VALIDATION OF THE ACAS TIA STROKE ALGORITHM

Background and purpose: An easily administered questionnaire and algor ithm classifying transient ischemic attacks (TIAs) or strokes, and als o their distribution, could be invaluable for identifying endpoints in epidemiologic studies or clinical trials of prevention and therapy of cerebral ischemia. The Asymptomatic Carotid Atherosclerosis Study (AC AS) devised a symptom-based questionnaire and algorithm for detecting events in the trial. The purpose of this study was to determine sensit ivity, specificity, and agreement rates of the questionnaire and algor ithm against diagnoses of a panel of cerebrovascular disease authoriti es. Methods: Three hundred eighty-one men and women at eight medical c enters reported symptoms of stroke, TIA, or other neurologic illness. The questionnaire Mas administered by trained interviewers and the res ponses were analyzed using the algorithm. A standardized neurologic Ex amination was performed by a neurologist. Data were submitted to two o r more external reviewers, Sensitivity, specificity, and the kappa sta tistic (k) were used to evaluate the relationship between the algorith m and the external reviewers' diagnosis. Results: Of the 381 reviews: 196 were diagnosed as TIA or stroke by the external panel. The algorit hm's agreement with the diagnosis of TIA or stroke was 80.1%, and kapp a was 0.60. Sensitivity was 87.8%, and specificity was 71.9%. Conclusi on: While statistical agreement rates depend on the method of sample s election, the algorithm has a high agreement with an external panel of experts and is a sensitive tool for event detection. The lower specif icity indicates that careful neurologic evaluation may be required to confirm or refute events identified by the screening algorithm.