Evidence-based On-call

Warfarin

Starting treatment
Indications
Dosing and monitoring
Complications
Follow-up

Dosing and monitoring

Use lower loading doses - they are more effective ^a

Why?

Patients given a loading dose of 5 mg compared with 10 mg are more likely to have an INR 2.0-3.0 for 2 consecutive days and never above 3.0 ^a

A 5 mg loading dose of warfarin leads to more successful anticoagulation than 10 mg

Patient	Treatment	Comparison	Outcome	CER	RRR (95% CI)	NNT (95% CI)
starting anticoagulation ^a	5 mg warfarin loading dose	10 mg warfarin loading dose	INR 2.0 to 3.0 on 2 consecutive days, and never > 3.0 at 5 days	24%	190% (27% to 540%)	2 (1 to 5)

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