Is INR between 2.0 and 3.0 the optimal level for Chinese patients on warfarin therapy for moderate-intensity anticoagulation?
OBJECTIVE
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 (< or =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.
You
J H S
JH
School of Pharmacy, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong. joyceyou@cuhk.edu.hk
Chan
F W H
FW
Wong
R S M
RS
Cheng
G
G
D017677:Age Distribution; D000368:Aged; D000925:Anticoagulants / Q000627:therapeutic use*; D044466:Asian People; D015331:Cohort Studies; D006470:Hemorrhage / Q000097:blood* / Q000209:etiology; D006723:Hong Kong; D006801:Humans; D019934:International Normalized Ratio; D012189:Retrospective Studies; D013923:Thromboembolism / Q000097:blood* / Q000209:etiology; D014859:Warfarin / Q000627:therapeutic use*
D000925:Anticoagulants; D014859:Warfarin