Real-world observational study to evaluate the effectiveness and safety of direct oral anticoagulants compared with vitamin K antagonists for secondary venous thrombosis prevention in low-risk thrombotic antiphospholipid syndrome patients: DOACS-APS protocol.

BACKGROUND: The therapeutic management of thrombotic antiphospholipid syndrome (APS) is based on indefinite anticoagulation. Vitamin K antagonists (VKA) remain the standard of care, particularly in patients with triple antiphospholipid antibody positivity or a history of arterial thrombosis. In low-risk patients, defined as those with single or double antiphospholipid antibody positivity and no prior arterial thrombosis, recent data suggest that direct oral anticoagulants (DOAC) may provide efficacy comparable to VKA. However, the quality of the available evidence is moderate to low. This study aims to compare the effectiveness of DOAC versus VKA in preventing thrombotic recurrence in low-risk patients with APS. METHODS: This is a multicentre, ambispective, observational, analytical study conducted in Internal Medicine departments across Spanish hospitals. Adult patients with low-risk thrombotic APS treated with DOAC or VKA will be included and followed for a minimum of two years. The primary effectiveness outcome will be venous thrombotic recurrence. CONCLUSIONS: The DOACS-APS study will provide clinically relevant real-world evidence on the effectiveness of DOAC in a selected subgroup of patients with APS, thereby improving therapeutic decision-making in routine clinical practice. The study is registered at ClinicalTrials.gov (NCT07372170).