An indirect comparison of dabigatran, rivaroxaban and apixaban for atrial fibrillation

New oral anticoagulant drugs are emerging as alternatives to warfarin for the prevention of stroke in patients with non-valvular atrial fibrillation. Two agents are direct factor Xa inhibitors (rivaroxaban and apixaban), and the third is a direct thrombin inhibitor (dabigatran). They have been separately compared to warfarin in large randomised trials. Our objective was to indirectly compare the three agents to each other for major efficacy and safety outcomes. Studies were assessed for comparability and the odds ratios of selected outcomes for each anticoagulant versus one another were estimated indirectly. The three cohorts differed significantly in terms of CHADS(2) score and the number of individuals with a past history of stroke, transient ischemic attack or systemic embolism. The estimated odds ratio of stroke or systemic embolism was 1.35 for rivaroxaban vs dabigatran 150 mg (p=0.04), 0.97 for rivaroxaban versus dabigatran 110 mg (p=0.81), 1.22 for apixaban versus dabigatran 150 mg (p=0.18), 0.88 for apixaban versus dabigatran 110 mg (p=0.34) and 0.90 for apixaban versus rivaroxaban (p=0.43). The estimated odds ratio of major bleeding was 1.10 for rivaroxaban versus dabigatran 150 mg (p=0.36), 1.28 for rivaroxaban versus dabigatran 110 mg (p=0.02), 0.74 for apixaban versus dabigatran 150 mg (p=0.004), 0.87 for apixaban versus dabigatran 110 mg (p=0.17) and 0.68 for apixaban versus rivaroxaban (p<0.001). In conclusion, the available data indicate no significant difference in efficacy between dabigatran 150 mg and apixaban for the prevention of stroke or systemic embolism in patients with non-valvular atrial fibrillation. It appears however that apixaban is associated with less major bleeding than dabigatran 150 mg or rivaroxaban and that rivaroxaban is less effective than dabigatran 150 mg in preventing stroke or systemic embolism. Such an indirect comparison should be used only to generate hypotheses which need to be tested in a dedicated randomised trial comparing the three drugs directly.