Correspondence on 'Onset of rheumatoid arthritis after COVID-19: coincidence or connected?'

TLDR: In this paper, the authors have conducted serology studies on 61 patients and found no increase in the incidence of anti-citrullinated cyclic peptide (anti-CCP) antibodies.

Abstract: We read with great interest the letter by Derksen et al on ‘Onset of rheumatoid arthritis (RA) after COVID-19: coincidence or connected?’ in which they have conducted serology studies on 61 patients, 5 weeks after COVID-19 infection and found no increase in the incidence of anti-citrullinated cyclic peptide (anti-CCP) antibodies.1 Also, they found that the clinical and autoantibody characteristics of three patients from another cohort with seroconversion were similar to the regular patients with RA. Based on this, they have proposed that RA after COVID-19 may be a coincidence rather than connected. Triggering of autoimmunity by severe COVID-19 infection has been proposed2 and shown by demonstration of various autoantibodies, mainly antinuclear antibodies, antineutrophil cytoplasmic antibodies and antiphospholipid antibodies (APLA), in the sera of such patients.3 4 Autoimmune diseases like lupus, Kawasaki disease, systemic vasculitis, APLA syndrome and reactive arthritis have been reported post COVID-19.3 Multiple arthritic manifestations of COVID-19 infection have been reported including a few cases of reactive arthritis5 6 and a few of seropositive RA.1 7 8 However, information on arthritis-related antibodies …