People Aged Over 75 in Atrial Fibrillation on Warfarin: The Rate of Major Hemorrhage and Stroke in More Than 500 Patient‐Years of Follow‐Up

OBJECTIVES: To determine the incidence of major hemorrhage and stroke in people aged 76 and older with atrial fibrillation on adjusted-dose warfarin who had been recently been admitted to hospital. DESIGN: A retrospective observational cohort study. SETTING: A major healthcare network involving four tertiary hospitals. PARTICIPANTS: Two hundred thirty-five patients aged 76 and older admitted to a major healthcare network between July 1, 2001, and June 30, 2002, with atrial fibrillation on warfarin were enrolled. MEASUREMENTS: Information regarding major bleeding episodes, strokes, and warfarin use was obtained from patients, relatives, primary physicians, and medical records. RESULTS: Two hundred twenty-eight patients (42% men) with a mean age of 81.1 (range 76-94) were included in the analysis. Total follow-up on warfarin was 530 years (mean 28 months). There were 53 major hemorrhages, for an annual rate of 10.0%, including 24 (45.3%) life-threatening and five (9.4%) fatal bleeds. The annual stroke rate after initiation of warfarin was 2.6%. CONCLUSION: The rate of major hemorrhage was high in this old, frail group, but excluding fatalities, resulted in no long-term sequelae, and the stroke rate on warfarin was low, demonstrating how effective warfarin treatment is.