Anticoagulants in Antiphospholipid Syndrome

The Therapeutic Goods Administration (TGA) is updating product information documents for direct acting oral anticoagulants (DOACs) to advise of the increased risk of recurrent thrombotic events in patients with antiphospholipid syndrome. Antiphospholipid syndrome is an autoimmune disorder in which patients develop antibodies to phospholipid-bound proteins. Patients with this condition are at an increased risk of thrombosis and standard treatment involves the use of anticoagulants.

Anticoagulants include heparin, warfarin, and DOACs. The three DOACs available in Australia are apixaban, dabigatran etexilate, and rivaroxaban. This new warning is based on results from the Trial on Rivaroxaban in AntiPhospholipid Syndrome (TRAPS) study conducted in patients with antiphospholipid syndrome who have a history of thrombosis and a high risk of recurrent events. This study demonstrates an increased risk of thrombotic events with rivaroxaban compared to warfarin. Thromboembolic events occurred in 21% of patients in the rivaroxaban group compared to 0% for patients in the warfarin group. Major bleeding events were reported in 7% of patients in the rivaroxaban and 3% in the warfarin group. While the study only investigated rivaroxaban, other DOACs may be associated with a similar risk.

The TGA advises that DOACs are not recommended for patients with antiphospholipid syndrome, particularly those who are considered high-risk. If these patients are currently receiving a DOAC, it may be appropriate to consider changing to an alternative anticoagulant.