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DOACs Contraindicated APS — SCE Rheumatology MCQ

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ModerateSLE & Antiphospholipid SyndromeDOACs Contraindicated APSSCE Rheumatology

A 48-year-old woman has thrombotic antiphospholipid syndrome diagnosed after an ischaemic stroke. Repeat testing 12 weeks apart confirms persistent positivity for lupus anticoagulant, anticardiolipin IgG and anti-β2-glycoprotein I IgG. She is stable on warfarin (target INR 2.0–3.0) but asks to switch to a direct oral anticoagulant to avoid INR monitoring. Which statement best reflects the current evidence and UK guidance?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: D — A DOAC should not replace warfarin; the TRAPS trial found excess thrombotic events with rivaroxaban in triple-positive APS.

Explanation lettering: E = shown as B · B = shown as C · C = shown as E

This patient has high-risk thrombotic APS: persistent triple positivity and a prior arterial event. The TRAPS trial randomised triple-positive APS patients to rivaroxaban or warfarin and was terminated early because of an excess of thromboembolic events (including arterial events) in the rivaroxaban arm, showing no benefit and excess risk. The MHRA consequently advises that DOACs are not recommended in APS, particularly triple-positive patients, and that patients on a DOAC should be considered for switching to a vitamin K antagonist. So D is correct, and A and B are directly contradicted by TRAPS. C is wrong because the MHRA advice is a class-wide precaution covering apixaban, dabigatran and edoxaban; apixaban has no evidence of safety in APS, and a small randomised trial suggested excess strokes versus warfarin. E is wrong: any convenience or bleeding advantage is outweighed by increased recurrent thrombosis in this phenotype. She should remain on warfarin.

Reference: MHRA Drug Safety Update. Direct-acting oral anticoagulants (DOACs): increased risk of recurrent thrombotic events in patients with antiphospholipid syndrome. 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