ABCD² Score For TIA

The ABCD2 scoring system is a rapid clinical tool that helps estimate the initial risk of stroke in the first 48 hours after a transient ischemic attack (TIA). Johnston and colleagues reported the initial stroke rate in acute TIA patients by analyzing 6 cohorts including 4799 individuals evaluated within 48 hours of TIA onset. Clinicians made the initial TIA diagnosis, allowing the scale to be applicable outside of specialized stroke centers.

The Canadian Transient Ischemic Attack Score is a clinical tool that stratifies the seven-day stroke risk of patients, whether or not they undergo carotid endarterectomy or carotid artery stenting after presenting to the emergency department with a transient ischemic attack.
Studies have shown that this score more accurately predicts the likelihood of stroke within seven days of a transient ischemic attack than the ABCD² and ABCD²I scores.

The ABCD2 is Calculated as Follows:

Age: ≥60 years: 1 point; <60 years: 0 points
Blood pressure at first assessment after TIA: systolic ≥140 mmHg or diastolic ≥90 mmHg: 1 point; systolic <140 mmHg and diastolic <90 mmHg: 0 points
Clinical features: unilateral weakness: 2 points; speech disorder only: 1 point; Other symptoms: 0 points
TIA symptom duration: ≥60 minutes: 2 points; 10–59 minutes: 1 point; <10 minutes: 0 points
Diabetes: present: 1 point; absent: 0 points

Annually, approximately 240,000 TIAs are recognized in the United States [1]. TIA-related admissions account for approximately 0.3% of all ED (emergency department) visits [2], and approximately 23% of strokes occur in patients with a prior TIA [3]. Recent research has shown that rapid evaluation and rapid ED-initiated treatment and diagnostic protocols within 24 hours can significantly reduce the rate of post-TIA stroke [4-6].

The immediate risk of stroke after TIA is much higher than previously recognized and exceeds the short-term risk of recurrent stroke. After stroke, the 30-day stroke risk is approximately 1.5% (CI 0.6-2.5) [7], while after TIA, the risk of stroke reaches 3.1% (95% CI 2.0-4.1) at 2 days and 5.2% (3.9-6.5) at 7 days [8]. In recent years, three clinical prediction tools (ABCD, California, and ABCD2) (Table 1) have been developed to estimate short-term stroke risk [9, 10]. Although initially designed for prognostic purposes, several studies have explored their diagnostic utility in TIA [11, 12]. These scoring systems rely on simple clinical data that clinicians can collect at the initial visit, including age, symptom type and duration, and the presence of elevated blood pressure or diabetes. However, these tools do not include other factors that also influence short-term stroke risk, such as diffusion-weighted imaging (DWI) abnormalities [13], large arterial stenosis [14], or atrial fibrillation [15].

Limitations of Existing Risk Scores

“However, this tool has struggled to effectively differentiate between low- and high-risk patients during prospective validation,” Jeffrey J. Perry, MD, MSc, CCFP-EM, professor in the Department of Emergency Medicine at the University of Ottawa, wrote with colleagues in The BMJ.

Several versions of the ABCD² score exist, including the ABCD²I score, which factors in brain infarction on neuroimaging.

Development and Validation of the Canadian TIA Score

To address this, researchers created the Canadian Transient Ischemic Attack Score, or Canadian TIA score. This scoring system assigns points based on multiple criteria: time to first transient ischemic attack; history of carotid stenosis, walking problems, unilateral weakness and dizziness; stroke symptoms lasting 10 minutes or more; Current use of antiplatelet medication; diastolic blood pressure of 110 mm/Hg or greater at initial triage; previous dysarthria or aphasia; atrial fibrillation on ECG; presence of new or old infarction on CT; platelet count of 400 x 10⁹/L or greater; and glucose level of 15 mmol/L or greater. Patients scoring -3 to 3 fall into the low-risk category for subsequent stroke; patients scoring 4 to 8 fall into the moderate-risk category; and scores of 9 to 23 indicate high risk for stroke within 1 week.

The researchers evaluated the Canadian TIA score in more than 7,000 adults (mean age 68.5 years; 52.4% women) with transient ischemic attack or minor stroke admitted to 13 Canadian emergency departments over a 5-year period. They excluded patients with neurological deficits lasting more than 24 hours, a Glasgow Coma Scale score of 15 or less, alternative diagnoses (such as electrolyte disturbances, migraine, hypoglycemia, or seizures), delayed ED presentation for 1 week or more, or treatment with tissue plasminogen activator or embolectomy. Of all “potentially eligible” individuals presenting to participating hospitals during the study, 80.6% of patients were included. Of the group, the Canadian TIA score classified 17% (n = 1,293) as low risk, 71% (n = 5,400) as moderate risk, and 13% (n = 989) as high risk.

FAQs