title: Factors associated with warfarin discontinuation, including bleeding patterns, in atrial fibrillation patients.
abstract: OBJECTIVE
  To determine risk factors for both warfarin discontinuation and bleeding in patients with atrial fibrillation (AF).
  
  
  METHODS
  Data from the MarketScan database (January 2005-June 2008) were retrospectively analyzed for patients ≥18 years old who used warfarin continuously (≥2 prescriptions for 6 months) subsequent to an AF diagnosis. Patients were followed until one of the following endpoints occurred: warfarin discontinuation or end of the 30 month study period (whichever happened first). Recent bleeding was defined as occurring within 90 days before discontinuation. Drug interactions related to bleeding were defined as occurring within 120 days prior to bleeding.
  
  
  RESULTS
  The study included 7971 eligible patients (mean age 67.8 years; 41.2% female). During follow-up, 51.7% of patients discontinued warfarin (P < .001). More patients with recent bleeding (61.8%) discontinued warfarin compared to patients without recent bleeding (51.3%). After adjustment, patients with recent bleeding were 35% more likely to discontinue warfarin compared to those without recent bleeding (relative risk = 1.35; CI: 1.16-1.58). Age >85 years and a history of ≥1 hospitalizations/emergency room visits were associated with an increased likelihood of discontinuation (P < .001). Female gender, daily dosage >5 mg, concomitant use of gastroprotective agents, and CHADS2 scores ≥1 were associated with a decreased likelihood of discontinuation (P < .05).
  
  
  CONCLUSIONS
  Risk factors for warfarin discontinuation include older age, recent bleeding, and a high number of concomitant medications. Risk factors associated with bleeding events are older age, use of a warfarin-potentiating medication, previous bleeding, and higher CHADS2 scores.
authors.affiliation: Chung-Ang University College of Pharmacy, Seoul, South Korea. dongsuh75@gmail.com
authors.forename: Dong-Churl
authors.initials: DC
authors.lastname: Suh
authors.forename: Jiyoon C
authors.initials: JC
authors.lastname: Choi
authors.forename: Jeff
authors.initials: J
authors.lastname: Schein
authors.forename: Suhyun
authors.initials: S
authors.lastname: Kim
authors.forename: Winnie W
authors.initials: WW
authors.lastname: Nelson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000009:adverse effects / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000188:drug therapy; D005260:Female; D006470:Hemorrhage / Q000139:chemically induced*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D014859:Warfarin / Q000009:adverse effects / Q000627:therapeutic use*; D055815:Young Adult; D016903:Drug Monitoring
chemical_list: D000925:Anticoagulants; D014859:Warfarin