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Last updated on April 20, 2014 at 8:28 EDT

Cutting Back on Unnecessary MRI and CT Scans Could Cut Wait Times: Study

June 26, 2008

By Helen Branswell, Medical Reporter, THE CANADIAN PRESS

TORONTO – Wait times for MRI and CT scans in Ontario – and probably elsewhere in Canada – could be reduced by cutting back on unnecessary scans ordered by doctors, a new study suggests.

The work, an analysis of why scans were ordered and what treatment course was followed based on the results, suggests more rational use of the machines should be considered.

“I think all of Canada is experiencing challenges with wait times. And I guess our message would be if you can cut down the inappropriate use, then you can actually improve access for the people who actually will benefit,” lead author Dr. John You said Thursday.

“Ontario has tried very hard to bring down wait times for CT-MRI. They’ve invested large sums of money and that’s clearly one part of the solution, is to improve capacity. But I guess what we’re seeing with our study is that not only do you have to look at that supply side by increasing capacity, but you’ve got to look at the demand side too.”

The study, published in the June issue of the Canadian Association of Radiologists Journal, was conducted by researchers at Toronto’s Institute for Clinical Evaluative Sciences. The work was funded by the Ontario Ministry of Health and Long-term Care’s Ontario Wait Time Strategy.

The findings are specific to Ontario, but You said he felt it’s likely the same thing is happening elsewhere across the country.

“I wouldn’t be surprised if in most jurisdictions you found that there was some suggestion of overuse or inappropriate use.”

The researchers suggested this study is the beginning of an exploration into whether CT and MRI resources in Ontario are being used rationally and responsibly. But even at this early stage there are clues that factors other than medical need may be driving the decision to order diagnostic imaging tests.

For instance, the study found MRI use is higher for patients who live in high-income neighbourhoods, even though it’s well known that people on low incomes tend to have more health problems.

Another factor may be fear of lawsuits.

U.S. doctors are known to order tests to protect themselves against litigious patients. Even though medical malpractice suits are more common south of the border, concern about being seen to have dotted all the i’s and crossed all the t’s may be playing a role here too, said You, a scientist at ICES and a general internal medicine specialist at McMaster University in Hamilton.

“Clearly in the United States it’s out of control. But I think in Canada certainly in talking to colleagues or hearing my colleagues speak, I think there’s certainly a fear of malpractice litigation. And that is one factor that may drive physicians to order tests that they think really are probably not absolutely necessary.”

Cutting wait times for imaging tests is one of the priorities set by the 2004 wait time accord between the provinces and the federal government.

In Ontario the number of CT scanners has increased four-fold and the number of MRI scanners increased 12-fold between 1993 and 2006. Currently, the estimated wait for a CT scan is 5.5 weeks and 14 weeks for an MRI scan.

For the study, You and his co-authors selected a random sample of 20 Ontario hospitals performing CT scans and 20 performing MRIs.

They looked at chart data for roughly 200 scans for each of the three anatomical regions – abdomen-pelvis, brain or chest for CT scans and brain, spine or extremities for MRIs – studying the reason given for ordering the scan, the finding and the recommended course of treatment. In total, they studied data from 11,824 CT scans and 11,867 MRIs performed after Jan. 1, 2005.

They found that while CT scans of the brain were most commonly ordered for headaches, less than two per cent of those scans revealed a treatable abnormality.

You noted that a normal scan isn’t always a waste of resources – it can help rule out conditions and provide peace of mind for patients. “But certainly if only two per cent of scans are showing something useful in terms of actionable results, then probably that’s a little bit too small. And there’s probably a better use of CT out there than for a headache.”

In MRIs of the spine, 90 per cent showed abnormal results. But it wasn’t clear how important that information is, You said. He pointed out that scans of seemingly healthy people would also turn up abnormalities that don’t cause problems and that resolve themselves without therapy.

The study also found huge variability in rates of tests done for various conditions, the most notable of which was CT scans of the abdomen for diagnosis of kidney stones. There was a 70-fold difference between the hospital which had the lowest rate of scanning for kidney stones compared to the hospital with the highest rate of such scans.

“That’s a huge difference,” You said, adding that while some variation is probably legitimate, a 70-fold difference does raise questions.

One in four CT scans of the abdomen-pelvis and of the chest resulted in a recommendation for further testing, a fact the authors said belies the commonly held notion that an imaging test will lead to a definitive diagnosis.

The authors noted that while doctors often justify ordering scans by saying patients demand them, those patients might feel differently if they realized there was a real likelihood that an answer wouldn’t be found and additional, possibly invasive tests might be ordered as a followup.

Given how much the province has invested in additional CT and MRI scanning equipment since 2005, it’s important to assess how well the machines are being used, the authors said.

They suggested the province should develop a web-based ordering system that would capture, in real time, the reasons why imaging tests are ordered and test results. Such a system would make it easier to audit the appropriateness of ordering patterns, they said.