title: Warfarin anticoagulation intensity in Japanese nonvalvular atrial fibrillation patients: a J-RHYTHM Registry analysis.
abstract: BACKGROUND
  To maximize protection against stroke with minimal bleeding, warfarin therapy in nonvalvular atrial fibrillation (NVAF) requires tight control within a narrow therapeutic range, which might depend on racial variations.
  
  
  METHODS
  The J-RHYTHM Registry followed 6404 NVAF patients treated with warfarin for 2 years. Using international normalized ratios (INRs) at or closest to the embolic and intracranial hemorrhagic (ICH) events, we determined odds ratios for ischemic stroke/systemic embolism (SE) and ICH according to any given INR with a reference INR range including 2.0.
  
  
  RESULTS
  Ischemic stroke and SE occurred in 97 of the patients and ICH occurred in 49. The estimated INR-risk relationships showed characteristics of Japanese NVAF patients. Compared to INR-risk relationships reported for Westerners, those observed in Japanese patients were virtually identical for ischemic stroke/SE and shifted leftward by approximately 0.5 INR for ICH.
  
  
  CONCLUSIONS
  This is the largest Japanese study providing fundamental data necessary to establish optimal anticoagulation intensities. Japanese NVAF patients may require narrower therapeutic ranges than Westerners.
authors.affiliation: The Cardiovascular Institute, Tokyo, Japan. Electronic address: yamt-tky@umin.ac.jp.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yamashita
authors.affiliation: Second Department of Internal Medicine, University of Toyama School of Medicine, Toyama, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Inoue
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 Cardiology, Nippon Medical School Tama-Nagayama Hospital, Tama, Japan.
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Atarashi
authors.affiliation: Division of Biostatistics and Clinical Epidemiology, University of Toyama School of Medicine, Toyama, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Origasa
mesh_terms: D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage* / Q000009:adverse effects; D001281:Atrial Fibrillation / Q000150:complications* / Q000208:ethnology; D004617:Embolism / Q000139:chemically induced / Q000517:prevention & control; D005260:Female; D006470:Hemorrhage / Q000139:chemically induced / Q000517:prevention & control; D006801:Humans; D019934:International Normalized Ratio; D020300:Intracranial Hemorrhages / Q000139:chemically induced / Q000517:prevention & control; D007564:Japan / Q000208:ethnology; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012042:Registries; D012306:Risk; D020521:Stroke / Q000209:etiology / Q000517:prevention & control*; D014859:Warfarin / Q000008:administration & dosage* / Q000009:adverse effects
chemical_list: D000925:Anticoagulants; D014859:Warfarin
keywords: Atrial fibrillation; INR; Intracranial hemorrhage; Stroke; Warfarin