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Canadian researchers set the standard for identifying dangerous blood clots

OTTAWA, September 25, 2003 - A team of Canadian researchers is streamlining the way that patients with potentially life-threatening blood clots are cared for. As a result of their study, patients with deep vein thrombosis (DVT) should be easier to identify, they should have a faster diagnosis, and consequently there should be significant savings to the healthcare system.

Led by Dr. Phil Wells, a Senior Scientist at the Ottawa Hospital Research Institute, the group's study results are published in today's edition (September 25) of the New England Journal of Medicine.

DVT is a significant and often severe blood clot in the deep veins of the leg. It affects the equivalent of 30,000 to 60,000 Canadians per year. While DVT may not be well known outside the medical community, it is a common condition which has serious economic and social implications. First, about half of the DVT cases result in pulmonary embolism (PE), where the blood clot moves to the lungs. If left untreated, PE can result in death of about one in three of its victims. Secondly, with conservative estimates of $2,500 per case, the economic impact of DVT is about $75 million per year in Canada in associated medical costs and lost productivity.

Typically, physicians rely on a number of tools to accurately diagnose DVT, such as a clinical model to gage the patient's probability, a blood test called D-dimer, and a follow-up ultrasound. Dr. Wells' team suspected they could rule out the automatic need for ultrasound by simply using the D-dimer test in conjunction with the clinical model, that incidentally, was devised by previous research from this group, and which is being used around the world.

"Our study has shown that we can safely rule-out the need for ultrasound in patients who are deemed 'unlikely' to have a DVT using our equation, and who have a negative D-dimer result," said Dr. Wells, who is a physician at The Ottawa Hospital and an Associate Professor at the University of Ottawa's Faculty of Medicine. "This should eliminate many unnecessary ultrasounds that are currently performed 'just in case', to rule out the condition. As a result, this will save time for our patients and save dollars for our healthcare system." Dr. Wells is equally enthusiastic about how this study has reinforced the validity of the group's previous research. "In addition, we have proven that our Canadian (Ottawa) homegrown model of care for identifying DVT patients is truly effective, and worthy of use around the world," he said.

This clinical randomized trial lasted two years, and had the participation of over 1,000 patients in centres in Halifax, Hamilton, London and Ottawa.

Dr. Wells and his research team's work would not be possible without the generous support of the Heart and Stroke Foundation and the Canada Research Chair Program.

About the Ottawa Hospital Research Institute (OHRI):
The OHRI is an institute of The Ottawa Hospital and the University of Ottawa. With more than 200 scientists, 225 students and more than 400 support staff, and $42 million in external funding, the OHRI is one of the fastest growing and most respected hospital-based research institutes in Canada. For more information on the OHRI, visit our web site at:


Media Contact:
Ron Vezina, Manager, Public Affairs and Media Relations, The Ottawa Hospital, (613) 737-8460.

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