Treatment with vitamin K antagonists: frequency of indications and appropriateness of continuation

To prevent venous and arterial thrombosis vitamin K antagonists (VKA) are the treatment of choice for many indications. It is important to balance the benefits and the potential hazards of this treatment. An effective way to prevent unnecessary bleeding during VKA treatment is to stop treatment when the indication is no longer present. In this study, we analyze the distribution of indications in a randomly selected group of 250 patients starting VKA treatment at the Amsterdam Thrombosis Service. The proportion of patients still treated after one year of follow-up was also investigated. The distribution of the indications among patients starting VKA therapy was approximately 50% for venous thromboembolism treatment and prophylaxis, and approximately 50% for prophylaxis of arterial thrombosis. After one year of follow-up, 164 (65.6%) of the 250 patients had stopped VKA therapy. Reasons for stopping included: no indication for continuing VKA treatment, e.g. end of treatment, prophylaxis or restoration of sinus rhythm (137 patients); death (17) and other reasons (10). Six (2.4%; 95% CI: 0.9-5.1%) patients had a questionable indication for long-term treatment, and 9 (3.6%, 95% CI: 1.6-6.7%) patients had no clear indication for continued VKA treatment. We conclude that in the setting of the Amsterdam Thrombosis Service, only a small proportion of patients is treated with long-term VKA therapy without a valid indication after 1 year.