A new study suggests that extending anticoagulant therapy for an additional year may be beneficial after patients with venous thromboembolism complete their initial course of therapy. The results of AMPLIFY-EXT (Apixaban after the Initial Management of Pulmonary Embolism and Deep Vein Thrombosis with First-Line Therapy-Extended Treatment) were presented at the annual meeting of the American Society of Hematology meeting in Atlanta and published simultaneously in the New England Journal of  Medicine.

After completing a standard anticoagulation regimen for 6-12 months, 2,486 VTE patients were randomized to either placebo or apixaban (2.5 or 5 mg twice daily) for an additional 12 months. At both doses, apixaban treatment was associated with a large reduction in clinical events and no increase in major bleeding events.

The primary endpoint, the composite of death or symptomatic recurrent VTE, was significantly reduced in the apixaban groups, from  11.6% in the placebo group to 3.8% in the low-dose apixaban and 4.2% in the high-dose apixaban groups (p<0.001 for both comparisons).

There were very few major bleeding events: 4 (0.5%) in the placebo group, 2 (0.2%) in the low dose apixaban group and 1 ((0.1%) in the high dose apixaban group. Clinically relevant non-major bleeds occurred in 2.3% of the placebo group, 3% of the low dose apixaban group, and 4.2% of the high dose apixaban group.

The investigators concluded that the results of the study “provide a rationale for continuing anticoagulation therapy” in VTE patients for whom there is uncertainty about the worth of continued anticoagulant therapy. They calculated that 14 patients would need to be treated to prevent one VTE case.