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Ottawa Decision Tool Detects 100% of Subarachnoid Hemorrhage (SAH) Cases, Could Save Province $25 Million

With headache as its predominant symptom, subarachnoid hemorrhage (SAH) can be dangerously challenging to diagnose, with a 50% fatality rate for misdiagnosis. A clinical decision tool developed at The Ottawa Hospital decreases that number to 0% by detecting 100% of SAH cases.

Emergency doctors at The Ottawa Hospital are now using a simple clinical decision tool that can identify which patients with headache are in fact experiencing a dangerous subarachnoid hemorrhage or SAH (bleeding in a certain area of the brain).

An estimated 49 patients presenting with SAH in Ontario annually are misdiagnosed at the time of their first visit. It is estimated that half of those patients die as a result of misdiagnosis, with many survivors affected by neurological damage. Recognizing the need for a better solution, Dr. Jeffery Perry, Senior Scientist and Emergency Physician at The Ottawa Hospital, together with his research team developed the Ottawa SAH Rule, which virtually solves the difficult challenge of diagnosing SAH.

Studies have proven that this clinical decision tool allows doctors to correctly identify 100% of SAH cases, accelerating the urgent treatment needed by patients. As a result, the Ottawa SAH Rule introduces potential cost savings of $25 million through avoiding death and disability.

Dr. Jeffery Perry, Senior Scientist at The Ottawa Hospital
Dr. Jeffery Perry, Senior Scientist at The Ottawa Hospital

Reducing Misdiagnosis to Zero

“Unfortunately, subarachnoid hemorrhage can be difficult to diagnose because the main symptom for many patients is a headache,” said Dr. Perry, who is also a Professor at the University of Ottawa.

Headache is a common symptom, often resulting from a myriad of conditions, from fatigue to dehydration. When patients visit the emergency department with headache as their only symptom, it can be a challenge to determine whether investigations are required.

“Our rule can help doctors determine which headache patients should be given further tests for subarachnoid hemorrhage, and our studies show that applying this rule would reduce the rate of initial misdiagnosis to close to zero,” continued Dr. Perry. “If we can reduce misdiagnosis, we should be able to speed up treatment and save hundreds of lives every year.”

A Simple Rule that Saves Lives

With funding from Canadian Institutes of Health Research (CIHR), Dr. Perry and his team were able to test the Ottawa SAH Rule.

The study involved 2,131 adult patients who visited 10 Canadian emergency departments between April 2006 to July 2010, with a headache peaking within one hour and no neurologic deficits. The researchers evaluated previously developed clinical decision rules, refining the Ottawa SAH Rule to employ three key steps:

The Ottawa SAH Rule

  1. For alert patients older than 15 years with new severe non-traumatic headache reaching maximum intensity within 1 hour.
  2. Not for patients with new neurologic deficits, previous aneurysms, SAH, brain tumours, or history of recurrent headaches (≥ 6 months).
  3. Investigate if ≥ 1 high risk variables present:
    • Age ≥ 40 years
    • Neck pain or stiffness
    • Witnessed loss of consciousness
    • Onset during exertion
    • Thunderclap headache (instant peaking pain)
    • Limited neck flexion on examination

Employing the Ottawa SAH Rule, emergency room doctors accurately diagnosed 132 patients (6.2 per cent) with SAH, with zero missed cases.

A brain aneurysm can turn into a deadly subarachnoid hemorrhage if it bursts. A brain aneurysm can turn into a deadly subarachnoid hemorrhage if it bursts.
A brain aneurysm can turn into a deadly subarachnoid hemorrhage if it bursts.

Saving Ontario $25 Million

Dr. Perry’s Ottawa SAH Rule is an Ontario game-changer for patients and the economy. A Centre for excellence in Economic Analysis Research study has shown that its ability to significantly improve patient outcomes saves the province substantial dollars by keeping Ontarians healthy and working.

An estimated 49 patients are misdiagnosed annually without the use of the Ottawa SAH Rule, resulting in death for 50% of patients, and disability for 20%. By removing or limiting participation in the Ontario workforce, the economy saw significant loss:

  • Earnings lost due to death from misdiagnosis exceeded $18.6 million
  • Earnings lost due to disability from misdiagnosis exceeded $6.76 million
  • Total lost earnings over a one-year period without use of the SAH rule exceeded $25.4 million

By correctly diagnosing 100% of SAH cases, the Ottawa SAH Rule could potentially save Ontario over $25 million annually.

The development and implementation of this rule underscores the fact that the impact of health research extends beyond patient care by introducing cost savings for the provincial economy. By generating smarter methods for treatment, health research contributes to a healthier, wealthier Ontario.

The SAH study led by Dr. Jeffery Perry is published in the September 25 issue of the Journal of the American Medical Association (JAMA).