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Is INR between 2.0 and 3.0 the optimal level for Chinese patients on warfarin therapy for moderate‐intensity anticoagulation?
Author(s) -
You J. H. S.,
Chan F. W. H.,
Wong R. S. M.,
Cheng G.
Publication year - 2005
Publication title -
british journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.216
H-Index - 146
eISSN - 1365-2125
pISSN - 0306-5251
DOI - 10.1111/j.1365-2125.2005.02361.x
Subject(s) - medicine , warfarin , incidence (geometry) , ambulatory , retrospective cohort study , cohort , cohort study , pediatrics , emergency medicine , atrial fibrillation , physics , optics
Aim To examine the optimal range of International Normalized Ratio (INR) for Chinese patients receiving warfarin for moderate‐intensity anticoagulation. Methods This was a retrospective cohort study conducted at the ambulatory setting of a 1400‐bed public teaching hospital in Hong Kong. The INR measurements and occurrence of serious or life‐threatening haemorrhagic and thromboembolic events among patients newly started on warfarin from 1 January 1999 to 30 June 2001 for indications with target INR 2–3 were analysed. The INR‐specific incidence of bleeding and thromboembolism were calculated. Results A total of 491 patients were included, contributing to 453 patient‐years of observation period. Forty‐seven of the 491 patients experienced 25 haemorrhagic events (5.5 per 100 patient‐years) and 27 thromboembolic events (6.0 per 100 patient‐years). The percentage of patient‐time spent within therapeutic INR range (2–3), INR <2 and INR >3 were 50, 44 and 6%, respectively. The incidence of either haemorrhagic or thromboembolic events was lowest (≤4 events per 100 patient‐years) at INR values between 1.8 and 2.4. Conclusions An INR of 1.8–2.4 appeared to be associated with the lowest incidence rate of major bleeding or thromboembolic events in a cohort of Hong Kong Chinese patients receiving warfarin therapy for moderate‐intensity anticoagulation.