Apixaban versus vitamin K antagonists in patients with antiphospholipid syndrome: a cohort study

Current guidelines recommend that direct anticoagulants should not be used in prevention of recurrent thrombosis in patients with antiphospholipid syndrome (APS). However, except for triple-positive APS and rivaroxaban use, little evidence supports such recommendation. In a real-life cohort study, we evaluated the risk of thromboembolism and bleeding in APS patients on apixaban versus vitamin K antagonists (VKA). We enrolled 152 APS patients (aged 44 [interquartile range 36-56], 83% women), including 66 patients treated with apixaban 5 mg bid and 86 with warfarin (target INR [international normalized ratio] 2-3). During a median follow-up of 53 months, we recorded venous thromboembolism (VTE), ischemic stroke or myocardial infarction, along with major bleeding. We observed 4 (6.1%, 3 VTE and 1 ischemic stroke) thrombotic events in patients on apixaban and 12 events (14%, 9 VTE, 2 ischemic strokes and 1 myocardial infarction) in VKA patients. APS patients on apixaban had similar risk of recurrent thromboembolism compared to those on warfarin (HR=0.327, 95% CI: 0.104-1.035). Thromboembolic events occurred less commonly in statin users (8% vs 50%, p=0.01) and more frequently in triple-positive APS (50% vs 22.1%, p=0.028) and in subjects with higher D-dimer at baseline (p=0.023); the latter difference was present in the apixaban group (p=0.02). Patients on apixaban had similar risk of major bleeding compared to warfarin (HR=0.54, 95% CI: 0.201-1.448). In real-life APS patients apixaban appears to be similar to VKA for the prevention of thromboembolism and risk of bleeding, which might suggest that some APS patients could be treated with apixaban.