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Canadian rules for reducing unnecessary CT scanning proven 100 percent accurate

Ottawa, September 27, 2005

A new study has paved the way for worldwide adoption of the Canadian CT Head Rules, a list of seven simple criteria meant to help emergency room physicians decide if a patient with a concussion requires an expensive CT scan. The study, to be published tomorrow in the Journal of the American Medical Association, shows that these rules can identify 100 percent of serious head injuries by scanning just 52 percent of patients with concussions. Adopting these rules would dramatically cut the need for CT scanning, which would save money, reduce emergency department overcrowding, reduce wait times, and reduce patient radiation exposure.

Dr. Ian Stiell, Head of the Department of Emergency Medicine at the University of Ottawa led the study. Dr. Stiell is also a Senior Scientist and Chair of Emergency Medicine Research at the Ottawa Hospital Research Institute (OHRI), and a physician in the Department of Emergency Medicine at The Ottawa Hospital.

"In 2001, we used patient records to develop the Canadian CT Head Rules and we predicted that these rules could cut CT scanning for minor head injuries almost in half," said Dr. Stiell. "But this is the first time we have actually tested the rules in a real setting with hundreds of emergency room physicians. We found that the rules were just as accurate, efficient and user-friendly as we had predicted. The challenge now is to get doctors in Canada and around the world to start using the Canadian CT Head Rules on a day-to-day basis."

Nine large Canadian hospitals and 2707 patients participated in the study. This research is also the first to directly compare the Canadian CT Head Rules with the New Orleans Criteria, a similar set of rules which are widely disseminated in the US. While both rules were proven 100 percent accurate, the New Orleans Criteria required scanning far more patients (88 percent versus 52 percent).

Each year, physicians in Canadian and US emergency departments treat more than eight million patients with head injuries. The vast majority of these injuries are minor concussions that require no follow-up care, but about one in every 200 patients will have a life-threatening blood clot in the brain that may require surgery. Use of CT scans, which can detect these clots, has increased dramatically in the last decade. Eighty percent of Canadian patients with concussions were given a CT scan in 2002, compared with just 30% in 1997. In US emergency departments, CT scanning for all conditions has more than doubled, from 2.4 percent in 1992 to 5.3 percent in 2000.

A CT scan in the US costs between $500 and $800, and it has been estimated that even a ten percent reduction in use could save $20 million a year (all $US). In Canada, the dollar values are more difficult to calculate, but it is known that patients who underwent CT scans spent an average of 2.5 hours longer in the emergency department than patients who did not.

Dr. Stiell's group has developed several other clinical decision rules, including the Ottawa Ankle Rules for X-rays, which were featured on an episode of the television show ER.

The Canadian CT Head Rules state that a CT scan is required for any patient with a minor head injury and any one of the following seven characteristics:

1. Reduced mental, verbal, or eye response two or more hours after the injury (Glasgow Coma Scale 13-15).
2. Suspected open or depressed skull fracture.
3. Any sign of basal skull fracture (for example, raccoon eyes).
4. Two or more episodes of vomiting.
5. 65 years or older.
6. Amnesia before impact of 30 or more minutes.
7. Dangerous mechanism (for example, flying through a car windshield).

The study was published in the September 28 issue of the Journal of the American Medical Association ( Funding for the study was provided by the Canadian Institutes of Health Research (CIHR), and the Ontario Ministry of Health, Emergency Services Committee.
Media Contact: Jennifer Paterson Communications Manager, Ottawa Hospital Research Institute 613-798-5555 extension 19691

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