title: Prognostic implications of warfarin cessation after major trauma: a population-based cohort analysis.
abstract: 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.
  
  
  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.
authors.affiliation: Division of Clinical Pharmacology, University of Toronto, Toronto, ON, Canada,
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Hackam
authors.forename: Alexander
authors.initials: A
authors.lastname: Kopp
authors.forename: Donald A
authors.initials: DA
authors.lastname: Redelmeier
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D000075202:Contraindications; D005260:Female; D005500:Follow-Up Studies; D006470:Hemorrhage / Q000139:chemically induced; D006801:Humans; D015994:Incidence; D008297:Male; D009203:Myocardial Infarction / Q000139:chemically induced; D011379:Prognosis; D012189:Retrospective Studies; D012306:Risk; D020521:Stroke / Q000139:chemically induced; D013927:Thrombosis / Q000139:chemically induced; D014859:Warfarin / Q000009:adverse effects*; D014947:Wounds and Injuries / Q000150:complications* / Q000453:epidemiology
chemical_list: D014859:Warfarin