Background: Large intervention studies suggest that aspirin may reduce mortality when given to patients who present with strokes or transient ischemic attacks. We sought to determine whether patients who were already using aspirin at the time of an ischemic stroke had a lower mortality than those who were not.
Methods: A prospective cohort study was undertaken in patients (mean age 76 +/- 15 years) with acute ischemic stroke. Detailed information on demography, stroke characteristics, and aspirin use prior to the stroke was collected from patients, medical records, and other sources. Patients were classified by cause and subtype of stroke using standard criteria. Mortality was measured 4 weeks after the initial episode.
Results: Of the 1,457 patients, 650 (45%) were using aspirin (median dose 75 mg; range 75 to 300 mg) prior to the stroke. Prior use of aspirin was associated with lower 4-week mortality (14% versus 20%, P <0.01 ). Beneficial effects of prior aspirin use on mortality were seen in patients with atherosclerotic strokes (15% versus 21%, P <0.05) and with cardioembolic strokes (21% versus 34%, P <0.05), but not among patients with strokes due to small vessel occlusion (10% versus 11%, P = 0.8). Prior aspirin use was also associated with lower mortality in patients in whom the cause of ischemic stroke could not be determined (15% versus 22%, P <0.01). The effect of prior aspirin use on mortality was independent of age, gender, other risk factors, and use of other medication.
Conclusions: Prior use of low-dose aspirin may be associated with a small but significant reduction in stroke mortality.