Abstract 11270: Incidence of Bleeding Events in Patients on Warfarin, Aspirin and/or Clopidogrel in an Anticoagulation Clinic of a Tertiary Medical Center
Background: Warfarin's narrow therapeutic window poses a significant dilemma in clinical practice. There is limited data about the risks of combination therapy with warfarin, aspirin and/or clopidogrel even though this regimen is being more commonly used in the care of patients with cardiovascular disease.
Objectives: To evaluate the risk of all bleeding events in a clinic population and to investigate the rate of major bleeding events compared to minor bleeding in different treatment regimens.
Methods: In a retrospective cohort study design, we analyzed 119 reported bleeding events among 5,992 patients who were being followed at an anticoagulation clinic in a tertiary medical center from August 2003 to June 2009. Complete data were available for 108 events. Major bleeding events (MBE) were defined as those requiring blood transfusion and/or intracranial hemorrhage. Three groups were defined. Group 1(N=74) includes patients on warfarin therapy only. Group 2 (N=26) have those on warfarin and aspirin only. Group 3 (N=8) consists of patients on triple therapy (warfarin, aspirin and clopidogrel). The risk of all bleeding events in the total population was calculated. Odds ratios comparing major bleeding to minor bleeding were calculated. Multivariate analysis was done controlling for potential confounders.
Results: The mean (SD) age was 71.3 (13.8) years, 44.4% were male, 87.0% had hypertension, 36.4% had diabetes mellitus and 53.7% had coronary artery disease. The annual risk of all bleeding events (minor and major) is 0.33%. The ratio of developing a major bleeding event compared to a minor one was not significantly different for group 2 (80.8%) [OR 1.253; 95% CI; 0.411, 3.822] or group 3 (75%) (OR 0.964; 95% CI: 0.549, 1.692) when compared to group 1 (77%). The odds ratios remain unsignificant after controlling for age, sex, hypertension, diabetes mellitus and INR levels.
Conclusions: The risk of bleeding in a highly-coordinated tertiary care anticoagulation management clinic is much lower than that reported in the literature, suggesting that the type of anticoagulation clinic may impact the risk of bleeding. Also, compared to developing minor bleeding, patients on dual or triple therapy are not at higher risk of experiencing significant major bleeding events.
- © 2010 by American Heart Association, Inc.