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Antiphospholipid Syndrome — SCE Rheumatology MCQ

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ModerateSLE & Antiphospholipid SyndromeAntiphospholipid SyndromeSCE Rheumatology

A 38-year-old woman has definite thrombotic antiphospholipid syndrome following an unprovoked proximal deep-vein thrombosis. She is persistently positive for lupus anticoagulant, anticardiolipin antibodies and anti-β2-glycoprotein I antibodies. She remains well on warfarin with a target INR of 2–3 but asks to change to a direct oral anticoagulant to avoid INR monitoring. What is the most appropriate long-term antithrombotic strategy?

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Correct answer: E — Continue warfarin at INR 2–3 and avoid switching to a DOAC

The correct answer is E. She has thrombotic APS with a high-risk, persistently triple-positive antibody profile and an unprovoked venous thrombosis, so long-term vitamin K antagonist therapy with a target INR of 2–3 is appropriate. UK MHRA advice states that DOACs are not recommended in thrombotic APS, particularly in triple-positive patients. In TRAPS, triple-positive patients receiving rivaroxaban experienced excess thrombotic events compared with warfarin. This concern is not confined sufficiently to rivaroxaban to justify switching to apixaban. Anticoagulation should not be stopped after 3 months, and aspirin alone is inadequate secondary prevention following APS-associated DVT. Warfarin and DOACs should therefore not be presented as equivalent. Importantly, DOACs are described as not recommended rather than formally contraindicated.

Reference: Medicines and Healthcare products Regulatory Agency. Direct-acting oral anticoagulants (DOACs): increased risk of recurrent thrombotic events in patients with antiphospholipid syndrome. Drug Safety Update, 19 June 2019. https://www.gov.uk/drug-safety-update/direct-acting-oral-anticoagulants-doacs-increased-risk-of-recurrent-thrombotic-events-in-patients-with-antiphospholipid-syndrome