Stroke Risk Calculator (ABCD2 Score)

The ABCD2 score was developed in 2007 to predict stroke risk after a transient ischemic attack (TIA). A TIA is a temporary episode of neurological dysfunction caused by reduced blood flow, with symptoms that resolve within 24 hours. Despite the temporary nature of symptoms, TIA is a medical emergency because the days immediately following carry the highest stroke risk.

ABCD2 stands for: Age, Blood pressure, Clinical features, Duration of symptoms, and Diabetes. Each factor adds points to a total score of 0 to 7.

Interpretation by score: Low risk (0-3): 2-day stroke risk approximately 1%. 7-day risk approximately 1.2%. Moderate risk (4-5): 2-day stroke risk approximately 4%. 7-day risk approximately 5.9%. High risk (6-7): 2-day stroke risk approximately 8%. 7-day risk approximately 11.7%.

These are population-level risks from the original validation studies. Individual risk depends on many additional factors: imaging findings, atrial fibrillation, carotid stenosis, and whether antiplatelet therapy was started immediately.

The score should not be used to determine whether to admit or discharge a patient. Guidelines from the American Heart Association recommend urgent evaluation and treatment of all TIAs regardless of ABCD2 score. Workup includes brain imaging (MRI preferred), vascular imaging of the neck and intracranial vessels, cardiac monitoring, and blood tests.

The reason early treatment matters: antiplatelet therapy (aspirin, clopidogrel), statin initiation, and blood pressure control in the hours after TIA can reduce the subsequent stroke risk by 80% or more. Most of that risk reduction happens in the first 48 hours.