New oral anticoagulants in the treatment of acute venous thromboembolism - a systematic review with indirect comparisons

Background: For decades, heparins and vitamin K antagonists (VKAs) have been the gold standards in therapy of venous thromboembolism (VTE). The advent of factor IIa and Xa inhibitors provides new therapeutic options. The aim of this analysis is to compare the currently available new oral anticoagulants (NOACs) with VKAs and also indirectly the NOACs with each other, as it is unlikely that a head-to-head comparison will ever be available. Patients and methods: In total, 27,024 patients were included in the RE-COVER, RE-COVER II, EINSTEIN DVT and PE, AMPLIFY and HOKUSAI studies with 13,511 in the VKA arm and 13,513 in the NOAC arm. Efficacy and safety endpoints were assessed by relative risks (RR) and absolute risk reductions (ARR) relative to VKA. The indirect comparison between the NOACs was performed according to ISPOR guidelines. Results: No differences between NOACs and VKA were found regarding recurrent VTE and death. Bleeding was significantly reduced by NOACs: major bleeding by rivaroxaban (RR 0.55; 0.38 - 0.81) and apixaban (RR 0.31; 0.17 - 0.55); major and clinically relevant non-major bleeding by dabigatran (RR 0.63; 0.51 - 0.77), apixaban (RR 0.44; 0.36 - 0.55) and edoxaban (RR 0.81; 0.71 - 0.93). The ARR for major bleeding was 1 % for rivaroxaban and apixaban; and for the composite bleeding endpoint 3.2 % for dabigatran, 5.4 % for apixaban, and 1.9 % for edoxaban. Regarding efficacy, no differences were found between NOACs. Apixaban reduced incidence of major bleeding more than dabigatran and edoxaban. Regarding occurrence of the composite bleeding endpoint, apixaban performed better than all other NOACs and dabigatran better than rivaroxaban and edoxaban. Conclusions: NOACs are as efficient in the treatment of VTE as VKA but with reduced risk of bleeding complications. Indirect comparisons indicate differences in the risk of clinically relevant bleeding events. Important issues such as monitoring and reversal of anticoagulation are still unresolved, but introduction of NOACs increased the therapeutic spectrum and thereby the potential for individualized therapy.