Long Versus Short Duration of Anticoagulant Therapy after a First Episode of Venous Thromboembolism

A systematic review 1 including 7 studies with a total of 2 304 subjects was abstracted in DARE. 1 156 patients received short-term therapy (3 to 12 weeks) and 1 148 received long-term therapy (6 weeks to 2 years).

Thrombotic recurrence at 12 months (7 RCTs): Recurrence rates were greater in those receiving short-term compared to long-term therapy (11.1% versus 6.4%). Long-term treatment significantly reduced the incidence of recurrence compared to short duration, regardless of the statistical method used; RR 0.60 (95% CI 0.45 to 0.79). No significant heterogeneity was found.

Limiting analysis to the three most recent and adequately designed trials also showed a significant reduction in patients receiving long-term compared to short-term therapy; RR 0.45 (95% CI 0.32 to 0.63). No significant heterogeneity was found.

Major bleeding (3 RCTs): Major bleeding was more common in those receiving long-term compared to short-term therapy (weighted mean of major bleeding was 1.1 versus 0.7%). Duration of anticoagulant therapy (short- versus long-term) had no statistically-significant effect on the incidence of major bleeding on any statistical method used; RR 1.43 (95% CI 0.51 to 4.01).

Influence of risk factors: Permanent risk factors and idiopathic VTE (4 RCTs): recurrence rates were greater in the short compared to the long duration of therapy groups (13.8% versus 6.7%). Long-term treatment significantly reduced the incidence of recurrence compared to short-term treatment; RR 0.48 (95% CI 0.34 to 0.68).

Temporary risk factors and idiopathic VTE (4 RCTs): recurrence rates were less than in patients with permanent risk factors, and were greater with short-term compared to long-term therapy (5.3% versus 1.4%).

Conclusions:After a first episode of VTE, a longer treatment regimen allows a significant reduction in the incidence of recurrences without increasing the incidence of bleeding events. The optimal duration has yet to be determined.

The following decision support rules contain links to this evidence summary:

• Duration of anticoagulation in deep venous thrombosis http://www.ebmeds.org/ebmeds/ebmeds_home.asp?mode=scripts&submode=view&id=scr00532&country=UK

References

• Pinede L, Duhaut P, Cucherat M, Ninet J, Pasquier J, Boissel JP. Comparison of long versus short duration of anticoagulant therapy after a first episode of venous thromboembolism: a meta-analysis of randomized, controlled trials. J Intern Med 2000 May;247(5):553-62. [PubMed] [DARE]