ABCD2 leaves out the things that actually cause early recurrence — atrial fibrillation, carotid disease, infarction already visible on CT. The Canadian TIA Score was derived and prospectively validated to fix exactly that, and in head-to-head comparison it separated high-risk from low-risk patients better than ABCD2 did.1

At a glance · what the score changes

  • ≤3 · about 0.5% stroke within 7 days. Consistent with outpatient management and primary-care follow-up — arranged deliberately. Low risk is not no risk.
  • 4–8 · about 2.3%. Prompt investigations with specialist follow-up, typically within about two days.
  • ≥9 · about 5.9% — roughly twelvefold the low tier. Same-visit specialist consultation and expedited workup rather than scheduled follow-up.
  • A tier is not a disposition. The score grades how fast the workup should happen, not whether it happens.
  • It assumes an emergency-department evaluation with ECG, CT and bloodwork has already been done — several of its highest-weighted items are otherwise missing.

Why it beats ABCD2

Look at what the thirteen items include: atrial fibrillation on the ECG, known carotid stenosis, infarction already visible on CT, being on antiplatelet therapy despite which the event still happened. Those are mechanisms, not just demographics — and they are precisely what ABCD2 omits. In prospective multicentre validation, the Canadian TIA Score discriminated subsequent stroke risk better than ABCD2 and ABCD2i.1

One item runs the other way: a history of vertigo subtracts three points, because vertigo in this population more often reflects a peripheral vestibular cause than a cerebrovascular one. It is a useful reminder that the score is empirical — derived from what actually predicted stroke, not from what feels alarming.

Pitfall

The score was validated in patients who had already had an emergency-department evaluation including ECG, CT, and bloodwork. Applying it before that workup — over the phone, in a hallway, from a triage note — is using it outside the setting it was built for, and several of its highest-weighted items would simply be missing.

Reading the tiers

  • Low (≤3): about 0.5% stroke within 7 days.
  • Medium (4–8): about 2.3%.
  • High (≥9): about 5.9%.

The tiers are about tempo. They tell you whether this patient needs a clinic appointment arranged, a specialist within two days, or a consultation before they leave the building. Longer discussion of the score's derivation, its comparison with ABCD2, and what it does not settle is in the full Canadian TIA Score review.