title: Predictive value of the Ontario prehospital stroke screening tool for the identification of patients with acute stroke.
abstract: 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.
authors.affiliation: Division of Emergency Medicine, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Jordan
authors.initials: J
authors.lastname: Chenkin
authors.forename: David J
authors.initials: DJ
authors.lastname: Gladstone
authors.forename: P Richard
authors.initials: PR
authors.lastname: Verbeek
authors.forename: Patrice
authors.initials: P
authors.lastname: Lindsay
authors.forename: Jiming
authors.initials: J
authors.lastname: Fang
authors.forename: Sandra E
authors.initials: SE
authors.lastname: Black
authors.forename: Laurie
authors.initials: L
authors.lastname: Morrison
mesh_terms: D000208:Acute Disease; D000368:Aged; D004632:Emergency Medical Services / Q000379:methods* / Q000706:statistics & numerical data; D005260:Female; D005342:Fibrinolysis; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods* / Q000706:statistics & numerical data; D009864:Ontario; D011237:Predictive Value of Tests; D012042:Registries; D012189:Retrospective Studies; D020521:Stroke / Q000175:diagnosis* / Q000517:prevention & control; D010959:Tissue Plasminogen Activator / Q000627:therapeutic use*; D014218:Triage / Q000706:statistics & numerical data
chemical_list: D010959:Tissue Plasminogen Activator