic medical center who had no financial interest in the technical component of the scans (obviously they had a financial interest in the professional component, though).
The authors compiled a list of twenty different lesions that were considered a “positive” study. The injuries on the list are “common causes of shoulder pain and are clinically important indications for more invasive interventions, such as surgery, for which imaging is commonly performed.”
Five hundred and seventy consecutive scans from the self-referral group and 570 consecutive scans from the non-self-referral group were reviewed. The authors found there was no statistically significant difference between the two groups with respect to patient age or the total average number of lesions per scan. But there was a significantly higher number of negative scans (25.6% higher) in the self-referral group compared to the non-self-referral group.
The authors state this study:
used a unique approach to address the utilization patterns of referring clinicians with financial interest in medical imaging equipment—namely, rather than auditing financial and billing data, final imaging diagnoses on imaging studies were analyzed to control for severity of disease between referring physician groups (financially incentivized vs non–financially incentivized).
I’m not sure this is true. Last June I wrote about another paper in AJR that compared negative spinal MRI rates between self-referring and non-self-referring orthopods and found the self-referral group had 86% more negative spine MRIs.
And with the exception of the first author on both studies, all of the authors on the two studies are the same.
The authors also say their study, in isolation, “does not prove intended overutilization for profit.” They are correct in that.
But it is yet another addition to the ever-growing body of literature evidence that financial incentives significantly alter physician behavior.
The link to the abstract is here.