Incidence and risk factors of COVID-19 in patients with vasculitis in the first year of the pandemic: a Danish nationwide cohort study.

Background: To estimate the incidence of COVID-19 hospitalisation in patients with vasculitis, and to evaluate the impact of glucocorticoid treatment on the outcome between March 2020 and February 2021. Methods: With use of the Danish nationwide registers, a cohort of patients with large (LVV) and small vessel vasculitis (SVV), respectively, and general population controls (GPCs) matched on age and gender was established. Hazard ratios (HR) for COVID-19 hospitalisation was estimated. National COVID-19 surveillance data was used to calculate the odds ratio (OR) of having had a positive SARS-CoV2 PCR test. Lastly, a nested case-control design and conditional logistic regression was used to estimate the impact of glucocorticoids on the risk of hospitalisation. Findings: Patients with SVV (n=1090) had an increased incidence of COVID-19 hospitalisation compared with GPCs (comorbidity-adjusted HR 2·73; 95% CI 1·64-4·55), whereas no increased risk was seen in patients with LVV. Patients with vasculitis had similar likelihoods of having had a positive PCR test as GPCs. Glucocorticoids did not increase the HR of hospitalisation among patients with LVV or SVV. Interpretation: Patients with SVV were more likely to be admitted with COVID-19 than the GPCs. The impact of glucocorticoid treatment on the risk of hospitalisation needs further investigation. Funding Information: The study was sponsored by Aalborg University Hospital, Denmark. The funder had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication. Declaration of Interests: RLC, JL and SK have no disclosures or conflicts of interests. CTP has received grants for studies from Bayer and Novo Nordisk not relevant to the current study. LD has received research grant/research support from BMS, and speakers bureau from EliLilly and Galderma. Ethics Approval Statement: According to Danish legislation, no ethics approval is needed for register-based studies. The study has been approved by the Data Protection Committee of Northern Jutland, Denmark (2020-032).