Venous thromboembolism - Warfarin may decrease the risk of recurrence in pts with calf DVT

Citation: Lagerstedt CL, Olsson CG, Fagher BO, Oqvist BW, Albrechtsson U. Need for long-term anticoagulant treatment in symptomatic calf-vein thrombosis. Lancet 1985;2:515-8

Three-part Question: In a patient with calf DVT does treatment with warfarin decrease the risk of recurrence?

Search Terms: "venous thromboembolism", "anticoagulation" in MEDLINE

Non-blinded randomised controlled trial with intention-to-treat. Pts admitted with calf DVT (see notes), excluded if popliteal extension, symptoms of PE, malignancy, conditions predisposing to recurrence of thrombosis, inability to co-operate or a hx of recurrent thrombosis meriting long-term anticoagulant treatment

Control group (N = 28; 28 analysed): heparin for at least 5 days, compression stockings

Experimental group (N = 24; 23 analysed): heparin for at least 5 days, compression stockings and warfarin adjusted to keep INR in range of 2.5-4.2

Comments:

1. Definition of calf DVT: "physical exam plus 99mTc-plasmin test, confirmed by phlebography" of calf DVT and no extension into the popliteal vein.
2. 1 pt in warfarin group had new thrombosis 15 days after warfarin discontinued and later diagnosed with lung cancer
3. 6 pts in control group had a hx of thrombosis and of these, 3 had a recurrence
4. perfusion scans done only at end of study, not at onset
5. 2 pts in warfarin group had abnormal perfusion scan at day 90 - 1 pt had pneumonia but does not mention dx of other patient
6. 3 pts in control group had abnormal scans - all had recurrent thrombosis
7. 2 pts in control group had major bleeds while on heparin (none in the warfarin group)

Appraised by: Straus ; 22 January 1998; Expiry date: Jan 1999

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