key: cord-0956350-adorazuk authors: Kardaş, Rıza Can; Küçük, Hamit title: Factors influencing severe COVID‐19 in systemic vasculitis patients date: 2021-11-15 journal: Arthritis Rheumatol DOI: 10.1002/art.42022 sha: 31273ad2fc26c65ba9a1464b9db1626846a07a41 doc_id: 956350 cord_uid: adorazuk nan To the Editor: We read with great interest the article by Rutherford et al on the risk factors for severe COVID-19 in patients with systemic vasculitis (1) . This has been the first study published in the literature to describe the features of COVID-19 among a vasculitis-specific cohort. We have several points of interest: 9% of the COVID-19 cases in this study had a negative SARS-CoV-2 PCR result. Viral (including influenza) (2,3) and bacterial (4) co-infections and various opportunistic superinfections (5) have been reported in the literature. Were these cases investigated for other causes of respiratory infections? Secondly, vasculitis disease activity was determined by the global assessment of the physician. Given the majority (85%) of the COVID-19 cases were among ANCA-associated vasculitis patients, validated scoring systems like Birmingham Vasculitis Activity Score (6) and its modification for granulomatosis with polyangiitis (7) could have been used to denote the level of activity. Finally, no further information regarding the patients who have died was given in this study. For instance, given that the rate of active disease was high among these patients, did any of them die due to the complications of active vasculitis (rather than COVID-19)? Risk Factors for Severe Outcomes in Patients With Systemic Vasculitis and COVID-19: A Binational, Registry-Based Cohort Study Prevalence of Co-infection at the Time of Hospital Admission in COVID-19 Patients, A Multicenter Study COVID-19 and Influenza Co-infection: A Systematic Review and Meta-Analysis Bacterial infections in patients hospitalized with COVID-19 COVID-19-associated opportunistic infections: a snapshot on the current reports Modification and validation of the Birmingham Vasculitis Activity Score (version 3) A disease-specific activity index for Wegener's granulomatosis: modification of the Birmingham Vasculitis Activity Score. International Network for the Study of the Systemic Vasculitides (INSSYS)