Clinical course of COVID-19 infections in patients with Behçet’s disease in The Netherlands

Objective The aim of this study is to investigate the cumulative incidence and the severity of COVID-19 infections in patients with Behçet’s disease. Methods A retrospective cohort study of patients with Behçet’s disease was conducted. We obtained the data systematically from electronic patient files and through telephone interviews between February 2020 and May 1, 2021. The main outcomes were COVID-19 infection, disease duration, hospitalisation, intensive care admission and mortality. The secondary outcome was adherence to quarantine measures as recommended by the government. Results 185 Behçet’s disease patients were included (mean age 42.2 years, 54% female); 58% of the patients were receiving colchicine, 30% anti-TNFα, 16% azathioprine and 8% systemic steroids. 30 patients (16.2%) were positive for COVID-19. Within our cohort, the cumulative incidence of COVID-19 was therefore 16.2% (95% CI 11.2–22.3%), which is significantly increased when compared to the general Dutch population (8.7% (95% CI 8.72–8.73%)) (p<0.001). Four out of 30 (13%) patients were admitted to the hospital. There was no COVID-19 related mortality observed. Patients adhered to government measures; except in the period between the 1^st of June and the 28^th of September, this cohort received more visitors than in period 1 and 3. Conclusion In this cohort, Behçet’s disease patients have a higher risk for COVID-19 infection, without an increase of virus-related mortality. The course of COVID-19 disease in this cohort is relatively mild, with a lower admission rate than expected of patients using immunosuppressive medication.