title: Major bleeding risk in anticoagulated patients receiving concomitant antiplatelet therapy: a prospective study.
abstract: BACKGROUND
  Current literature suggesting a higher bleeding risk during combination therapy compared to oral anticoagulation alone is primarily based on retrospective studies or specific populations. We aimed to prospectively evaluate whether unselected medical patients on oral anticoagulation have an increased risk of bleeding when on concomitant antiplatelet therapy.
  
  
  METHODS
  We prospectively studied consecutive adult medical patients who were discharged on oral anticoagulants between 01/2008 and 03/2009 from a Swiss university hospital. The primary outcome was the time to a first major bleed on oral anticoagulation within 12 months, adjusted for age, international normalized ratio target, number of medications, and history of myocardial infarction and major bleeding.
  
  
  RESULTS
  Among the 515 included anticoagulated patients, the incidence rate of a first major bleed was 8.2 per 100 patient-years. Overall, 161 patients (31.3%) were on both anticoagulant and antiplatelet therapy, and these patients had a similar incidence rate of major bleeding compared to patients on oral anticoagulation alone (7.6 vs. 8.4 per 100 patient-years, P=0.81). In a multivariate analysis, the association of concomitant antiplatelet therapy with the risk of major bleeding was not statistically significant (hazard ratio 0.89, 95% confidence interval, 0.37-2.10).
  
  
  CONCLUSIONS
  The risk of bleeding in patients receiving oral anticoagulants combined with antiplatelet therapy was similar to patients receiving oral anticoagulants alone, suggesting that the incremental bleeding risk of combination therapy might not be clinically significant.
authors.affiliation: Division of General Internal Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02120-1613, USA. jdonze@partners.org
authors.forename: Jacques
authors.initials: J
authors.lastname: Donzé
authors.forename: Nicolas
authors.initials: N
authors.lastname: Rodondi
authors.forename: Gérard
authors.initials: G
authors.lastname: Waeber
authors.forename: Jacques
authors.initials: J
authors.lastname: Cornuz
authors.forename: Drahomir
authors.initials: D
authors.lastname: Aujesky
mesh_terms: D000328:Adult; D000368:Aged; D000925:Anticoagulants / Q000009:adverse effects*; D004359:Drug Therapy, Combination; D005260:Female; D006470:Hemorrhage / Q000139:chemically induced* / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010975:Platelet Aggregation Inhibitors / Q000009:adverse effects*; D011446:Prospective Studies; D012307:Risk Factors
chemical_list: D000925:Anticoagulants; D010975:Platelet Aggregation Inhibitors