ABCD2 Score for TIA Stroke Risk
The ABCD2 score predicts the risk of stroke within 2 days and 7 days following a transient ischemic attack (TIA). Developed by Johnston et al. (2007), it is the most widely used risk stratification tool for TIA.
About
The ABCD2 score is a clinical prediction tool that incorporates Age, Blood pressure, Clinical features, Duration of symptoms, and Diabetes history to estimate short-term stroke risk after TIA. Scores range from 0-7, with higher scores indicating greater risk.
Formula
ABCD2 = Age(0-1) + BP(0-1) + Clinical(0-2) + Duration(0-2) + Diabetes(0-1)
The ABCD2 score is calculated by summing points from five clinical variables. Age ≥60 years contributes 1 point. Hypertension (SBP ≥140 mmHg or DBP ≥90 mmHg) contributes 1 point. Clinical features are scored as: unilateral weakness (2 points), speech impairment without weakness (1 point), or other (0 points). Duration of symptoms: ≥60 minutes (2 points), 10-59 minutes (1 point), or <10 minutes (0 points). Diabetes mellitus contributes 1 point. The total score ranges from 0 to 7, with risk stratification: 0-3 (low risk), 4-5 (moderate risk), and 6-7 (high risk). The score was derived from 4,909 patients in the Kaiser Permanente Northern California TIA cohort and validated in multiple independent populations. The c-statistic for 2-day stroke prediction is approximately 0.81 in the original validation.
Score Interpretation
The ABCD2 score helps clinicians triage TIA patients for urgent evaluation. High-risk patients (score 6-7) have an 8.1% 2-day stroke risk and require immediate hospitalization and workup. Low-risk patients can be evaluated urgently as outpatients. The score should be used alongside clinical judgment and neuroimaging. The ABCD2 score has been validated in multiple large cohort studies and is recommended by the American Heart Association (AHA) and National Stroke Association guidelines for TIA risk stratification. A key limitation is that the score does not incorporate neuroimaging findings — adding DWI-MRI positivity (ABCD2-I) improves risk prediction. The ABCD2 score performs best for anterior circulation TIAs and may underestimate risk in posterior circulation events.
Low Risk — 0–3
2-day stroke risk: 1.0%; 7-day stroke risk: 1.2%
Management: Urgent outpatient evaluation within 48 hours. Start aspirin 81 mg daily. Arrange outpatient carotid imaging and cardiac monitoring.
Moderate Risk — 4–5
2-day stroke risk: 4.1%; 7-day stroke risk: 5.9%
Management: Urgent evaluation within 24 hours. Start dual antiplatelet therapy (aspirin + clopidogrel) for 21 days. Urgent carotid imaging, ECG, and echocardiogram.
High Risk — 6–7
2-day stroke risk: 8.1%; 7-day stroke risk: 11.7%
Management: Emergency evaluation (within hours). Consider hospital admission for close monitoring and urgent workup. Start dual antiplatelet therapy. Urgent carotid imaging, cardiac monitoring, and full stroke workup.
Reference Ranges
| Population | Normal Range | Notes |
|---|---|---|
| TIA patients (Johnston et al. 2007 derivation cohort) | 0-7 points | 0-3 low risk, 4-5 moderate risk, 6-7 high risk. 2-day stroke risk: low 1.0%, moderate 4.1%, high 8.1%. 7-day stroke risk: low 1.2%, moderate 5.9%, high 11.7%. |
Dr. Mahmoud El-Sayed, MD, Neurology Specialist
Dr. Mahmoud El-Sayed is a neurology consultant with expertise in cerebrovascular disease and TIA management.
View medical review board & editorial policy →Example Calculation
A 70-year-old man with a history of hypertension and type 2 diabetes presents with acute onset of right-sided weakness and speech difficulty that lasted approximately 90 minutes and resolved completely. His blood pressure is 155/92 mmHg. ABCD2 score: Age ≥60 (+1), Hypertension (+1), Unilateral weakness (+2), Duration ≥60 minutes (+2), Diabetes (+1) = Total Score 7/7 (High Risk). This patient has an 8.1% risk of stroke within 2 days and 11.7% within 7 days. He requires emergency evaluation, hospital admission, dual antiplatelet therapy, urgent carotid imaging, and a full stroke workup including ECG, echocardiogram, and basic labs.
Related Conditions
Related Medications
Common Mistakes
Confusing the ABCD2 score with the NIH Stroke Scale (NIHSS)
ABCD2 is a risk stratification tool for TIA patients to predict short-term stroke risk. NIHSS quantifies neurological deficit severity in acute stroke. ABCD2 is for TIA (resolved symptoms), NIHSS is for ongoing stroke deficits.
Not counting duration of symptoms correctly — using time since onset rather than duration of the episode
Duration refers to how long the TIA symptoms lasted from onset to complete resolution, not how long ago they occurred. A TIA lasting 90 minutes (now resolved 2 hours ago) should be scored as ≥60 minutes (2 points), not based on the 2 hours since resolution.
Frequently Asked Questions
What is a transient ischemic attack (TIA)?
When should a patient with TIA be hospitalized?
References
- Johnston SC, Rothwell PM, Nguyen-Huynh MN, et al. Validation and refinement of scores to predict very early stroke risk after transient ischaemic attack. Lancet. 2007;369(9558):283-292. PubMed
- Johnston SC, Gress DR, Browner WS, et al. Short-term prognosis after emergency department diagnosis of TIA. JAMA. 2000;284(22):2901-2906. PubMed
- Rothwell PM, Giles MF, Flossmann E, et al. A simple score (ABCD) to identify individuals at high early risk of stroke after transient ischaemic attack. Lancet. 2005;366(9479):29-36. PubMed