The ABCD and ABCD2 as predictors of stroke in transient ischemic attack clinic outpatients: a retrospective cohort study over 14 years

BACKGROUND: The ABCD and ABCD2 scores have been validated for use as predictors of stroke in community populations up to 90 days after a transient ischemic attack (TIA). TIA outpatient clinics may see a selective group of patients who have not had an early stroke but may be at raised risk in the medium to long term and therefore benefit from preventive treatment. AIM: To describe the prognostic values of the ABCD and ABCD2 scores on long-term stroke risk. DESIGN: Retrospective cohort study of TIA clinic outpatients followed for up to 14 years. METHODS: Absolute and relative stroke risks, Kaplan-Meier survival curves and cumulative stroke incidence were calculated. Receiver Operating Characteristic curves (ROCs) and areas under the curve were calculated for both scores. RESULTS: Seven hundred and ninety-five patients were included and 138 (17.3%) experienced a stroke within 13.8 years follow-up after first TIA clinic visit, a crude risk of 26.3 per 1000 person-years. Compared with baseline scores of 0-2, risk ratios for ABCD of 3-4 were 2.95 (95% CI 1.52-6.40), and for 5-6 were 3.42 (95% CI 1.72-7.54); for the ABCD2, risk ratios for 3-4 were 2.68 (95% CI 1.37-5.84), and for 5-7 were 3.55 (95% CI 1.80-7.79). Scores of > or = 3 for either ABCD or ABCD2 predicted raised stroke risks at 90 days, 1, 5 and 10 years. Areas under the curve were 0.619 (95% CI 0.571-0.668) and 0.630 (95% CI 0.582-0.677) for the ABCD and ABCD2 scores, respectively. CONCLUSION: ABCD and ABCD2 scores of > or = 3 may be clinically useful in identifying TIA outpatients at raised risk of stroke in the medium to long term.