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(Circulation. 2005;111:2250-2256.)
© 2005 American Heart Association, Inc.

Stroke

Prognostic Implications of Warfarin Cessation After Major Trauma

A Population-Based Cohort Analysis

From the Division of Clinical Pharmacology (D.G.H.) and the Institute for Clinical Evaluative Sciences (D.G.H., A.K., D.A.R.), University of Toronto, and the Department of Health Policy, Management and Evaluation and Department of Medicine (D.G.H., D.A.R.), Sunnybrook & Women’s College Health Sciences Centre, Toronto, Canada.

Correspondence to Dr Donald Redelmeier, Room G-151, Sunnybrook & Women’s College Health Sciences Centre, 2075 Bayview Ave, Toronto, ON, Canada, M4N 3M5. E-mail dar{at}ices.on.ca

Received September 13, 2004; revision received January 13, 2005; accepted January 19, 2005.

Background— Warfarin therapy is often withheld from elderly patients who fall or otherwise experience injury because of concerns regarding the long-term risk of hemorrhage in these individuals. We studied whether stopping warfarin after trauma is associated with a higher risk of subsequent adverse cardiovascular events.

Methods and Results— We conducted a retrospective, population-based, cohort study using linked administrative databases in the province of Ontario, Canada for the years 1992 to 2001. A total of 8450 elderly patients (age >65 years) who survived an incident of major trauma and were receiving warfarin before injury were followed up for a mean of 3.3 years. During the 6-month interval after trauma, 1827 (22%) patients discontinued warfarin, whereas 6623 (78%) patients continued warfarin. Warfarin cessation was not associated with an increased risk of subsequent stroke (hazard ratio [HR] 0.99, 95% CI 0.82 to 1.21) or myocardial infarction (HR 0.94, 95% CI 0.74 to 1.20) but was associated with a lower risk of major hemorrhage (HR 0.69, 95% CI 0.54 to 0.88) and a higher risk of venous thromboembolism (HR 1.59, 95% CI 1.07 to 2.36). Adjustment for baseline demographics, stroke risk factors, other comorbidities, and characteristics of the trauma did not materially change these findings. On-treatment analyses yielded similar results.

Conclusions— Cessation of warfarin in elderly patients after major trauma was not associated with an increased risk of arterial thrombotic events but was associated with a significantly increased risk of venous thromboembolism.

Key Words: anticoagulants • epidemiology • stroke • follow-up studies