TIA Risk Stratification with the Canadian TIA Score

Dr. Brandon Chang

edited by Ilyas Taraki

Background

Patients who have a transient ischemic attack (TIA) are known to be at high risk of subsequent stroke, especially in the week following the initial event. However, these patients are on a continuum from low to high risk. The ability to risk stratify a group of TIA patients for potential outpatient follow-up could be useful in low-resourced or strained hospital settings. An adequate scoring tool could allow patients to safely access outpatient care while decreasing inpatient admission and resource utilization. The recently validated Canadian TIA score presents an opportunity to do so and this study will evaluate its effectiveness and compare it to previous scoring tools.

Study Design

  • Prospective multicenter cohort study with 7607 enrolled patients with TIA

  • Performed at 3 community and 10 academic centers in Canada over 5 years

  • Enrolled those age >18 with diagnosis of TIA (or minor stroke)

  • Excluded those with neuro symptoms >24hrs, GCS <15, or alternate diagnosis

  • Follow-up phone calls at 7 and 90 days for subsequent events

  • Composite outcome of stroke or carotid revascularization within 7 days

Results

  • Of 7607 patients, only 34 (0.4%) lost to follow-up

    • 108 (1.4%) had subsequent stroke

    • 83 (1.1%) had carotid revascularization

    • 9 patients with both, giving total 182 outcomes

  • Most common presenting symptoms were sensory deficits, weakness, and speech difficulties

  • Risk stratification stroke, CEA/CAS

    • Low risk group: 0.5% (16% of patients)

    • Medium risk: 2.3% (72% of patients)

    • High risk: 5.9% (12% of patients)

Canadian TIA Score

  • Variables were established from a previous derivation study

  • Low risk is -3 to 3; medium risk is 4 to 8; high risk >9

  • Somewhat complicated score, with 13 different inputs

  • Previous ABCD2 score composed of age, blood pressure, clinical features, duration, diabetes history (ABCD2i included infarct on imaging)

  • Canadian TIA was much better compared to ABCD2/ABCD2i and was able to identify a low risk population (<1% risk of stroke in 7 days)

Conclusion

Overall, the Canadian TIA score has been validated for clinical use and is a much more useful scoring tool compared to the previous ABCD2/ABCD2i scoring tools. It also answered a clinically important question of identifying a low risk TIA population.

Strengths include a large study population as well as multiple practice settings. However, it is somewhat limited in its complexity (although utilization could be increased with EMR integration) and also regionality (this study was performed in Canada only). Per this study, a small, but not insignificant proportion of patients could be identified for outpatient follow-up.

Although it depends on the practice setting, health care resources, and ability to provide timely outpatient follow-up, this tool could be useful in low-resource environments to provide care for TIA patients.

References

Perry J J, Sivilotti M L A, Emond M, Stiell I G, Stotts G, Lee J et al. 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 :n49 doi:10.1136/bmj.n49