03/25/2013 18:27 EDT | Updated 05/25/2013 05:12 EDT

Many MRIs for lower back pain unnecessary

More than half of MRIs of the lower back that were ordered at two Canadian hospitals were either inappropriate or of questionable value for patients, researchers say.

Use of MRI to image the lumbar spine has increased in Canada and the United States despite a lack of a clear correlation between imaging findings and clinical signs and symptoms, Dr. Derek Emery wrote in Monday's online issue of the journal JAMA Internal Medicine.

"Our study has implications for management of MRI usage for the lumbar spine, which makes up approximately a third of all MRI in some regions," Emery, of the radiology and diagnostic imaging department at the University of Alberta, and his co-authors said.

"Eliminating inappropriate scans and some of uncertain value could reduce the harm that accrues from unneeded investigations and result in significant cost savings."

Of the requests from family doctors, about 34 per cent were considered appropriate versus 58 per cent for other specialists.

Emery's team had a panel of specialists rate clinical requests for outpatient MRI for lumbar spine and headache on a nine-point scale for appropriateness.

Of the 1,000 requests for lumbar spine MRI, 443 were considered appropriate, the researchers said. The rest were split between inappropriate (28.5 per cent) or uncertain value (27.2 per cent).

The only indication that was nearly uniformly considered appropriate was MRI for postoperative leg or back pain, which accounted for less than 17 per cent of all MRI lower back scans.

Most MRI requests for headache, 82.8 per cent, were considered appropriate. Most patients referred for MRI of the head for headache had been screened with a CT scan, which the researchers said likely explained the high appropriateness rating.

The researchers called on medical societies to show leadership in reducing overuse, which they said was driven by patient expectations, physician concerns about litigation and lack of physician accountability for cost.

Since the study, funded by the Canadian Institutes of Health Research, only looked at the University of Alberta Hospital and Ottawa Hospital, the findings may not apply in other health systems.