Duration of Anticoagulation Following Venous Thromboembolism

Abstract

Patients who receive extended anticoagulation are protected from recurrent VTE while receiving long-term therapy. The clinical benefit is maintained after anticoagulation is discontinued, but the magnitude of the benefit is less pronounced.

In Search of Safe and Effective Oral Anticoagulation

“…Among 3,407 high-risk patients with AF over a mean length of 17 months of follow-up, ximelagatran had an incidence of 40 strokes (1.6% per year) or embolic events compared with 56 strokes among warfarin patients (2.3% per year); absolute risk reduction 0.7% (95% CI, -0.1 to 1.4); P=0. 10. 17 More warfarin patients (86%) completed the study than did ximelagatran patients (82%), and the total mortality was approximately the same in both groups (4.6%).…”

“…In a meta-analysis of RCTs with results published from 1969 through 2004 in PubMed, EMBase Pharmacology, the Cochrane database, clinical trial Web sites, and a hand search of reference lists, Ost et al determined that the incidence of recurrent VTE with long-term (>6 months) anticoagulation therapy in patients with a first episode of VTE (or therapy that involved anticoagulation with one or more agents) was 0.020 events per person-year (i.e., 1 in 50) compared with a rate 6 times higher (0.126 events per person-year) for shorter therapy (P <0.001). 10 The authors concluded that the optimum length of warfarin therapy was not clear, but 6 or more months of treatment appeared to be beneficial, particularly for patients at higher risk, even though the duration of anticoagulation beyond 6 months results in a relatively modest incremental risk reduction. What is more, this study pointed out that (a) the number needed to treat to prevent 1 VTE event with long-term anticoagulation would be approximately 50 (95% CI, 25-1,000), (b) the effect size with lifelong therapy is much larger since the number needed to treat to prevent 1 VTE event with lifelong anticoagulation would be approximately 9 (95% CI, 7-14), but (c) the relative amount of harm that is associated with each adverse outcome is important to consider since, for example, the damage from an intracranial hemorrhage can be much more serious than a VTE of the lower extremity.…”

Diagnosis and Treatment of Lower Extremity Deep Vein Thrombosis: Korean Practice Guidelines

“…Four systematic reviews have addressed the duration of anticoagulation with VKA, principally warfarin, after an episode of proximal lower extremity DVT [126][127][128][129]. A meta-analysis of 15 studies revealed that shorter-term VKA treatment (median, 1.75 months) results in more recurrences than longer-term treatment (median, 6 months) [126].…”

“…A meta-analysis of 15 studies revealed that shorter-term VKA treatment (median, 1.75 months) results in more recurrences than longer-term treatment (median, 6 months) [126]. In two studies comparing 6 and 3 months of treatment with VKA in patients with VTE which was unprovoked or provoked by a reversible risk factor, there was no difference in the risk of recurrence [130,131].…”

Diagnosis and treatment of deep-vein thrombosis

“…However, the risk of recurrent venous thromboembolism in the first year after stopping anticoagulation therapy is about 10%, regardless of when the therapy is stopped after 6 months. 45 When considering prolonging anticoagulation therapy after 6 months, the risks of bleeding with long-term anticoagulation therapy must be individualized and weighed against the potential benefits of preventing recurrence of thrombosis. In addition to the thrombophilic defects described previ- ously, 2 factors have been shown to increase the risk of recurrence after stopping anticoagulation therapy.…”