Deep vein thrombosis: calf: three months of anticoagulation reduced recurrences.

Clinical bottom line (level 1b)

  1. Patients with calf DVT who were given three months of warfarin after heparin treatment, had fewer recurrent episodes of DVT or PE than those given heparin alone for five days (NNT = 4 at 12 months) .
Lagerstedt et al: Lancet 1985; 2: 515-518
Expires March 2003

The study

Unblinded concealed randomised trial with intention-to-treat
Setting: acute hospital, Sweden

51 patients (aged mean 62 years, 57% male) admitted with calf deep vein thrombosis, diagnosed by 'physical exam plus 99mTc-plasmin test', confirmed by venogram as a calf DVT with no extension into popliteal vein

Excluded if
  • popliteal extension
  • symptoms of pulmonary embolism
  • malignancy
  • conditions predisposing to recurrence of thrombosis
  • inability to co-operate
  • history of recurrent thrombosis meriting long-term anticoagulation


    • Control Group: (n = 28, 28 analysed): heparin 500-600 units/kg/day for at least five days; compression stockings were also worn
    Experimental Group: (n = 24, 23 analysed): heparin for at least five days; compression stockings and warfarin as soon as DVT confirmed on venogram, for three months- adjusted to keep INR in range of 2.5 to 4.2

    100% followed for 12 months
    Outcome notes:
    • venous thromboembolism recurrence : diagnosed by venography

    The evidence

    Outcome Time to outcome CEREERRRR
    (95% CI)    		ARR
    (95% CI)    		NNT
    (95% CI)
    venous thromboembolism recurrence 90 days 6
    (29%)    		 0
    (0%)    		 100%
    (% to %)    		 28.6%
    (11.8% to 45.3%)    		 4
    (2 to 8)
    VTE recurrence 12 months 9
    (32%)    		 1
    (4%)    		 87%
    (5% to 98%)    		 28.0%
    (8.92% to 47.0%)    		 4
    (2 to 11)

  • Six patients in the control group had a history of thrombosis- three of these had a recurrence.

    • Citation

    1. Lagerstedt CI, Olsson C-G, Fagher BO, et al: Need for long-term anticoagulant treatment in symptomatic calf-vein thrombosis. Lancet 1985; 2: 515-518
    Contributor: Sharon Straus, Chris Ball and Clare Wotton, May 2000
    Reviewer:

    Clinical Question.
    Patient calf DVT
    Intervention or Exposure heparin plus warfarin
    Comparison heparin alone
    Outcome VTE recurrence