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Prospective validation of Canadian TIA Score and comparison with ABCD2 and ABCD2i for subsequent stroke risk after transient ischaemic attack: multicentre prospective cohort study

BMJ 2021; 372 doi: (Published 04 February 2021) Cite this as: BMJ 2021;372:n49
  1. Jeffrey J Perry, professor1 2,
  2. Marco L A Sivilotti, professor3,
  3. Marcel Émond, associate professor4 5,
  4. Ian G Stiell, professor1 2,
  5. Grant Stotts, assistant professor6,
  6. Jacques Lee, assistant professor7 8,
  7. Andrew Worster, professor9,
  8. Judy Morris, associate professor10,
  9. Ka Wai Cheung, clinical associate professor11,
  10. Albert Y Jin, associate professor12,
  11. Wieslaw J Oczkowski, associate professor13,
  12. Demetrios J Sahlas, associate professor13,
  13. Heather E Murray, professor3,
  14. Ariane Mackey, associate professor4 14,
  15. Steve Verreault, clinical professor4 14,
  16. Marie-Christine Camden, assistant professor4 14,
  17. Samuel Yip, assistant professor15,
  18. Philip Teal, clinical professor15,
  19. David J Gladstone, associate professor16,
  20. Mark I Boulos, assistant professor16,
  21. Nicolas Chagnon, assistant professor17,
  22. Elizabeth Shouldice, assistant professor18,
  23. Clare Atzema, associate professor8,
  24. Tarik Slaoui, assistant professor10,
  25. Jeanne Teitlebaum, associate professor10,
  26. Kasim E Abdulaziz, methodologist2,
  27. Marie-Joe Nemnom, methodologist2,
  28. George A Wells, professor2,
  29. Mukul Sharma, associate professor13
  1. 1Department of Emergency Medicine, University of Ottawa, Ottawa, ON, Canada
  2. 2Ottawa Hospital Research Institute, Ottawa, ON, Canada
  3. 3Department of Emergency Medicine, Queen’s University, Kingston, ON, Canada
  4. 4CHU de Québec, Hôpital de l'Enfant-Jésus, Québec City, QC, Canada
  5. 5Division of Emergency Medicine, Université Laval, Québec City, QC, Canada
  6. 6Division of Neurology, Department of Medicine, University of Ottawa, Ottawa, ON, Canada
  7. 7Schwartz\Reisman Emergency Medicine Institute, Mount Sinai Hospital, Toronto, ON, Canada
  8. 8Department of Emergency Medicine, Sunnybrook Health Sciences Centre, Toronto, ON, Canada
  9. 9Division of Emergency Medicine, McMaster University, Hamilton, ON, Canada
  10. 10Hôpital du Sacré-Cœur de Montréal, Université de Montréal, Montréal, QC, Canada
  11. 11Department of Emergency Medicine, University of British Columbia, Vancouver, BC, Canada
  12. 12Division of Neurology, Queen’s University, Kingston, ON, Canada
  13. 13Division of Neurology, McMaster University, Hamilton, ON, Canada
  14. 14Division of Neurology, Laval University, Quebec City, QC, Canada
  15. 15Division of Neurology, University of British Columbia, Vancouver, BC, Canada
  16. 16Sunnybrook Research Institute and Division of Neurology, Department of Medicine, Sunnybrook Health Sciences Centre and University of Toronto, Toronto, ON, Canada
  17. 17Department of Emergency Medicine, Montfort Hospital and University of Ottawa, Ottawa, ON, Canada
  18. 18Queensway Carleton Hospital and University of Ottawa, Ottawa, ON, Canada
  1. Correspondence to: J J Perry jperry{at}
  • Accepted 9 December 2020


Objective To validate the previously derived Canadian TIA Score to stratify subsequent stroke risk in a new cohort of emergency department patients with transient ischaemic attack.

Design Prospective cohort study.

Setting 13 Canadian emergency departments over five years.

Participants 7607 consecutively enrolled adult patients attending the emergency department with transient ischaemic attack or minor stroke.

Main outcome measures The primary outcome was subsequent stroke or carotid endarterectomy/carotid artery stenting within seven days. The secondary outcome was subsequent stroke within seven days (with or without carotid endarterectomy/carotid artery stenting). Telephone follow-up used the validated Questionnaire for Verifying Stroke Free Status at seven and 90 days. All outcomes were adjudicated by panels of three stroke experts, blinded to the index emergency department visit.

Results Of the 7607 patients, 108 (1.4%) had a subsequent stroke within seven days, 83 (1.1%) had carotid endarterectomy/carotid artery stenting within seven days, and nine had both. The Canadian TIA Score stratified the risk of stroke, carotid endarterectomy/carotid artery stenting, or both within seven days as low (risk ≤0.5%; interval likelihood ratio 0.20, 95% confidence interval 0.09 to 0.44), medium (risk 2.3%; interval likelihood ratio 0.94, 0.85 to 1.04), and high (risk 5.9% interval likelihood ratio 2.56, 2.02 to 3.25) more accurately (area under the curve 0.70, 95% confidence interval 0.66 to 0.73) than did the ABCD2 (0.60, 0.55 to 0.64) or ABCD2i (0.64, 0.59 to 0.68). Results were similar for subsequent stroke regardless of carotid endarterectomy/carotid artery stenting within seven days.

Conclusion The Canadian TIA Score stratifies patients’ seven day risk for stroke, with or without carotid endarterectomy/carotid artery stenting, and is now ready for clinical use. Incorporating this validated risk estimate into management plans should improve early decision making at the index emergency visit regarding benefits of hospital admission, timing of investigations, and prioritisation of specialist referral.


  • Contributors: JJP had the idea for the study and prepared the manuscript. GAW provided statistical assistance and revised the manuscript. MS and IGS provided input into the study design and revision of the manuscript. MJN assisted with the statistical analysis. MLAS, MÉ, AW, GS, JM, JL, AYJ, WJO, KWC, DJS, HEM, AM, SV, TS, JT, PT, SY, MCC, DJG, MIB, KA, NC, ES, and CA assisted with study design and revised the manuscript. The corresponding author attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted. JJP is the guarantor.

  • Funding: The study was funded by the Canadian Institutes of Health Research. The funder had no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; and in the decision to submit the article for publication. Researchers are independent from funders, and all authors, external and internal, had full access to all of the data (including statistical reports and tables) in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis.

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at and declare: the study was funded by the Canadian Institutes of Health Research; JJP is supported by a mid-career award from the Heart and Stroke Foundation of Ontario; JL is supported by the Schwartz/Reisman Emergency Medicine Institute inaugural research chair in geriatric emergency medicine; no other relationships or activities that could appear to have influenced the submitted work.

  • Ethical approval: The study was approved by the research ethics board at each site as meeting the requirements for a waiver of written informed consent. Verbal consent was obtained at the time of each telephone call for patients contacted for follow-up.

  • Data sharing: Requests for sharing of the data will be considered and reviewed by the study’s steering committee. Requests can be made to the corresponding author.

  • The lead author affirms that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.

  • Dissemination to participants and related patient and public communities: There is no formal plan to disseminate these results to study participants. All study sites have received study results. The results of this work will be disseminated through social media, conferences, and creation of an infographic. The results will be incorporated in the Ottawa Rules App, which will assist clinicians using the score.

  • Provenance and peer review: Not commissioned; externally peer reviewed.

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