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Q Can a simple risk score predict stroke during the first 7 days after probable or definite transient ischaemic attack (TIA)?
3 cohort studies: a derivation cohort (Oxfordshire Community Stroke Project [OCSP]) and 2 independent validation cohorts (2 cohorts from the Oxford Vascular Study [OXVASC] and a cohort of patients referred to a hospital based TIA clinic).
10 family practices in Oxfordshire, UK (OCSP and OXVASC cohorts) and a hospital based TIA clinic.
209 patients (mean age 70 y) with a first ever probable or definite TIA (OCSP derivation cohort); 190 patients (mean age 74 y) with probable or definite TIA and 378 patients (mean age 70 y) with suspected TIA (OXVASC validation cohorts); and 210 patients (mean age 65 y) referred to the hospital clinic with suspected TIA (clinic validation cohort).
Description of prediction guide:
analysis of predefined risk factors in the derivation cohort found that age ⩾60 years, clinical features, symptom duration, and elevated blood pressure (BP) at presentation were predictive of stroke (p⩽0.1); diabetes and previous diagnosis of hypertension were not. The resulting risk score, termed the ABCD (age, BP, clinical features, and duration) score, therefore included age (⩾60 y = 1), BP (>140 mm Hg systolic or ⩾90 mm Hg diastolic = 1), clinical features (unilateral weakness = 2, speech disturbance without weakness = 1, other = 0), and duration of symptoms (⩾60 min = 2, 10–59 min = 1, <10 min = 0).
7 day risk of stroke.
7 day stroke risk was 8.6% in OSCP cohort, 10.5% in the OXVASC (probable or definite TIA) cohort, 5.3% in the OXVASC (suspected TIA) cohort, and 6.7% in the clinic (suspected TIA) cohort. The distributions of ABCD scores in the validation cohorts are presented in the table. The areas under the receiver operating characteristic curve were 0.85 (95% CI 0.78 to 0.91) in the OXVASC (probable or definite TIA) cohort, 0.91 (CI 0.86 to 0.95) in the OXVASC (suspected TIA) cohort, and 0.80 (CI 0.72 to 0.89) in the clinic (suspected TIA) cohort. The scores in the latter 2 cohorts remained predictive when excluding strokes that occurred before patients sought medical attention (p⩽0.01).
In patients with transient ischaemic attack, a simple risk score based on age, blood pressure, clinical features, and duration of symptoms predicted 7 day stroke risk.
A modified version of this abstract appears in ACP Journal Club.
In the rapidly expanding field of secondary stroke prevention, TIA clinics represent a relatively new service, designed to provide early access to diagnostic tests and treatment for patients at high risk of stroke. Patients with neurological symptoms suggesting stroke risk may be referred from emergency departments and family physicians. As clinics become established, rapidly increasing referrals challenge their responsiveness and limited resources.
The ABCD tool developed by Rothwell et al provides referring physicians and clinic nurses with a valuable triage tool to predict (1) those who require immediate attention in the form of hospital admission at the time of initial symptom occurrence; (2) those who require semi-urgent access to clinic services; and (3) those who may be seen in the clinic non-urgently or more appropriately by other healthcare teams. The score also provides a simple tool with which to communicate risk among professional groups and to patients and families.
A standardised evidence-based approach to triage applied across healthcare sectors and professional providers has potential to ensure that prevention clinics will continue to meet the urgent needs of those at high risk of stroke. The use of a validated triage tool would provide healthcare professionals with confidence that their assessments will not put patients at further risk. Given the mortality and morbidity associated with a major stroke event and the diversity of stroke expertise among providers, this is an important consideration. However, in order to implement the broad use of the ABCD tool, a considerable investment in professional education and marketing will be required.
Although the results reported by Rothwell et al indicate that a simple risk score predicted 7 day stroke risk in these populations, the study should be replicated in other geographic locations and at-risk stroke populations to ensure the generalisability of the findings. Studies are also needed to determine the feasibility of incorporating the tool in practice across sectors and professionals groups in various healthcare delivery systems (public and private).
For correspondence: Professor P M Rothwell, University of Oxford, Radcliff Infirmary, Oxford, UK.
Sources of funding: UK Stroke Association; BUPA Foundation; UK Medical Research Council.
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