According to results from the PADIS-DVT trial (ClinicalTrials.gov Identifier: NCT00740493) published in Haematologica, continuing warfarin therapy for 18 months following an initial 6-month course after a first unprovoked proximal deep vein thrombosis reduced the composite outcome of recurrent venous thrombosis and major bleeding compared with placebo. However, this benefit did not persist after anticoagulation therapy was stopped.

The study was a multicenter, randomized, double blind trial. Patients with a first episode of unprovoked proximal deep vein thrombosis were treated with an initial 6-month course of oral anticoagulant therapy and then given either placebo (54 patients) or an additional 18 months of treatment with warfarin (50 patients).

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The primary outcome was a composite of the 2 main complications of venous thrombosis management, recurrent venous thromboembolism or major bleeding, at 18 months. The secondary outcomes were the composite at 42 months, each component of the composite, and death unrelated to pulmonary embolism or major bleeding at 18 and 42 months. All outcomes were reviewed and validated by a centralized adjudication committee.

Between July 2007 and October 2013, 104 patients were enrolled in the study. Over the 18-month treatment period, no patients in the warfarin group and 29.6% of patients in the placebo group (16/54) experienced the composite outcome (hazard ratio [HR], 0.03; 95% CI, 0.01-0.09; P <.001). Over the 42-month study period, the composite outcome occurred in 36.8% of patients (14/50) in the warfarin group and 31.5% of patients (17/54) in the placebo group (HR, 0.72; 95% CI, 0.35-1.46).

The authors concluded that “patients with a first episode of unprovoked proximal deep vein thrombosis should receive indefinite anticoagulation” but noted, “whether these findings apply to direct oral anticoagulants remains to be determined.”

Reference

1.     Couturaud F, Pernod G, Presles E, et al. Six months versus two years of oral anticoagulation after a first episode of unprovoked deep-vein thrombosis. The PADIS-DVT randomized clinical trial. Haematologica. 2019;104(7):1493-1501. doi:10.3324/haematol.2018.210971