Canadian TIA Score outperforms ABCD scores in predicting stroke

The Canadian Transient Ischaemic Score was more accurate than the ABCD² and ABCD²I scores in determining patients’ risk for a subsequent stroke within 7 days of having a minor one or a transient ischemic attack, recent data showed.

According to researchers, the ABCD² score is “the best-known score” for assessing stroke risk in patients with transient ischemic attack.

“However, this instrument has not been able to discriminate particularly well between groups at low and high risk during prospective validation,” Jeffrey J. Perry, MD, MSc, CCFP-EM, a professor in the department of emergency medicine at the University of Ottawa, and colleagues wrote in The BMJ.

There are several variations of the ABCD² score, including the ABCD²I score, which incorporates brain infarction on neuroimaging.

The researchers developed the Canadian Transient Ischaemic Score, or Canadian TIA Score. The score assigns various numbers of points to the following criteria: when the first transient ischemic attack occurred; past history of carotid stenosis, gait disturbances, unilateral weakness and vertigo; stroke symptoms that have lasted for 10 minutes or more; patient is already taking antiplatelet therapy, has a diastolic BP of 110 mm/Hg or higher at first triage; has a history of actual dysarthria or aphasia exams, has atrial fibrillation on his or her ECG, has a new or old infarction on their CT, has a platelet count of 400 x 10⁹/L or greater and a glucose level of 15 mmol/L or higher. Patients with scores of –3 to three are categorized as low risk for a subsequent stroke; those scores of four to eight points are considered at medium risk for a subsequent stroke; and those with nine to the maximum of 23 points are considered at high risk for having a stroke within 1 week.

The researchers tested the accuracy of the Canadian TIA Score on more than 7,000 consecutively enrolled adults (mean age, 68.5 years; 52.4% women) who presented with a transient ischemic attack or minor stroke to one of 13 Canadian EDs during a 5-year period. They excluded patients who had neurological deficits for more than 24 hours; Glasgow Coma Scale of 15 or less; an alternative diagnosis (eg, electrolyte imbalance, migraine, hypoglycemia and/or seizure); presented to the ED 1 week or more after neurological symptoms began; and/or were treated with tissue plasminogen activator or embolectomy for an acute stroke. The patients included the study accounted for 80.6% of all “potentially eligible” patients who presented at one of the participating hospitals during the course of the study, according to the researchers. Among the entire cohort, the Canadian TIA Score considered 17% (n = 1,293) of the patients as low risk, 71% (n = 5,400) as medium risk, and 13% (n = 989) as high risk.

Perry and colleagues reported that within 7 days, 1.4% (n = 108) of patients had another stroke, 1.1% (n = 83) had carotid endarterectomy/carotid artery stenting and less than 1% (n = 9) had both. The Canadian TIA Score “more accurately” stratified the risk for stroke, carotid endarterectomy/carotid artery stenting or both within 7 days as low (risk 0.5%; interval likelihood ratio [ILR] = 0.2; 95% CI, 0.09-0.44), medium (risk = 2.3%; ILR = 0.94; 95% CI, 0.85-1.04) and high (risk = 5.9%; ILR = 2.56; 95% CI, 2.02-3.25) compared with the other scores. The area under the curve was 0.7 (95% CI, 0.66-0.73) for the Canadian TIA score, 0.64 (95% CI, 0.59-0.68) for the ABCD²I score and 0.6 (95% CI, 0.55-0.64) for the ABCD² score. The risks for subsequent stroke were similar regardless of carotid endarterectomy/carotid artery stenting within 7 days, the researchers wrote.

“The Canadian TIA Score can now be safety used in emergency departments, where it can help physicians make the best care decisions for patients with mini-strokes,” Perry said in a press release.

The tool is available through The Ottawa Rules app, according to the press release.