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Diagnostic imaging

Physicians ordering unnecessary DI tests, study says

TORONTO – Doctors often seem to prescribe CT and MRI scans when they are of little or no medical use, according to a story in the National Post newspaper. The phenomenon perhaps explains why Canadians still experience substantial delays to get the tests.

Large percentages of the scans reviewed by the researchers either unearthed no medical problems, or detected abnormalities that would not change how the patient was treated, raising questions about whether they should have been ordered in the first place.

According to the study authors, physicians need more education about use of the medical imaging tools, along with access to a new generation of computer programs that can advise them which test, if any, is the best for given patients.

“We need to bring things into better balance,” said Dr. John You, the internal-medicine specialist who led the research for the Institute for Clinical Evaluative Sciences.

“There are people out there for whom CTs and MRIs are probably crucial for their care and they’re probably waiting too long. There’s other people who are getting the scans and probably didn’t need to.”

But Dr. David Vickar, president of the Canadian Association of Radiologists (CAR), said that the results should be viewed cautiously. Because most CT scans for headache sufferers found nothing, for instance, does not mean that most of them should not have been done, he said.

Still, he acknowledged that as many as 20 percent of scans are ordered needlessly. “We could be doing a better job of requesting appropriate exams,” said Dr. Vickar.

The numbers of both CT scans and magnetic resonance imaging (MRI) tests performed in Canada has soared in recent years. In Ontario, for instance, the number of CT scans jumped three fold and the number of MRIs six fold between 1993 and 2003.

But wait times for the tests, considered an invaluable tool for diagnosing certain diseases and injuries, have not come down appreciably, said Dr. You. An Ontario Health Ministry official said yesterday that queues did decrease in the last year – by 16% for MRIs and 42% for CT scans.

The Fraser Institute, a conservative think tank, offers a less rosy view in its annual survey of physicians on healthcare delays, recording barely any change in wait times for the tests in Ontario last year.

Dr. You’s study scrutinized more than 22,000 outpatient CT and MRI scans carried out at Ontario hospitals on or after Jan. 1, 2005. Most strikingly, it found that headaches were the most common reason why doctors ordered CT scans of the brain, yet less than 2% of the tests revealed any treatable illness.

MRI scans of the spine were most often prescribed because the patient complained of back pain. While 90% found some kind of abnormality, it usually had nothing to do with the pain, or would not lead to any different treatment, said Dr. You.

One consequence of doing such tests is that they can lead to a “cascade” of other diagnostic procedures, he said. The result of one in four abdominal CT scans reviewed by the study, for instance, was a recommendation for more testing.

Both Dr. You and Dr. Vickar recommended wider use of computer programs that, using CAR guidelines, allow doctors to input their patient’s symptoms, and get back advice on which diagnostic test to order.

The Winnipeg children’s hospital is about to publish results from a pilot project it conducted with such software.