Effectiveness and safety of novel oral anticoagulants as compared with vitamin K antagonists in the treatment of acute symptomatic venous thromboembolism: a systematic review and meta- analysis

IntroductionNew direct oral anticoagulants (NOACs) constitute a novel treatment option for acute venous thromboembolism (VTE), with practical advantages. Individual studies have demonstrated comparable efficacy to that of vitaminK antagonists (VKAs) and have suggested a more favorable safety profile . We performed a meta-analysis to determine the efficacy and safety of NOACs as compared with those of VKAs in patients with acute VTE. MethodsWe searched MEDLINE, EMBASE, the Cochrane Database of Systematic Reviews and the Clinical Trials Registry up to October 2013. Eligible studies included phase3 trials comparing NOACs with VKAs in patients with acute VTE. Relative risks (RRs), absolute risk differences and numbers needed to treat (NNTs) to prevent one event were calculated for recurrent VTE, fatal pulmonary embolism (PE), overall mortality, major bleeding, and other bleeding complications, with random-effects models. ResultsFive studies were included, investigating four NOACs (rivaroxaban, dabigatran, apixaban, and edoxaban) in 24455 patients with acute VTE. RRs for recurrent VTE, fatal PE and overall mortality for NOACs vs. VKAs were 0.88 (95% confidence interval [CI]0.74-1.05), 1.02 (95%CI0.39-5.96), and 0.97 (95%CI0.83-1.14), respectively. The RR for major bleeding was 0.60 (95%CI0.41-0.88). The NNT with NOACs instead of VKA to prevent one major bleed was 149. The RR and NNT for fatal bleeding were 0.36 (95%CI0.15-0.87) and 1111. A fixed-effect network analysis did not demonstrate significant differences between individual NOACs and rivaroxaban. ConclusionsNOACs have comparable efficacy to that of VKAs, and are associated with a significantly lower risk of bleeding complications, although the NNT to prevent one major bleed was relatively high.