Go to content

Stroke survival better at hospitals with higher volumes of ischemic stroke care: Ontario study


Patients admitted to hospitals with low volumes of ischemic stroke care are more likely to die within 30 days than patients admitted to hospitals that see high volumes of ischemic stroke care, says a new study from the Institute for Clinical Evaluative Sciences (ICES) and the Ontario Stroke Network (OSN).

An ischemic stroke is a sudden loss of brain function caused by the interruption of blood flow to the brain due to a clot or other obstruction. The longer brain tissue goes without oxygen and nutrients, the greater the risk of permanent damage. Ontario established a regionalized stroke system in 2001, with full implementation in 2005. There are currently 28 Ontario hospitals designated as stroke centres, each with protocols and the capacity for appropriate diagnostic tests, clinical expertise and follow-up care.

Published today in the journal Circulation: Cardiovascular Quality and Outcomes, this study is the largest to date to examine the links between stroke care volume and mortality. The researchers reviewed all 73,000 adult ischemic stroke cases at 162 Ontario hospitals in a seven year period between 2005 and 2012. Excluding strokes that happened in hospital, as well as elective admissions, they followed the anonymized patient charts to identify deaths that occurred at seven and 30 days following the initial stroke event. Adjusting for various patient risk factors, they compared the likelihood of mortality for each hospital.

“We found that stroke patients treated at smaller volume hospitals had a 47 per cent higher risk of dying in the first week compared to patients admitted to larger volume hospitals, and a 37 per cent higher risk of dying after 30 days,” says the study’s lead author Ruth Hall, an adjunct scientist at ICES and evaluation lead for the Ontario Stroke Network. “However, we found no statistically significant difference in rates of death after stroke between medium and high volume hospitals.”

Among the study’s findings:

  • Annually overall, there were 800 deaths within seven days of hospital treatment for ischemic stroke and 1,600 deaths within 30 days (a mortality of 7.6 per cent and 15.3 per cent, respectively).
  • Lower stroke volume hospitals in Ontario saw an average of 29 stroke patients per year; medium volume hospitals saw an average of 156 cases per year; and higher stroke volume hospitals admitted an average of 290 stroke patients yearly.
  • Using adjusted modelling, the researchers determined that 875 deaths could potentially be avoided if patients seen at small volume hospitals were referred to hospitals that admitted at least 126 ischemic stroke patients annually.
  • All hospitals with 165 or more ischemic stroke admissions per year had mortality rates that were  at or below the provincial rate, suggesting a possible threshold for admissions.

“Our study strongly supports the recommendations of the Quality Based Procedures Clinical Handbook for Stroke produced by Health Quality Ontario, the Ministry of Health and Long-Term Care and the Ontario Stroke Network,” says Dr. Mark Bayley, senior author on the paper who is also an adjunct scientist at ICES, and Chair of the OSN Stroke Evaluation and Quality Committee. “These findings demonstrate that by consolidating acute stroke care in each region in Ontario, we can ensure that every person experiencing stroke will receive the best possible care.”

“Does the volume of ischemic stroke admissions relate to clinical outcomes in the Ontario stroke system?” was published today in the journal Circulation: Cardiovascular Quality and Outcomes.

Author block: Ruth E. Hall, Jiming Fang, Kathryn Hodwitz, Gustavo Saposnik, Mark T. Bayley.

The Institute for Clinical Evaluative Sciences (ICES) is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of healthcare issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting healthcare needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy. For the latest ICES news, follow us on Twitter: @ICESOntario

The Ontario Stroke Network provides provincial leadership and planning for the continuum of stroke care in Ontario—from health promotion and stroke prevention to acute care, recovery, rehabilitation and reintegration. Visit the OSN’s website at http://www.ontariostrokenetwork.ca.


  • Kathleen Sandusky
  • Media Advisor, ICES
  • [email protected]
  • (o) 416-480-4780 or (c) 416-434-7763


Contributing ICES Scientists

Research Programs

Associated Sites

Read the Journal Article