Warfarin Dosing and Time Required to Reach Therapeutic International Normalized Ratio in Patients with Hypercoagulable Conditions.
OBJECTIVE
The purpose of this study was to analyze the difference in duration of anticoagulation and dose of warfarin required to reach a therapeutic international normalized ratio [(INR) of 2 to 3] in patients with hypercoagulable conditions as compared to controls. To our knowledge, this study is the first in the literature to delineate such a difference.


METHODS
A retrospective chart review was performed in a tertiary care hospital. The total study population was 622. Cases (n=125) were patients with a diagnosis of a hypercoagulable syndrome who developed venous thromboembolism. Controls (n=497) were patients with a diagnosis of venous thromboembolism in the absence of a hypercoagulable syndrome and were matched for age, sex, and race.


RESULTS
The total dose of warfarin required to reach therapeutic INR in cases was higher (50.7±17.6 mg) as compared to controls (41.2±17.7 mg). The total number of days required to reach therapeutic INR in cases was 8.9±3.5 days as compared to controls (6.8±2.9 days). Both of these differences were statistically significant (p<0.001).


CONCLUSIONS
Patients with hypercoagulable conditions require approximately 10 mg of additional total warfarin dose and also require, on average, 2 extra days to reach therapeutic INR as compared to controls.
Pushpinderdeep
P
Kahlon
Wayne State University, Henry Ford Health System, Clinic of Internal Medicine, Detroit, USA, Phone: +1-313-482-8768, E-mail: shahzaib.nabi@ucdenver.edu.
Shahzaib
S
Nabi
Adeel
A
Arshad
Absia
A
Jabbar
Ali
A
Haythem
D000328:Adult; D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage*; D001777:Blood Coagulation; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D019934:International Normalized Ratio; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012189:Retrospective Studies; D019851:Thrombophilia / Q000097:blood* / Q000175:diagnosis / Q000188:drug therapy* / Q000209:etiology; D013997:Time Factors; D020246:Venous Thrombosis / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy / Q000209:etiology; D014859:Warfarin / Q000008:administration & dosage*
D000925:Anticoagulants; D014859:Warfarin