In fact, only about 44 per cent of MRIs ordered for the lumbar spine were appropriate, the study found. The rest were deemed to be either inappropriate or of questionable value. Lead author Dr. Derek Emery said "inappropriate" in this case means unlikely to benefit the patient.
Emery said the study, which was published Monday in the journal JAMA Internal Medicine, was undertaken because there is a suspicion in medical circles that a lot of ordered MRIs are actually a waste of the resource and of the patient's time.
"There's a lot of talk out there and it's even mentioned in the literature that a lot of imaging is used inappropriately. Or a lot of imaging is unnecessary. But this has really not been rigorously studied," said Emery, a neuroradiologist in the faculty of medicine and dentistry at the University of Alberta.
Cutting back on unnecessary MRIs would help pare long waiting lists for access to the costly machines.
"MRI's a limited resource in most of Canada. Certainly it is in Alberta. And if we can eliminate some of the unnecessary scans, that will give us capacity to scan more patients who really need it," Emery said.
The study was done by researchers from the University of Alberta, the University of Calgary, the University of Toronto, and the Ottawa Hospital Research Institute.
They looked at MRI orders for two conditions — lower back pain and recurrent headaches — from the University of Alberta Hospital and the Ottawa Hospital. A panel of experts studied requisitions as they came in, assessing the appropriateness of 500 from each institution for each procedure. They used an existing nine-point scale for measuring appropriateness.
They also looked at who was doing the ordering, assessing how well different medical specialties were doing when it came to requisitioning appropriate MRIs. The acronym stands for magnetic resonance imaging, a type of scan that is particularly useful for soft tissue imaging.
Family physicians had the lowest rate of appropriate MRI orders for lower back pain, with only about one-third of the scans they requisitioned qualifying as appropriate. Neurologists and orthopedic surgeons were better, but were still under 50 per cent.
MRIs for the lumbar spine ordered by neurosurgeons were appropriate three-quarters of the time. But Emery noted neurosurgeons generally order MRIs for problems after surgery, when it's clear there may be an issue. They are not doing the basic sifting of lower back pain cases that other types of doctors are doing.
When the group studied the use of MRIs for recurrent headaches, they found a different story. Just over 80 per cent of ordered MRIs were deemed to be appropriate. That may be because most of the people who had MRIs for headaches were essentially pre-screened, having already undergone a CT scan, Emery said.
The research was funded by the Canadian Institutes of Health Research.
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