title: Net clinical benefit of adding aspirin to warfarin in patients with atrial fibrillation: Insights from the J-RHYTHM Registry.
abstract: BACKGROUND
  Concomitant use of vitamin K antagonist (VKA) and aspirin (ASA) is becoming increasingly prevalent among atrial fibrillation (AF) patients. We quantified the net clinical benefit of adding ASA to a VKA using nationwide prospective AF registry data.
  
  
  METHODS
  We studied 6074 patients (VKA monotherapy: 83% and VKA+ASA: 17%) between January 2009 and July 2009, and followed them for a mean follow-up period of 2years. The risk of strokes and bleeding was calculated by the CHA2DS2-VASc and HAS-BLED scores. The net clinical benefit was defined as the annual rate of ischemic strokes and systemic emboli prevented by VKAs minus intracranial hemorrhages attributable to the VKA+ASA, multiplied by an impact weight of 1.5.
  
  
  RESULTS
  Patients on a VKA+ASA were older with more medical comorbidities than those on VKA alone. Using VKA monotherapy as a reference, higher major bleeding rates and all-cause death were evident in those on VKA+ASA. The net clinical benefit of VKA+ASA for the overall cohort was -0.1%/year (95% confidence interval, -0.74% to 0.46%). There was a trend toward a negative net clinical benefit from VKA+ASA in patients with a CHA2DS2-VASc≥2 and HAS-BLED≤2 (-1.17%/year). The VKA+ASA yielded a positive net clinical benefit in patients with a CHA2DS2-VASc≥2 and HAS-BLED≥3 (1.16%/year). The result patterns were relatively constant using impact weight of 1.0 and 2.0.
  
  
  CONCLUSIONS
  Our estimates of the net clinical benefit can provide a useful anchoring point for adding ASA to VKA in patients with AF.
authors.affiliation: Department of Cardiology, Fujita Health University School of Medicine, Toyoake, Japan. Electronic address: enwatan@fujita-hu.ac.jp.
authors.forename: Eiichi
authors.initials: E
authors.lastname: Watanabe
authors.affiliation: Department of Cardiology, Fujita Health University School of Medicine, Toyoake, Japan.
authors.forename: Mayumi
authors.initials: M
authors.lastname: Yamamoto
authors.affiliation: Nagoya University, Nagoya, Japan.
authors.forename: Itsuo
authors.initials: I
authors.lastname: Kodama
authors.affiliation: Second Department of Internal Medicine, Toyama University Hospital, Toyama, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Inoue
authors.affiliation: Department of Cardiology, Nippon Medical School, Tama-Nagayama Hospital, Tokyo, Japan.
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Atarashi
authors.affiliation: Department of Cardiology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Okumura
authors.affiliation: Department of Cardiovascular Medicine, The Cardiovascular Institute, Tokyo, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yamashita
authors.affiliation: University of Birmingham Institute of Cardiovascular Sciences, City Hospital, Birmingham, England, UK.
authors.forename: Gregory Y H
authors.initials: GY
authors.lastname: Lip
authors.affiliation: Department of Cardiology, Nippon Medical School, Tama-Nagayama Hospital, Tokyo, Japan.
authors.forename: Eitaro
authors.initials: E
authors.lastname: Kodani
authors.affiliation: Department of Advanced Cardiovascular Therapeutics, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Okuyama
authors.affiliation: Department of Health Sciences, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Chishaki
authors.affiliation: Division of Bioengineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Kiyono
authors.affiliation: Division of Biostatistics and Clinical Epidemiology, University of Toyama, Toyama, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Origasa
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000627:therapeutic use*; D001241:Aspirin / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000188:drug therapy*; D005260:Female; D006801:Humans; D020300:Intracranial Hemorrhages / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D018570:Risk Assessment; D020521:Stroke / Q000453:epidemiology*; D016896:Treatment Outcome; D014859:Warfarin / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D014859:Warfarin; D001241:Aspirin
keywords: Arrhythmia; Aspirin; Stroke and hemorrhage; Warfarin