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ABCD2 score not accurate enough to determine stroke risk after TIA

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – For assessing subsequent risk of stroke in patients who’ve had a transient ischemic attack, the so-called ABCD2 instrument is not sensitive or specific enough to have much clinical utility, a Canadian team has found.

The ABCD2 score (Age, Blood pressure, Clinical features, Duration of symptoms and Diabetes) is widely used to identify TIA patients who are at high risk for imminent stroke, but it has not been prospectively validated, explain Dr. Jeffrey J. Perry, at the University of Ottawa, Ontario, and colleagues in the .June 6 online issue of the Canadian Medical Association Journal.

They therefore conducted a prospective study of outcomes in 2056 patients diagnosed with a TIA in eight emergency departments. ABCD2 data were collected before patients were discharge or referred to a specialist.

On follow-up, 38 (1.8%) of the patients had a stroke within 7 days of being diagnosed with a TIA, and 65 (3.2%) patients had a stroke within 90 days, according to the report.

Correlating these outcomes to the ABCD2 scores, the researcher found that a “high-risk” score of more than 5 had a sensitivity of only 31.6% for predicting stroke at 7 days, and 29.2% for stroke at 90 days.

Using a cutpoint of more than 2 to classify moderate-to-high risk (as suggested by the American Heart Association) was highly sensitive (94.7%) but it had a very low specificity of 12.5%. In other words, based on that cutpoint, 87.5% of the TIA patients seen would be classified as requiring urgent investigation or hospitalization.

“This prospective study found that the high-risk ABCD2 score is not sensitive enough to be the sole guide for assessing risk for patients in emergency departments with transient ischemic attack.” Dr. Perry and colleagues conclude in their summary.

Furthermore, they add, “Using the current recommendation of the American Heart Association (i.e., an ABCD2 score of more than 2) does not discriminate well between patients at high and low risk, thus requiring urgent care for nearly all patients and thereby limiting its clinical utility.”

Reference:
Prospective validation of the ABCD2 score for patients in the emergency department with transient ischemic attack
CMAJ 2011.