Poster Session I: Thrombosis and vascular biology - Biology - translational research
Anticoagulation is the mainstay of acute venous thromboembolism (VTE) therapy. Until recently Vitamin-K antagonists (VKAs) were the standard of care for extended treatment of VTE. In the last decade, direct oral anticoagulants (DOACs) have been studied and approved for use in treatment and secondary prevention of VTE. The apixaban AMPLIFY-EXTEND clinical trial and the rivaroxaban EINSTEIN CHOICE study, have offered evidence that low dose anticoagulation up to 12 months following completion of standard VTE treatment, can be equally effective to standard dose apixaban/rivaroxaban for secondary prevention of thromboembolism. To date there is no real-life study recording the outcomes of patients on low dose DOACs in this setting.
In this audit, we sought to identify patients on long term low dose apixaban/rivaroxaban for secondary prevention of VTE and record their outcomes.
Between January 2015 and September 2018, 4,625 patients were initiated to DOACs in our clinics. Amongst them 394 patients were put on either apixaban 2.5 mg bd (N = 352) or rivaroxaban 10 mg od (N = 42). Their median age was 65(16-98) years. The index event to offer long term anticoagulation was unprovoked VTE in 271 patients while 123 had suffered a provoked VTE with permanent risk factors. Cancer-associated thrombosis was recorded in 42 patients, 69 individuals had documented thrombophilia and/or family history of thrombosis. Recurrent VTE was recorded in 41 patients. The median time from thrombosis to low-dose anticoagulation switch was 7.26(3-280) months. The median follow-up time on low dose anticoagulation was 15(3-45) months.
Major bleeding occurred in 3/394 patients (0.76%), all 3 patients were on low dose apixaban. Major plus clinically relevant non-major bleeding was recorded in 30 patients (7.6%). Recurrent VTE occurred in 13/352 patients (3.69%) in the apixaban group and 1/42 patients (2.3%) in the rivaroxaban group (p = NS). No statistical differences in bleeding rate and VTE recurrence were identified between the total patient population, the cancer related thrombosis and the thrombophilia/family history of VTE subgroup respectively (table).
Our study although small, is the first to record the clinical experience of using long term low dose DOACs to prevent VTE recurrence in real life. Our results confirm that low dose DOACs are very safe with major bleeding rate oof <1% in 15 months. We did however find a higher incidence of recurrent VTE (3.55%) compared to the AMPLIFY-EXTEND (1.7%) and the EINSTEIN CHOICE (1.2%) trials.