Background/Purpose: Observational data have shown that rheumatic patients seem not to be more susceptible to SARS-CoV-2 infection neither to worse outcomes. However, the true prevalence of COVID-19 is still unknown due to the high proportion of subclinical infection. In this scenario, measuring the seroprevalence of SARS-CoV-2 may be crucial to improve the knowledge about the impact of COVID-19 in rheumatic patients.

The aim of this study is to estimate the prevalence of anti-SARS-CoV-2 antibodies in a large cohort of patients with rheumatoid arthritis or spondyloarthritis treated with biologic (b-) or targeted synthetic (ts-) DMARDs, living in a COVID-19 high-endemic area (Lombardy, Italy).

Methods: A seroprevalence cross-sectional study was conducted in the period between 4^th May and 16^th June 2020, including consecutive patients with confirmed RA or SpA treated with b- or tsDMARDs. Enrolled patients were tested for anti-SARS-CoV-2 IgG, IgM, and IgA antibodies against main viral antigens (nucleoprotein [N], receptor-binding domain [RBD]) using ELISA. Demographical and clinical data were also collected and patients were questioned about history of COVID-19 symptoms in order to identify potential factors that correlate with anti-SARS-CoV-2 positivity. Results were compared with those observed in the healthy population in the same period and region [1].

Results: The study population included 300 patients (62% females, mean age 53 years), diagnosed with RA (56%), psoriatic arthritis (23%), or ankylosing spondylitis (21%). Most patients were being treated with anti-TNF (57%), and the remainder were receiving abatacept (20%), anti-IL6 (11%), or JAK inhibitors (5%). Four patients (1.3%) referred a prior diagnosis of COVID-19 defined by nasopharyngeal swab. Immunoglobulin titers were evaluated resulting in 9%, 13.6%, and 13.3% positive patients for IgG, IgM, and IgA, respectively, with no significant difference to the healthy population. Among seropositive patients, 55.3% were asymptomatic, 16% had minor and 19.6% major symptoms, 7.1% were hospitalized. No deaths or admission to intensive care units occurred. No differences were found between seronegative and seropositive patients in relation to age, sex, rheumatic diagnosis, and treatments with b- or tsDMARDs. Conversely, corticosteroids therapy was associated with an increased risk of seropositivity in a dose-dependent manner with a significantly high OR for doses above 10 mg (OR 11.6, p 0.009). Relative increased risk was associated with the presence of at least one comorbidity (OR 5.25; 95%CI 1.95 – 14.08, p 0.001), especially hypertension (OR 5, p 0.001) and obesity (OR 5.4, p 0.01).

Conclusion: This study confirms that, even in a cohort of rheumatic patients, the spread of SARS-CoV-2 infection is much greater than that observed by capturing only swab-diagnosed COVID-19 cases, but consistent with healthy population. The underlying rheumatic disease and ongoing therapy with b/tsDMARD do not seem to impact SARS-CoV-2 antibody positivity, which conversely seems to be associated with the presence of comorbidities and with CS therapy. The project was co-financed by Lombardy Region 2014-2020 Regional Operational Programme under the European Regional Development Fund.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-true-prevalence-of-sars-cov-2-infection-in-an-italian-cohort-of-patients-with-inflammatory-arthritis-a-seroepidemiological-study/