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COVID-19, caused by SARS-CoV-2, can lead to severe inflammation and has been suggested to induce autoimmune phenomena. Multiple studies have reported autoantibodies in patients with COVID-19, particularly anti-cardiolipin, anti-β2-glycoprotein I and antinuclear antibodies.1 2 Anti-citrullinated protein antibodies (ACPA) and flaring of rheumatoid arthritis (RA) after SARS-Cov-2 infection have also been described.1 3 However, it is unclear how often ACPA occur after COVID-19 and whether they differ from ACPA normally found in patients with RA .
We have therefore performed a detailed investigation into ACPA positivity after COVID-19. To determine the seroprevalence of ACPA after COVID-19, ACPA was measured using routine tests or in-house ELISA in 61 patients visiting the post-COVID-19 outpatient clinic of the Leiden University Medical Center 5 weeks after hospitalisation. None of the patients tested positive for ACPA, except two patients previously diagnosed with ACPA-positive RA. Thus, we could not observe an increase in ACPA positivity after COVID-19.
Furthermore, we identified five patients across various Dutch rheumatology clinics presenting with polyarthritis compatible with RA after SARS-CoV-2 infection. To study the impact of COVID-19 on disease presentation, we closely examined their clinical phenotype and autoantibody characteristics (online supplemental table S1). All had suffered from moderate-to-severe COVID-19. On average, joint complaints started 6.6 weeks after infection, although two patients reported symptoms before infection. Four of five patients fulfilled the …
Footnotes
Handling editor Josef S Smolen
Contributors VD, TH, RT and DvdW designed the study. FLK, AvdB, AV and AR collected the patient data and materials. VD and TK performed the experiments. VD, TK and DvdW analysed the data. VD drafted the manuscript. All authors revised the manuscript critically and gave approval of the version to be published.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
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