title: Clinical outcome in Japanese elderly patients with non-valvular atrial fibrillation taking warfarin: a single-center observational study.
abstract: BACKGROUND
  Although a lower target prothrombin time-international normalized ratio (PT-INR) with warfarin therapy is recommended in Japan for atrial fibrillation (AF) patients ≥70 years of age, few studies have provided supporting data. The current study aimed to evaluate the clinical outcome in elderly Japanese patients with non-valvular AF who were taking warfarin.
  
  
  METHODS
  We conducted a cohort study of 845 consecutive non-valvular AF patients ≥70 years of age who were taking warfarin (median age, 74 years; 30.5% women) with a median follow-up period of 27 months (4-69 months). Of these patients, 29.7% had a history of stoke/transient ischemic attack (TIA), and 73.1% of the patients had a CHADS(2) score ≥2. The occurrence of thromboembolic events, including ischemic stroke, TIA and other systemic embolisms, and major bleeding events were validated through a review of medical records.
  
  
  RESULTS
  The incidence of thromboembolic and major bleeding events were 3.8 and 2.1% per year, respectively. A higher incidence of both events was observed in patients with a CHADS(2) score ≥3. The multivariate analysis showed that prior stroke/TIA (odds ratio 1.7, 95% CI 1.0-2.7) and diabetes (odds ratio 1.7, 95% CI 1.0-2.8) were independent risks of thromoembolic events. A HAS-BLED score ≥3 represented a risk for major bleeding (hazard ratio 2.8, 95% CI 1.7-4.6). A PT-INR of 1.5-2.5 indicated a low incidence of thromboembolic and major bleeding events in patients with a CHADS(2) score ≥2.
  
  
  CONCLUSIONS
  Our results demonstrate that a target PT-INR of 2.0 and a range of 1.5-2.5 may be safe for elderly Japanese patients with non-valvular AF.
authors.affiliation: The Center for Clinical Research, Tokyo Women's Medical University Hospital, Tokyo, Japan.
authors.forename: Miyoko
authors.initials: M
authors.lastname: Naganuma
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Shiga
authors.forename: Kumi
authors.initials: K
authors.lastname: Sato
authors.forename: Kagari
authors.initials: K
authors.lastname: Murasaki
authors.forename: Masayuki
authors.initials: M
authors.lastname: Hashiguchi
authors.forename: Mayumi
authors.initials: M
authors.lastname: Mochizuki
authors.forename: Nobuhisa
authors.initials: N
authors.lastname: Hagiwara
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000009:adverse effects / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000150:complications / Q000188:drug therapy*; D015331:Cohort Studies; D005260:Female; D006470:Hemorrhage / Q000209:etiology; D006801:Humans; D019934:International Normalized Ratio; D002546:Ischemic Attack, Transient / Q000150:complications; D008297:Male; D011517:Prothrombin Time; D020521:Stroke / Q000150:complications; D013923:Thromboembolism / Q000209:etiology; D016896:Treatment Outcome; D014859:Warfarin / Q000009:adverse effects / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D014859:Warfarin