ABCD² Score
Stroke risk stratification after transient ischemic attack (TIA)
Calculator
Why use it
Risk-stratifies TIA patients for urgent vs. outpatient workup. Identifies patients who need emergent imaging and hospital admission. Guides timing of carotid imaging and antiplatelet initiation.
About
The ABCD² score estimates the short-term risk (2, 7, and 90 days) of stroke following a transient ischemic attack. It uses five factors: Age, Blood pressure, Clinical features, Duration of symptoms, and Diabetes to stratify patients into risk categories and guide urgency of evaluation.
When to use
- After confirmed or suspected TIA
- ED disposition decisions for TIA patients
- Determining urgency of neurology consultation and imaging
Formula
Pearls & pitfalls
- ABCD² should NOT be used alone to decide on discharge — all TIA patients need urgent workup.
- AHA/ASA recommends evaluation within 24-48 hours for all TIA patients regardless of score.
- Additional high-risk features not in ABCD²: dual TIA (crescendo), AF, carotid stenosis, DWI positive.
- The score does not account for etiology — always investigate underlying cause.
- Combination with imaging (DWI-MRI, carotid imaging) improves risk prediction.
Next steps
Score 0-3: Low risk (~1% 2-day stroke risk). Score 4-5: Moderate risk (~4%). Score 6-7: High risk (~8%). All TIA patients need urgent workup; high-score patients need admission and emergent evaluation.
Evidence
Derived and validated by Johnston et al. (Lancet 2007) from pooled data of >4,800 TIA patients. 2-day stroke risk ranges from 1% (score 0-3) to 8.1% (score 6-7). Subsequent studies suggest ABCD² alone has limited ability to identify all high-risk patients.
References
- Johnston SC et al. Validation and refinement of scores to predict very early stroke risk after transient ischaemic attack. Lancet. 2007;369(9558):283-292. — link