Rheumatoid factor is associated with severe COVID‐19

Abstract

AbstractAimCoronavirus disease 2019 (COVID‐19) has been proposed as triggering autoimmunity. The aim of this study was to evaluate the presence and clinical significance of autoantibodies in patients with COVID‐19.MethodsWe retrospectively collected data from 245 patients who were hospitalized for COVID‐19. All patients were tested for the presence of antinuclear antibody (ANA), rheumatoid factor (RF), anti‐citrullinated peptide antibody (ACPA), and anti‐cytoplasmic neutrophil antibody (ANCA). Risk factors for death and critical COVID‐19, defined as the need for invasive mechanical ventilation or extracorporeal membrane oxygenation, were analyzed.ResultsNinety (36.7%) patients tested positive for ANA, and 51 (20.8%) patients tested positive for RF. Three patients each (1.2%) tested positive for ACPA and ANCA. RF‐positive patients had higher rates of invasive mechanical ventilation and death than RF‐negative patients (70.6% vs 28.4%, P < 0.001 and 45.1% vs 18.6%, P < 0.001, respectively). Underlying lung disease, kidney disease, heart disease, quick COVID severity index (qCSI), and lactate dehydrogenase (LDH) were associated with in‐hospital death. RF (odds ratio [OR] 7.31, 95% CI 2.50–21.37, P < 0.001), qCSI (OR 1.42, 95% CI 1.19–1.69, P < 0.001), and LDH (OR 1.004, 95% CI 1.002–1.005, P < 0.001) were associated with critical COVID‐19. Combination of RF, qCSI, and LDH showed good prognostic value (area under the curve = 0.903, P < 0.001) for critical COVID‐19.ConclusionsANA and RF were frequently detected in COVID‐19 patients. RF could be a risk factor for critical COVID‐19. The results of this study suggest immune dysfunction contributes to the complications of COVID‐19.