1. The EINSTEIN CHOICE trial involved patients who had a history of venous thromboembolism (VTE) and had completed 6 to 12 months of therapeutic anticoagulation and were in equipoise regarding the need for continued anticoagulation.
2. In this population, rivaroxaban at a dose of 20 mg or 10 mg daily was associated with a lower risk of symptomatic recurrent fatal or nonfatal VTE compared to aspirin 100 mg daily, but also with numerically increased bleeding episodes.
Evidence Rating Level: 1 (Excellent)
Study Rundown: VTE, including deep-vein thrombosis (DVT) and pulmonary embolism (PE), is a highly morbid condition with a high rate of recurrence, particularly in patients without reversible risk factors. Long-term anticoagulation beyond 6 or 12 months has been associated with a decreased risk of recurrence, but this benefit must be weighed against an increased risk of bleeding events. In the EINSTEIN CHOICE trial, rivaroxaban at a dose of 20mg and 10mg daily was compared against aspirin at a dose of 100mg daily in patients who had a history of VTE and had completed 6 to 12 months of therapeutic anticoagulation and were in equipoise regarding the need for continued anticoagulation.
In this drug-company sponsored trial, there was a significantly lower rate of recurrent symptomatic fatal or nonfatal VTE in patients treated with both doses of rivaroxaban compared to placebo. At the same time, there was a minimally elevated risk of bleeding events in the rivaraxoban groups compared to aspirin. The trial provides support for clinicians looking to extend the treatment period with rivaroxaban for VTE beyond 6 to 12 months. Notably, the trial did not use overall mortality as an outcome, and it excluded patients who required extended treatment with therapeutic doses of anticoagulant agents. The study results only pertain to an extended period of up to 12 months beyond the initial 6 to 12 month treatment period; extending the findings to decision-making and risk/benefit balancing (particularly with regard to bleeding risk) for longer periods of time must be cautioned.
Relevant Reading: Oral rivaroxaban for symptomatic venous thromboembolism
In-Depth [randomized controlled trial]: This study involved 3396 patients recruited at 244 sites in 31 countries; patients were 18 years or older, had objectively confirmed proximal DVT or PE, and had been treated for 6 to 12 months with an anticoagulant agent; those requiring extended anticoagulation were excluded. Patients were randomized to receive rivaroxaban at a dose of 10 mg or 20 mg daily versus aspirin at a dose of 100mg daily. The primary efficacy outcome was the composite of symptomatic, recurrent fatal or nonfatal VTE or unexplained death for which PE could not be ruled out.
There was a significant benefit with respect to the primary outcome for both rivaroxaban arms compared to aspirin over the follow-up period (HR for 20 mg of rivaroxaban vs. aspirin 0.34, 95%CI 0.20 to 0.59; HR for 10 mg of rivaroxaban vs. aspirin 0.26, 95%CI 0.14 to 0.47; p < 0.001 for both comparisons). There was no statistically significant difference in the primary outcome rate between the two rivaroxaban arms, although the study was not powered to find one. Major bleeding occurred in 0.5%, 0.4%, and 0.3% of the rivaroxaban 20 mg and 10 mg and aspirin 100 mg groups, respectively. The numbers needed to treat for up to 12 months with rivaroxaban instead of aspirin to prevent one episode of fatal or nonfatal recurrent VTE were 33 and 30 for the 20 mg and 10 mg doses of rivaroxaban, respectively.
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