Abstract
BackgroundThere is uncertainty regarding the safety and effectiveness of direct oral anticoagulant agents in patients with antiphospholipid syndrome (APS). We performed a multicenter feasibility study to examine our ability to identify and obtain consent from eligible APS patients and to obtain 95% adherence with daily rivaroxaban administration, in order to inform and power a larger study. Clinical outcomes of bleeding and thrombosis were also collected.MethodsAPS patients with prior venous thromboembolism (VTE) were recruited over 2 years (Oct 2014–Sept 2016) and followed for ≥ 1 year. Patients were assessed clinically every 3 months and had pill counts performed every 6 months. Numbers of patients fulfilling study criteria, as well as those consenting to participate, were tracked, and percentage adherence based on pill counts was recorded. These data were compared against the feasibility endpoints. Rates of thrombosis and bleeding were calculated. Criterion for feasibility was obtaining consent from 135 of 150 identified APS patients over 2 years.ResultsNinety-six eligible patients were identified, and 14 declined participation. Eighty-two patients were followed for a mean of 19 months, representing 129.8 patient-years. Average rivaroxaban adherence was 95.0%. During follow-up, there were 4 thromboembolic events (2 cerebrovascular and 2 VTE). There were no episodes of major bleeding.ConclusionsAdequately powered comparative trials using patient-important outcomes in APS are unlikely to be successful due to inability to recruit sufficient numbers of study subjects. This study does not reveal a higher than expected risk of recurrent thromboembolic disease compared to historical cohorts; however, this is an uncontrolled study in relatively low-risk APS patients.Trial registrationThe study was registered with clinicaltrials.gov, identifier NCT02116036, April 16, 2014.
Highlights
The antiphospholipid syndrome (APS) is characterized by clinical manifestations occurring in patients with persistent antiphospholipid antibody positivity [either anticardiolipin antibody, lupus anticoagulant (LA, otherwise known as non-specific inhibitor), and/or anti-beta-2 glycoprotein-1 antibody, positive on ≥ 2 occasions ≥ 12 weeks apart] [1]
A pilot study would allow for a more accurate estimate of enrollment capacity and consent rates, provide information regarding expected adherence, and allow for an estimate of rates of thrombosis and bleeding to inform a larger definitive study. In this pilot feasibility study, we explored the following feasibility outcomes: (a) we examined our ability to identify 150 eligible APS patients; (b) we measured our ability to obtain consent from 135 of these patients; and (c) we tested our hypothesis that we could obtain 95% adherence with daily rivaroxaban administration
Fourteen of 96 eligible patients declined consent, with the reasons stated being desire to remain on warfarin therapy (7/14), logistical, or no clear stated reason (e.g., “not interested,” 5/ 14)
Summary
The antiphospholipid syndrome (APS) is characterized by clinical manifestations (venous or arterial thrombosis and/or recurrent pregnancy loss) occurring in patients with persistent antiphospholipid antibody positivity [either anticardiolipin antibody (aCL), lupus anticoagulant (LA, otherwise known as non-specific inhibitor), and/or anti-beta-2 glycoprotein-1 antibody (aβ2GP1), positive on ≥ 2 occasions ≥ 12 weeks apart] [1]. Our multicenter collaborative research group has confirmed that the optimal therapy for the prevention of recurrent venous or arterial thrombosis in patients with APS is warfarin administered to achieve an international normalized ratio (INR) of 2.0–3.0 [4]. There is uncertainty regarding the safety and effectiveness of direct oral anticoagulant agents in patients with antiphospholipid syndrome (APS).
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