Frequency of major complications of aspirin, warfarin, and intravenous heparin for secondary stroke prevention: A population-based study

Background: Complication rates of medical therapy for secondary stroke prevention derived from clinical trials may or may not be applicable to patients with cerebrovascular disease in the general population. Objective: To determine complication rates for aspirin, warfarin, and intravenous heparin administered for secondary stroke prevention after first episodes of ischemic stroke, transient ischemic attack, or amaurosis fugax in a community. Design: Population-based historical cohort study. Setting: Rochester, Minnesota. Patients: All residents of Rochester who, between 1985 and 1989, received aspirin (n = 339) or warfarin (n = 145) within 2 years after first ischemic stroke, transient ischemic attack, or amaurosis fugax or received intravenous heparin (n = 201) within 2 weeks after first ischemic stroke, transient ischemic attack, or amaurosis fugax. Measurements: Occurrence of major complications caused by therapy. Results: Twenty aspirin- associated complications (1 fatal) occurred during an average 1.7 years of treatment, 8 warfarin-associated complications occurred during an average 0.7 years of treatment, and 3 heparin-associated complications (1 fatal) occurred during an average 5.1 days of treatment. Complication rates were 3.5 per 100 person-years (95% CI, 2.1 to 5.4) for aspirin, 7.9 per 100 person-years (Cl, 3.4 to 15.6) for warfarin, and 0.30 (Cl, 0.06 to 0.86) per 100 person-days for heparin. Rates of fatal complications were 0.2 per 100 person-years (Cl, 0 to 1.0) for aspirin, 0 per 100 person-years (Cl, 0 to 3.6) for warfarin, and 0.10 per 100 person-days (0 to 0.55) for heparin. Conclusions: Complication rates for warfarin and intravenous heparin given as therapy for secondary stroke prevention in Rochester, Minnesota, were lower than rates reported from earlier trials and observational studies. However, complication rates for warfarin were higher than in more recent referral-based studies and multicenter randomized trials. After adjustment for duration of therapy, complication rates for heparin were higher than those for aspirin or warfarin. These rates can be used to judge the applicability of complication rates derived from ongoing clinical trials.