Canadian TIA Score Calculator: A Sharper Read on Stroke Risk After a TIA

Every emergency department has had the same uncomfortable conversation at 2 a.m.: a patient whose slurred speech and arm weakness melted away in the waiting room, a normal exam by the time you see them, and a decision that suddenly feels heavier than the tidy chart makes it look. Did the storm pass, or was it the first flash of lightning? The point of a TIA risk score is not to answer that with false confidence — it is to put a number on the uncertainty so the next few days are organized around the right level of urgency. The Canadian TIA Score was built for exactly that moment, and it does the job with more precision than the older ABCD2.¹

Interactive tool

Canadian TIA Score Calculator

Answer each item for a patient presenting with a suspected TIA. The score and 7-day risk tier update instantly.

First TIA in lifetimeNoYes +2

Symptoms lasted 10 minutes or moreNoYes +2

History of carotid stenosisNoYes +2

Already on antiplatelet therapyNoYes +3

History of gait disturbanceNoYes +1

History of unilateral weaknessNoYes +1

History of vertigoNoYes −3

Initial triage diastolic BP 110 mmHg or higherNoYes +3

Dysarthria or aphasiaNoYes +1

Atrial fibrillation on ECGNoYes +2

Infarction (new or old) on CTNoYes +1

Platelet count 400 × 10⁹/L or higherNoYes +2

Glucose 15 mmol/L or higher 270 mg/dLNoYes +3

0 points

Low risk

Educational tool only. The Canadian TIA Score supports triage; it does not replace clinical judgment, imaging, or in-person evaluation, and it is not a discharge rule. If you may be having stroke symptoms now, call emergency services. Risk estimates from Perry et al., BMJ 2021.¹

What the score is actually reading

The reason ABCD2 has slowly fallen out of favor is not that its five ingredients are wrong — age, blood pressure, the type of deficit, how long it lasted, diabetes — but that they leave out the mechanisms most likely to throw a second, bigger clot in the next few days. The Canadian TIA Score was derived and validated to fix that. It keeps the clinical picture but adds the evidence sitting in front of you: the ECG, the CT, the platelet count and glucose, and crucially, whether the patient was already on antiplatelet therapy when the event happened.¹

That last variable is quietly the most interesting. Having a TIA despite being on aspirin or clopidogrel is a signal that the usual defense has already been breached — and it carries three points, the joint-highest weighting in the score. It is the kind of clinical common sense that a purely demographic score never captures.

The thirteen variables

Each item adds points, with one deliberate exception. The score runs from a small negative number up into the twenties, and the total is what maps onto the risk tiers.¹

• +3 points: already on antiplatelet therapy; triage diastolic BP ≥ 110 mmHg; glucose ≥ 15 mmol/L (270 mg/dL).
• +2 points: first TIA in lifetime; symptoms lasting ≥ 10 minutes; history of carotid stenosis; atrial fibrillation on ECG; platelets ≥ 400 × 10⁹/L.
• +1 point: history of gait disturbance; history of unilateral weakness; dysarthria or aphasia; infarction (new or old) on CT.
• −3 points: a history of vertigo — the one item that lowers the score, because isolated vertigo more often reflects a peripheral cause than a cerebrovascular one.

What each tier is really telling you to do

The score earns its keep by translating into tempo. In the validation cohort of more than 7,000 patients across thirteen emergency departments, the three tiers carried clearly separated 7-day stroke risks — and, just as usefully, a matching intensity of follow-up.¹

• Low (≤ 3): roughly 0.5% 7-day stroke risk. Reasonable for outpatient management with primary-care follow-up — arranged, not assumed.
• Medium (4–8): roughly 2.3%. Investigations with specialist follow-up inside a couple of days.
• High (≥ 9): roughly 5.9%. Same-visit consultation and expedited workup before the patient leaves your sight.

Why it reads risk better than ABCD2

This is not a matter of taste. In the prospective validation, the Canadian TIA Score discriminated subsequent stroke substantially better than ABCD2, with an area under the curve of 0.70 versus 0.60 — a meaningful gap in a decision where the cost of under-calling is a completed stroke.¹ The improvement comes from exactly the variables ABCD2 omits: atrial fibrillation, carotid disease, infarction on imaging, and the antiplatelet-failure signal. It is a more honest reflection of how a TIA actually becomes a stroke.

None of this makes ABCD2 useless — it remains fast, memorable, and embedded in the dual-antiplatelet trial criteria (its 4-or-more threshold still lives in CHANCE and POINT).² But if the question is purely how likely is a stroke in the next week, the Canadian score answers it with a sharper instrument.

Where it fits, and where it stops

Use it the way it was designed: to calibrate urgency once you already believe the event was a TIA, and to structure the pace of the workup and follow-up. Do not use it to decide whether a suspected TIA deserves evaluation at all — every one does, and current secondary-prevention guidance still turns on imaging the brain and its vessels and checking the heart rhythm regardless of any score.³ The score is the tempo marking on the page. The clinician is still the one playing the music.