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Evidence summaries

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

Long-term anticoagulant therapy after first episode of venous thromboembolism reduces the risk of recurrence without increasing the incidence of bleeding events. Level of evidence: "A"

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.

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    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]

Primary/Secondary Keywords