How to Grade a TIA

Summarized by Robert W. Griffith, MD
May 8, 2006

Introduction

It's quite likely that people who have had a transient ischemic attack - a TIA - will subsequently have a full-blown stroke. The risk has been estimated at about 12% in the first year, and about 7% a year thereafter. And it may be as high as 10% in the first 7 days after the TIA.

It would clearly be useful to know which patients are at the greatest risk, and which are less likely, to have a stroke after a TIA. To help with this, researchers at the Department of Neurology, University of Oxford, UK, have developed a simple scoring system. It allows patients who have had a TIA to be managed optimally, by showing how likely they would otherwise be to have a stroke.

What was done

Relevant data were extracted from several large studies done in the Oxford area in the previous years, comprising about 100,000 patients all together. Based on these data a scoring system was constructed.

The investigators only used factors that were shown to be independent predictors of a stroke in the 3 months following a TIA. These were age, main clinical features (e.g. weakness of movement, speech disturbance), duration of symptoms, presence of diabetes, and high blood pressure. Patients were classified and scored according to the following criteria:

ABCD	RISK FACTOR	SCORE
AGE	Age below 60	0
	Age 60 or above	1
BLOOD PRESSURE	Systolic BP above 140 mmHg, and/or diastolic BP 90 mmHg or higher	1
CLINICAL	One-sided weakness of face, arm, hand or leg	2
	Speech disturbance without weakness	1
DURATION	Symptoms lasted more than 60 minute	2
	Symptoms lasted 10 to 60 minutes	1
	Symptoms lasted less than 10 minutes	0

Two sets of patients were studied - the first was used to establish the scoring system, and the second to test and validate the system.

Results

There were 209 probable or definite TIAs in the first set of patients, and 190 in the second set. Using the second set, 19 of 20 strokes occurred in the 7 days following a TIA, and all these had a score of 5, or 6 on the ABCD system.

Based on the validation (second) set of patients, the likelihood of having a stroke in the 7 days following a TIA could be expressed as follows:

• Overall likelihood: 10.5%
• ABCD Score 3 or less: 0%
• ABCD Score 4: 2.2%
• ABCD Score 5: 16.3%
• ABCD Score 6: 35.5%

For patients with an ABCD Score of less than 5, the risk was 0.4%, or 1 in 250.

What this report means

This analysis and scoring system shows that the risk of stroke during the 7 days after a TIA appears to be highly predictable. Age over 60, high blood pressure, weakness or speech defect, and duration of symptoms beyond an hour are all serious conditions that increase the risk of stroke. Diabetes was thought likely to be a relevant factor, but it didn't emerge as one in this analysis.

Before this information is of use to the general public, they need to be aware of the symptoms and signs of a TIA. A recent survey has shown that, in fact, less than one in ten US people can correctly identify the symptoms of TIA, and the urgency of need to take these seriously. This makes it important that the critical signs of TIA (weakness or speech defect lasting an hour or more) are made widely known to everyone in their 60s and older.

Use of the ABCD scoring system is simple and fast. Primary care or emergency departments, and even call-in help lines, can use it to assess the urgency of response to patients. Specialists can triage waiting patients.

Finally, the likelihood of a subsequent stroke can help guide therapy. Aspirin, clopidogrel, anticoagulation for patients with atrial fibrillation, and maybe a statin drug can be considered if there is any risk at all. Assessment of the need for carotid endarterectomy can be prioritized. And patients with an ABCD Score of 6 should probably be admitted to hospital for a period so that, if a stroke ensues, thrombolytic therapy (TPA, or tissue-plasminogen activator) can be given within the first hour - an important, effective, treatment that helps preserve nerve cells.

Source

• A simple score (ABCD) to identify individuals at high early risk of stroke after transient ischaemic attack. PM. Rothwell, MF. Giles, E. Flossmann,  et al., Lancet, 2005, vol. 366, pp. 29--36

Related Links
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