Antiphospholipid syndrome (APS) is an acquired autoimmune disease characterised by presence of thrombosis and/or pregnancy morbidity with persistently positive antiphospholipid antibodies(aPL). Due to the heterogeneity and relative rarity of this disorder clinical practice in the management of APS remains varied. In this retrospective UK-wide multicentre study, we aimed to delineate clinical practice and outcomes in thrombotic APS to improve the areas of limited knowledge, particularly anticoagulant practice, thrombotic recurrence and bleeding. Anticoagulation in Antiphospholipid Syndrome (A2PLS) is the largest multicentre observational study to date spanning 20 national health service Trusts in the UK and including 500 adult patients (≥18years) with thrombotic APS, on or off anticoagulation during the years 2012-2021. Thrombotic APS is primarily treated with vitamin K antagonists; however, the rates of recurrent thrombosis remain high. In the last decade, recurrent thrombosis occurred in 34.4% (43/125), 32.6% (31/95) and 39.8% (37/93) of single, dual and triple positive aPL patients respectively with a recurrence rate of 46%. There was no difference in the probability of recurrent thrombosis based on the number of positive aPL tests (p=0.82) especially in the first three years. However, the probability of recurrent thrombosis was significantly higher in patients with lupus anticoagulant (p0.01) compared to presence of other antibodies. There was a higher probability of recurrence in patients with arterial than venous thrombosis (p=0.03). Overall, 10-year bleeding rate was 22.0% with 6.7% patients having major bleeding. Identifying APS patients at higher risk of recurrent thrombosis remains a challenge and current risk stratification is not adequate.
Crossette-Thambiah et al. (Fri,) studied this question.