Transient ischemic attack and risk of stroke recurrence: The Lehigh Valley Recurrent Stroke Study.

We investigated the effect of transient ischemic attack occurring both before and after an initial stroke on risk of recurrent stroke in a population-based study. In the Lehigh Valley Recurrent Stroke Study, patients were enrolled between July 1987 and August 1989 and followed up regularly at about 6-month intervals for up to 4 years (mean, 2 years). In addition to history of transient ischemic attack before and after the initial stroke, information on comorbidities including hypertension, myocardial infarction, cardiac arrhythmia, and diabetes mellitus was collected at the baseline visit and at follow-up visits. The 621 patients with an initial ischemic stroke constituted the cohort analyzed in this report. A history of transient ischemic attack was present at enrollment in 114 (18.4%) patients. During follow-up, 20 patients experienced a transient ischemic attack, and 77 had a recurrent stroke. Using a Cox proportional hazards model taking comorbidities, sex, and age into account, we analyzed the relationship between transient ischemic attack and recurrent stroke in the 503 patients with at least one follow-up visit. History of transient ischemic attack before the initial stroke was associated with a decreased risk of recurrent stroke (Hazards ratio, 0.3; 95% confidence interval, 0.08 to 0.86; P=.03), whereas a new transient ischemic attack after the initial stroke was associated with an increased risk of recurrent stroke (Hazards ratio, 11.7; 95% C.I. confidence interval=3.45 to 39.83; P=.0001).