Abstract: Rheumatology Rheumatology 2021;60:SI59–SI67 doi:10.1093/rheumatology/keaa897 Advance Access publication 28 December 2020 Original article Incidence and severeness of COVID-19 hospitalization in patients with inflammatory rheumatic disease: a nationwide cohort study from Denmark Objectives. To estimate the incidence of COVID-19 hospitalization in patients with inflammatory rheumatic disease (IRD); in patients with RA treated with specific DMARDs; and the incidence of severe COVID-19 infection among hospitalized patients with RA. Methods. A nationwide cohort study from Denmark between 1 March and 12 August 2020. The adjusted incidence of COVID-19 hospitalization was estimated for patients with RA; spondyloarthritis including psoriatic arthritis; connective tissue disease; vasculitides; and non-IRD individuals. Further, the incidence of COVID-19 hospitalization was estimated for patients with RA treated and non-treated with TNF-inhibitors, HCQ or glucocorticoids, respectively. Lastly, the incidence of severe COVID-19 infection (intensive care, acute respiratory distress syndrome or death) among hospital-admitted patients was estimated for RA and non-IRD sp - individudals. Results. Patients with IRD (n ¼ 58 052) had an increased partially adjusted incidence of hospitalization with COVID-19 compared with the 4.5 million people in the general population [hazard ratio (HR) 1.46, 95% CI: 1.15, 1.86] with strongest associations for patients with RA (n ¼ 29 440, HR 1.72, 95% CI: 1.29, 2.30) and vasculitides (n ¼ 4072, HR 1.82, 95% CI: 0.91, 3.64). There was no increased incidence of COVID-19 hospitalization associated with TNF-inhibitor, HCQ nor glucocorticoid use. COVID-19 admitted patients with RA had a HR of 1.43 (95% CI: 0.80, 2.53) for a severe outcome. Conclusion. Patients with IRD were more likely to be admitted with COVID-19 than the general population, and COVID-19 admitted patients with RA could be at higher risk of a severe outcome. Treatment with specific DMARDs did not affect the risk of hospitalization. Key words: rheumatoid arthritis, epidemiology, viruses, DMARDs, biological therapies, immunosupressants Rheumatology key messages Patients with IRD had higher incidence of COVID-19 hospitalisation compared with the general population of Denmark. Among patients with RA, the COVID-19 hospitalisation rates were not higher among those treated with hydroxychlorquine, TNF-inhibitor or glucocorticoids. . COVID-19 admitted patients with RA had a tendency towards a higher incidence of severe outcome, but this was not statistically significant. . . 1 Department of Rheumatology, Aalborg University Hospital, Aalborg, 2Department of Rheumatology, Center for Rheumatology and Spine Diseases, Gentofte Hospital, Hellerup, 3Lupus and Vasculitis Clinic, Center for Rheumatology and Spine Diseases, Rigshospitalet, Copenhagen, 4Department of Clinical Medicine, Aalborg University, Aalborg, 5Department of Infectious Diseases, Aalborg University Hospital, Aalborg, 6Department of Cardiology, Nordsjællands Hospital, Hillerod and 7The DANBIO Register, Denmark Submitted 10 November 2020; accepted 8 December 2020 Correspondence to: René Cordtz, Department of Rheumatology, Aalborg University Hospital, Reberbansgade 15, DK-9000 Aalborg, Denmark. E-mail: r.cordtz@rn.dk//rcordtz@gmail.com *René Cordtz and Jesper Lindhardsen contributed equally to this study. C The Author(s) 2020. Published by Oxford University Press on behalf of the British Society for..