Prevention of Recurrent Venous Thromboembolism
N Engl J Med Apr 10 2003;348(15) :1425-1434
PREVENT (Warfarin) Trial
Warfarin (target INR, 1.5-2.0)
(n = 255)
Placebo
(n = 253)
Endpoints (mean follow-up 2.1 years):
Primary – 1) recurrent venous thromboembolism and 2) composite of recurrent venous thromboembolism, major hemorrhage, or death
PREVENT Trial
N Engl J Med Apr 10 2003;348(15) :1425-1434
Open-label therapy for 28 days
To determine if warfarin dose could be titrated to an INR of 1.5 to 2.0 without exceeding 10 mg per day
To see if patients could maintain a compliance of 85%
508 patients with documented idiopathic venous thromboembolism, >3 uninterrupted months of oral anticoagulation therapy with full-dose warfarin
Age >30 years
PREVENT Trial: Composite Endpoint
Placebo
N Engl J Med Apr 10 2003;348(15) :1425-1434
* Composite of recurrent
thromboembolism, major bleed and death
Composite
Endpoint*
HR = 0.52, p=0.01
Trial discontinued early by the DSMB, due to a large, significant benefit with low-intensity warfarin therapy and the absence of any substantial evidence of any significant untoward side effects
Warfarin
PREVENT Trial
N Engl J Med Apr 10 2003;348(15) :1425-1434
Warfarin
Placebo
Recurrent Venous
Thromboembolism
HR = 0.36, p<0.001
Warfarin
Placebo
All-Cause
Mortality
HR = 0.50, p=0.26
PREVENT: Conclusions
Among patients with idiopathic venous thromboembolism who had received full-dose anticoagulation therapy for six months, treatment with low-intensity warfarin (target INR, 1.5-2.0) was associated with a reduction in recurrent venous thromboembolism and in the composite of recurrent venous thromboembolism, major hemorrhage, or death during follow-up
No significant excess major bleeding occurred in the warfarin arm
First randomized trial to examine the use of low-intensity warfarin therapy, rather than full-dose therapy in this population