A Stanford study published late last month found that if your doctor buys a magnetic resonance imaging (MRI) machine, you’re more likely to get an MRI scan for lower back pain. If you go to an orthopedic surgeon, you’re also more likely to get surgery. These procedures are often not helpful to patients and can drive up healthcare costs.

“One of the major reasons why healthcare expenditures are rising is because we’re using technology such as advanced imaging such as MRIs too much,” said Jacqueline Shreibati M.S. ’09 M.D. ’10, a resident in internal medicine at Stanford and the chief investigator on the study. “We wanted to demonstrate that there is not only increased use of MRIs, but also that this increased use of MRI could lead to something called a treatment cascade, where patients can receive subsequent procedures which are of low value to the patient and that can also drive up healthcare expenditures.”

Shreibati looked at Medicare data for patients with non-specific back pain — that is, back pain without a specified diagnosis like a herniated disk or spinal stenosis. Surgery does not generally benefit this type of back pain and, in best practice, should not be prescribed.

She looked at patients seen by both primary care physicians and orthopedic surgeons for the problem. Both types of practitioners recommended more MRIs for the back pain after acquiring their own MRI machine than they did before.

Shreibati calls that problem “physician self-referral.” Since the doctor can bill for the procedure he’s recommending, he has the incentive to prescribe it, even when it’s unnecessary.

Study co-author Laurence Baker, who is also a professor of health research and policy, said there is the additional problem of efficiency and scale when private or clinic physicians buy these machines, since there is a smaller population that uses them than in a large hospital setting. He thinks the method of paying doctors leads to this wasteful situation.

“I think the payment system that we have should be reformed so that we don’t encourage a lot of purchase of this equipment in physician offices,” he said. “We should keep them in places where there is a larger population of patients and where physicians themselves don’t develop a direct financial benefit from ordering these services.”

Shreibati then addressed the question of how increased imaging affects the surgeries of patients with lower back pain. Using a two-step mathematical model, she determined that more frequent imaging after acquiring the MRI machine increased surgeries among patients of orthopedic surgeons by almost a third. For primary care doctors, there was no statistically significant relationship.

“We found a pretty tight relationship between an orthopedic surgeon ordering a scan and that scan leading to surgery,” Shreibati said.

She credited this relationship in part to a second level of self-referral, since the orthopedic surgeon will also do the surgery, and there is no additional physician involved.

This study adds to the literature on the current issue of cutting rising healthcare costs in the United States. Advanced technology adds significantly to treatment costs. Thus, cutting unnecessary use or reducing collateral spending could make a big difference.

“It goes to the bigger question of how efficient we can be with our technology,” Baker said. “How do evolving technologies impact not just the use of a particular type of service but overall care of patients?”

Shreibati hopes that the study reaches those who can change the payment system for advanced imaging in hopes of discouraging overuse.

“[The study] was aimed at a policy audience to demonstrate that there should be some caution when there is unrestrained use of MRIs, because it not only drives up healthcare expenditures in and of itself, but it can lead to increased downstream healthcare expenditures,” she said. “It’s reinforcing the importance of finding ways to restrict the use of advanced imaging.”

Medicare has already reduced the payment for MRI scans. In the face of rising costs, Baker thinks that private companies may do so as well. Both Shreibati and Baker hope that changed economic incentives for owning advanced imaging technology as a physician will play some part in the nationwide effort to reduce healthcare spending.