title: Factors determining the maintenance dose of warfarin in Chinese patients.
abstract: Chinese patients are reportedly more sensitive than Caucasians to the anticoagulant effect of warfarin. We examined warfarin dose requirements and their determinants in 151 Chinese out-patients on stable maintenance dose of warfarin with international normalized ratio of 2 to 2.5. Mean daily warfarin requirement was 3.3 +/- 1.4 mg, much lower than reported doses in Caucasian patients. The most important determinant was age (r = -0.43, p < 0.001), with progressively lower warfarin requirement with increasing age (p = 0.0001). There was a weaker association with body weight (r = 0.20, p = 0.01). Patients with chronic rheumatic heart disease tended to require a smaller dose than those with heart valve replacements (2.94 +/- 1.24 vs. 3.69 +/- 1.42 mg, p < 0.01). We confirm that Chinese patients require a smaller dose of warfarin for the same degree of anticoagulation. Age is the most important factor affecting dose requirement, although body weight and underlying disease also play a role.
authors.affiliation: Department of Medicine, Chinese University of Hong Kong.
authors.forename: H C
authors.initials: HC
authors.lastname: Yu
authors.forename: T Y
authors.initials: TY
authors.lastname: Chan
authors.forename: J A
authors.initials: JA
authors.lastname: Critchley
authors.forename: K S
authors.initials: KS
authors.lastname: Woo
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000008:administration & dosage* / Q000627:therapeutic use; D044466:Asian People; D001778:Blood Coagulation Disorders / Q000208:ethnology* / Q000517:prevention & control; D001835:Body Weight; D002318:Cardiovascular Diseases / Q000188:drug therapy / Q000208:ethnology*; D004334:Drug Administration Schedule; D005260:Female; D006350:Heart Valve Prosthesis; D006723:Hong Kong; D006801:Humans; D008297:Male; D008875:Middle Aged; D012214:Rheumatic Heart Disease / Q000208:ethnology; D012737:Sex Factors; D013924:Thrombophlebitis / Q000208:ethnology; D014859:Warfarin / Q000008:administration & dosage* / Q000627:therapeutic use
chemical_list: D000925:Anticoagulants; D014859:Warfarin