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When is a headache a sign of a deadly brain bleed? Ottawa rule could improve diagnosis and save lives

November 13, 2017

More than 150,000 people visit Canadian emergency departments each year because of a headache. While it usually isn’t serious, in 1-3 percent of cases a bad headache can be a sign of dangerous bleeding in the brain, also called subarachnoid hemorrhage or SAH.

Dr. Jeffrey Perry and his colleagues developed the Ottawa SAH Rule to help emergency doctors determine which headache patients might have SAH. A new study published in CMAJ validates the rule in more than a thousand patients in six hospitals, showing that it could detect 100% of SAH cases. A previous analysis estimated this would save 25 lives each year in Ontario. The rule also allowed doctors to rule out SAH in 13% of headache patients without the need for brain imaging.

Researchers at The Ottawa Hospital and the University of Ottawa are internationally recognized for their clinical decision rules.

Authors: Jeffrey J. Perry, Marco L.A. Sivilotti, Jane Sutherland, Corinne M. Hohl, Marcel Émond, Lisa A. Calder, Christian Vaillancourt, Venkatesh Thirganasambandamoorthy, Howard Lesiuk, George A. Wells, Ian G. Stiell.

Funding: This research was possible because of generous donations to The Ottawa Hospital for Research to Improve Patient Care. The researchers have also received support from the Canadian Institutes of Health Research, the University of Ottawa, the Southeastern Ontario Academic Medicine Association and the Vancouver Coastal Health Research Institute.

The Ottawa Hospital: Inspired by research. Driven by compassion


The Ottawa Hospital is one of Canada’s largest learning and research hospitals with over 1,100 beds, approximately 12,000 staff and an annual budget of over $1.2 billion. Our focus on research and learning helps us develop new and innovative ways to treat patients and improve care. As a multi-campus hospital, affiliated with the University of Ottawa, we deliver specialized care to the Eastern Ontario region, but our techniques and research discoveries are adopted around the world. We engage the community at all levels to support our vision for better patient care. See www.ohri.ca for more information about research at The Ottawa Hospital.

University of Ottawa: —A crossroads of cultures and ideas


The University of Ottawa is home to over 50,000 students, faculty and staff, who live, work and study in both French and English. Our campus is a crossroads of cultures and ideas, where bold minds come together to inspire game-changing ideas. We are one of Canada’s top 10 research universities—our professors and researchers explore new approaches to today’s challenges. One of a handful of Canadian universities ranked among the top 200 in the world, we attract exceptional thinkers and welcome diverse perspectives from across the globe. www.uottawa.ca

Media Contact


Jennifer Ganton
Director, Communications and Public Relations
Ottawa Hospital Research Institute
Office: 613-798-5555 x 73325
Cell: 613-614-5253
jganton@ohri.ca