Evidence-based On-call

Warfarin

Starting treatment
Indications
Dosing and monitoring
Complications
Follow-up

Dosing and monitoring

Start warfarin as soon as possible ^a

and monitor its effect using INR. ^a

Why?

Starting warfarin within 48 hours of heparin reduces hospital stays (by around 4 days) and occurrence of infusion phlebitis compared with starting warfarin after 96 hours. ^a
The effect on major bleeds or recurrent venous thromboembolism is unclear. ^a

Starting warfarin within 48 hours reduces infusion phlebitis

Patient	Treatment	Comparison	Outcome	CER	RRR (95% CI)	NNT (95% CI)
thromboembolism ^a	warfarin started within 48 hours	warfarin started after 96 hours	infusion phlebitis at at discharge	18%	91% (33% to 99%)	6 (4 to 17)

Expiry date: May 2003
Levels of Evidence used in grading these guides

With thanks to Drs. David Keeling, John Reynolds, David Sackett, Sharon Straus and Alan Townsend
for use of their anticoagulation guide on which this one is based.

Author	CM Ball
Reviewer	A Gallus
CAT Writer	CM Ball