Appropriate level and length of postthrombotic warfarin treatment: an evaluation of recent developments.

Current treatment and secondary prophylaxis of venous thromboembolism has two major drawbacks. During vitamin K antagonist therapy, patients need to be monitored closely to maintain efficacy and minimize the bleeding risk due to fluctuations of the prothrombin time (international normalized ratio, INR), and after cessation of therapy there is the problem of recurrent thrombosis, ie, the catch-up phenomenon. Recent studies indicate that for most patients, vitamin K antagonist therapy aimed at an INR of 2.0 to 3.0 is optimal. For patients with thrombosis due to a temporary risk factor, extending treatment beyond 3 months is not needed, whereas for other patients a minimal duration of 1 year can be advocated. For patients with cancer, it is beneficial to postpone therapy with vitamin K antagonists and prolong initial low-molecular-weight therapy for 3 to 6 months. New developments are aimed at further individualization of the duration of treatment and at the introduction of agents that are suitable for long-term treatment and do not require monitoring.