Evaluation of very low-dose subcutaneous vitamin K during postoperative warfarin therapy.
OBJECTIVE
To determine the effect of very low-dose subcutaneous vitamin K (SCVK) compared with withholding warfarin for above-target international normalized ratio (INR) values after joint surgery.


METHODS
Historical controlled study.


METHODS
University hospital.


METHODS
One hundred thirty-nine patients beginning warfarin after total joint surgery.


METHODS
For a high INR, warfarin was either withheld or SCVK 100, 300, or 400 microg was administered, depending on INR value.


RESULTS
The primary outcome was change in INR from the day of intervention (day 1) to the next day (day 2). Adjusting for day 1 INR, the mean day 2 INR was 2.10 (95% confidence interval [CI] 1.86-2.33) after SCVK, compared with 2.73 (95% CI 2.50-2.96) in controls. This corresponded to declines of -0.72 and -0.08, respectively (p=0.001).


CONCLUSIONS
In orthopedic patients starting warfarin therapy, very low-dose SCVK was more effective than withholding warfarin in reducing high INRs. Investigations in other populations and assessment of the effect of low-dose SCVK on postoperative bleeding are indicated.
Department of Pharmacotherapy, Fletcher Allen Health Care, Burlington, Vermont, USA.
C J
CJ
Possidente
J G
JG
Howe
M
M
Cushman
D000368:Aged; D000925:Anticoagulants / Q000009:adverse effects*; D005260:Female; D006490:Hemostatics / Q000008:administration & dosage / Q000627:therapeutic use*; D006801:Humans; D007279:Injections, Subcutaneous; D019934:International Normalized Ratio; D007596:Joints / Q000601:surgery; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures; D011182:Postoperative Care; D011446:Prospective Studies; D011517:Prothrombin Time; D016896:Treatment Outcome; D014812:Vitamin K / Q000008:administration & dosage / Q000627:therapeutic use*; D014859:Warfarin / Q000627:therapeutic use*
D000925:Anticoagulants; D006490:Hemostatics; D014812:Vitamin K; D014859:Warfarin