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Biomarker studies
Original research
Loss of antiphospholipid antibody positivity post-thrombosis in SLE
  1. Muznay Khawaja1,
  2. Laurence Magder2,
  3. Daniel Goldman3 and
  4. Michelle A Petri1
  1. 1Department of Medicine, Division of Rheumatology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
  2. 2University of Maryland Medical Center, Baltimore, Maryland, USA
  3. 3Rheumatology, Johns Hopkins University, Baltimore, Maryland, USA
  1. Correspondence to Dr Michelle A Petri; mpetri{at}jhmi.edu

Abstract

Background/Purpose Loss of positivity of antiphospholipid antibodies has been observed in clinical practice post-thrombosis in patients with SLE with secondary antiphospholipid syndrome (APS). Our study defined the frequency of this loss and the duration before positivity recurred.

Methods In this prospective study, patients with SLE having at least two positive antiphospholipid markers prior to thrombosis and at least 1 year of follow-up after thrombosis were included. Antiphospholipid markers included lupus anticoagulant (dilute Russell viper venom test >45 s followed by mixing and confirmatory tests) and/or anticardiolipin titre (aCL IgG ≥20, aCL IgM ≥20 and/or aCL IgA ≥20). The percentage of visits with positive antiphospholipid markers after thrombosis was calculated. For patients with a negative antiphospholipid marker any time after thrombosis, survival estimates were performed to calculate the time to return of antiphospholipid positivity.

Results In APS due to SLE, complete loss of antiphospholipid positivity post-thrombosis was up to 41% for aCL IgG, 51% for IgM and 50% for IgA, but only 20% for those with lupus anticoagulant. Of those who at some point lost aCL IgG or became negative for lupus anticoagulant, the majority (60% and 76%, respectively) reacquired the antibody within 5 years. In contrast, of those who lost aCL IgM or IgA, fewer reacquired it within 5 years (37% and 17%, respectively).

Conclusion Intermittent positivity of antiphospholipid antibodies is present in APS due to SLE. These fluctuations make it difficult to decide on length of anticoagulation. Lupus anticoagulant is more likely to persist post-thrombosis.

  • antibodies
  • antiphospholipid
  • anticardiolipin
  • lupus erythematosus
  • systemic
https://creativecommons.org/licenses/by/4.0/

This is an open access article distributed in accordance with the Creative Commons Attribution 4.0 Unported (CC BY 4.0) license, which permits others to copy, redistribute, remix, transform and build upon this work for any purpose, provided the original work is properly cited, a link to the licence is given, and indication of whether changes were made. See: https://creativecommons.org/licenses/by/4.0/.

https://doi.org/10.1136/lupus-2020-000423

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    Footnotes

    • Contributors All authors have made substantial contributions to the conception, design, drafting, analysis, interpretation of data and revision of the work. All authors have given final approval of the version published and agreed to be accountable for all aspects of the work.

    • Funding The Hopkins Lupus Cohort is supported by NIH Grants AR043727 and AR069572.

    • Competing interests None declared.

    • Patient consent for publication Not required.

    • Ethics approval The Hopkins Lupus Cohort was approved on a yearly basis by the Johns Hopkins University School of Medicine Institutional Review Board (Study number NA_00039294). All patients gave written informed consent.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data availability statement Data are available on reasonable request. N/A.