Low intensity warfarin anticoagulation is safe and effective as a long-term venous thromboembolism prevention strategy

Longitudinal studies indicate a high rate of recurrence of venous thromboembolism after an episode of deep venous thrombosis or pulmonary embolism. Extended anticoagulant therapy will decrease the recurrence rate, but there is controversy as to the optimal intensity of therapy that will be effective, yet safe. The PREVENT trial addresses the question of whether long-term low intensity therapy (INR 1.5-2.0) will effectively prevent recurrence compared to placebo treatment, yet be safe without a significant increase in major bleeding. The results of this trial show a significant reduction in recurrent venous thromboembolism with a major bleeding rate that is no different than the placebo arm of the study (0.9 vs 0.4 per 100 patient years; p = 0.25). Although the ELATE trial showed greater effectiveness with no increase in bleeding in the standard intensity arm vs the low intensity arm, the question remains whether such safety can be obtained in the real world management of oral anticoagulation.