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APS with HCQ — SCE Rheumatology MCQ

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HardSLE & Antiphospholipid SyndromeAPS with HCQSCE Rheumatology

A 55-year-old woman has clinically inactive SLE and triple-positive thrombotic antiphospholipid syndrome. She develops a further objectively confirmed proximal deep-vein thrombosis despite verified adherence to warfarin and consistently therapeutic anticoagulation with an INR of 2.0–3.0. Her anticoagulation strategy is being reviewed separately by the multidisciplinary team. She is not currently taking hydroxychloroquine and has no contraindication to it. Which statement best describes the rationale for adding hydroxychloroquine?

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Reveal the answer and explanation

Correct answer: D — It may attenuate aPL-mediated platelet, endothelial and complement activation, providing adjunctive thromboprotection.

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

Hydroxychloroquine has pleiotropic antithrombotic and immunomodulatory effects relevant to APS, including attenuation of aPL-mediated platelet activation, endothelial and monocyte tissue-factor expression, complement-related inflammation and disruption of anticoagulant cell-surface mechanisms. Clinical evidence is limited but suggests that it may reduce thrombotic risk when added to standard antithrombotic treatment, particularly in an SLE context. It is therefore an adjunct, not a thrombolytic or substitute for anticoagulation. It neither directly activates fibrinolysis nor inhibits vitamin K epoxide reductase, so A and B are incorrect. It may have thrombosis-modifying effects despite therapeutic anticoagulation, excluding C. Although reductions in aPL titres have been reported, reliable antibody eradication or seronegativity is not its therapeutic mechanism or target, excluding D. Anticoagulation escalation must still be considered separately for recurrent thrombotic APS.

Reference: Arachchillage DJ, Laffan M, Pericleous C. Hydroxychloroquine as an Immunomodulatory and Antithrombotic Treatment in Antiphospholipid Syndrome. International Journal of Molecular Sciences. 2023. https://pubmed.ncbi.nlm.nih.gov/36674847/