OBJECTIVE: To determine the incidence of major hemorrhage among outpatients started on warfarin therapy after the recommendation in
1986 for reduced-intensity anticoagulation therapy was made, and to identify baseline patient characteristics that predict
those patients who will have a major hemorrhage.
DESIGN: Retrospective cohort study.
SETTING: A university-affiliated Veterans Affairs Medical Center.
PATIENTS: Five hundred seventy-nine patients who were discharged from the hospital after being started on varfarin therapy.
MEASUREMENTS AND MAIN RESULTS: The primary outcome variable was major hemorrhage. In our cohort of 579 patients, there were 40 first-time major hemorrhages
with only one fatal bleed. The cumulative incidence was 7% at 1 year. The average monthly incidence of major hemorrhage was
0.82% during the first 3 months of treatment and decreased to 0.36% thereafter. Three independent predictors of major hemorrhage
were identified: a history of alcohol abuse, chronic renal insufficiency, and a previous gastrointestinal bleed. Age, comorbidities,
medications known to influence prothrombin levels, and baseline laboratory values were not associated with major hemorrhage.
CONCLUSIONS: The incidence of major hemorrhage in this population of outpatients treated with warfarin was lower than previous estimates
of major hemorrhage measured before the recommendation for reduced-intensity anticoagulation therapy was made, but still higher
than estimates reported from clinical trials. Alcohol abuse, chronic renal insufficiency, and a previous gastrointestinal
bleed were associated with increased risk of major hemorrhage.
Key words major hemorrhage - warfarin - alcohol abuse - chronic renal insufficiency - gastrointestinal hemorrhage