Predictive value of the Ontario prehospital stroke screening tool for the identification of patients with acute stroke

Prehosp Emerg Care. Apr-Jun 2009;13(2):153-9. doi: 10.1080/10903120802706146.


Background: In 2005, a prehospital stroke screening tool was implemented in Toronto, Ontario, Canada. Patients identified by paramedics through the use of this tool in the field were transported to a regional stroke center under an acute stroke protocol.

Objective: To determine the positive predictive value (PPV) of the Ontario Prehospital Stroke Screening Tool for identification of acute stroke at a single stroke center.

Methods: We conducted a retrospective analysis of consecutive patients transported to a regional stroke center under the prehospital acute stroke protocol over a 12-month period. Final diagnoses, treatments, and outcomes were abstracted from a provincial registry. Rates of fibrinolysis were compared with those for the 12-month period prior to implementation of the stroke protocol.

Results: Three hundred twenty-five patients were triaged under the emergency medical services (EMS) acute stroke protocol over the study period. The PPV of the screening tool was 89.5% (95% confidence interval [CI]: 85.7-92.7%) for acute stroke. Thirty-four patients (11%) had nonstroke conditions, with the most common being seizure (4%). The rate of administration of tissue plasminogen activator (tPA) for all patients with suspected stroke increased from 5.9% to 10.1% (p = 0.04) compared with the rate in the 12-month period prior to implementation of the acute stroke protocol. The tPA rate for patients arriving under the stroke protocol was 17.2%. Most patients (75%) receiving tPA arrived from outside the hospital catchment area.

Conclusions: In this preliminary study, the Ontario Prehospital Stroke Screening Tool had a high PPV for acute stroke and appeared to be effective for identifying patients who required triage to a single regional stroke center. Following implementation of a citywide acute stroke protocol using this screening tool, we observed an increase in the number of patients who were eligible for and received fibrinolysis at our stroke center.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acute Disease
  • Aged
  • Emergency Medical Services / methods*
  • Emergency Medical Services / statistics & numerical data
  • Female
  • Fibrinolysis*
  • Humans
  • Male
  • Mass Screening / methods*
  • Mass Screening / statistics & numerical data
  • Ontario
  • Predictive Value of Tests
  • Registries
  • Retrospective Studies
  • Stroke / diagnosis*
  • Stroke / prevention & control
  • Tissue Plasminogen Activator / therapeutic use*
  • Triage / statistics & numerical data


  • Tissue Plasminogen Activator