Study finds back surgery, number of scanners linked

Health analysts have long complained that an abundant supply of health facilities, or particular types of physicians, increases the probability for diagnosis and treatment of conditions related to that specialty.

Now a study published in the November/December issue of Health Affairs has found the principle “to a hammer, everything looks like a nail” also applies to MR scanner supply and imaging demand. In fact, an abundant supply of MRI devices increases the likelihood low back surgery will be prescribed. The behavior of local radiologists is probably not associated with the trend.

Looking at Medicare claims data from 1998 to 2005 to assess the experience of patients with low back pain, Stanford University researchers divided geographic areas across the U.S. into four groups, from high to low, in terms of the number of outpatient MRI services that bill Medicare.

Patients in communities with the most MR scanners had a 17.2% chance of getting scanned within a given year. In low MR availability areas, patients had a 15.8% chance of getting scanned, according to coauthor Dr. Laurence Baker, a professor of health research and policy at Stanford.

The minor-seeming percentage difference amounted to 6388 more scans performed annually in areas with big scanner inventories than in those with few scanners. If all Medicare low back pain patients in 2004 lived in the lowest MRI-availability areas, 12,277 fewer lumbar MR scans would have been performed, Baker and collaborator Jacqueline D. Baras concluded.

Though the American College of Radiology Appropriateness Criteria are designed to reduce inappropriate imaging in situations such as this, as this, radiologists admitted imagers are usually in a poor position to personally intervene to halt wasteful practices.

“Radiologists don't want to alienate their referral sources,” said Dr. David Levin, a professor of radiology at Thomas Jefferson University.

Guidelines for low back pain care call for a six-week waiting period before lumbar MRI is carried out. Imaging performed during the observation period may lead to unnecessary surgeries because MR identifies abnormalities unrelated to the symptoms, Baker said.

“The challenge society faces is figuring out when to use new advanced imaging technologies so we can benefit from them without wasting resources- or even ending up worse off because of overuse,” he said.

But more factors than just inventory should be examined before changing healthcare policy, Levin said. Insurer utilization management policies may also have influenced use patterns.

“It’s possible there were low MRI (numbers) in the areas where the radiology benefit managers are strong and therefore there are fewer MRIs- because the radiology benefit managers are putting a lid on it,” he said.