The ABCD2 score is a validated tool to estimate the risk that any given transient ischaemic attack (TIA) will progress into a completed stroke, helping to determine the urgency with which a patient needs specialist assessment and treatment.
It is well recognised that stroke has a large and ever increasing mortality and morbidity burden on patients. Despite newer treatments, there are still 120,000 strokes a year in the UK – mortality remains significant and there are estimated to be 1.2 million people living with the after effects of this disease. Given the importance of stroke prevention; the rapid identification, assessment and treatment of patients with a warning TIA remains an understandable priority.
When to use it
The ABCD2 score should be used once it has been determined that a possible TIA event has occurred in primary care. The ABCD2 score is not intended to be diagnostic – that depends mainly on the history of the event rather than any tool or investigations – but it determines the risk of progressing to a stroke.
Patients who reach 4 or more on the ABCD2 score should be deemed high risk and be seen in a specialist clinic within 24 hours. Once there, the diagnosis should be confirmed and appropriate treatment and investigations undertaken including, where relevant, carotid scanning and brain imaging.
Patients who score less than 4 are deemed low risk, but still should be seen within one week in a specialist clinic with access to the same assessment and investigations if relevant.
The ABCD2 Score
|A||Age >60 years||1|
|B||Blood pressure >140 mmHg systolic or >90 mmHg diastolic (generally accepted as blood pressure when seen and referred)||1|
Unilateral weakness (motor)
Speech disturbance without any weakness
Symptom duration > 60 minutes
< 10 minutes
Patients who have two or more events in a week, or are in atrial fibrillation, or on anticoagulants, should be considered high risk regardless of the score. Conversely, patients whose TIA event was over a week prior to presenting should be deemed as being low risk, again regardless of the actual score, and therefore should be seen within a week.
All patients should be given 300 mg of either aspirin or clopidogrel as a loading dose and then 75 mg subsequently, on presentation and prior to assessment in TIA clinic. They should also receive simvastatin 40mg and be advised not to drive. Ongoing treatment can then be decided after diagnosis in a specialist clinic.
Cautions in the use of the tool
One limitation of the tool is in its use in those patients with persistent stroke symptoms. It is validated for acute TIA, and therefore by definition in patients whose symptoms have fully resolved not stroke patients. This is important because the guidelines recommend rapid initiation of antiplatelets before brain imaging. The full resolution of symptoms is taken as an indication this is a transient ischaemic event and not a minor haemorrhagic event or other non-ischaemic pathology. In fact, brain imaging may not be undertaken even in TIA clinic because if there is no diagnostic doubt and the vascular territory (anterior or posterior circulation) is clear, it is not necessarily indicated. Clearly the administration of antiplatelets to intracerebral haemorrhages or brain tumours has the potential for harm.
Dr Don Sims is a consultant stroke physician and clinical service lead for stroke medicine at University Hospitals Birmingham NHS Foundation Trust.
- Johnston SC, Rothwell PM, Nguyen-Huynh MN, Giles MF, Elkins JS, Bernstein AL, Sidney S. (2007) Lancet, 369; 283-292