Abstract: EPIDEMIOLOGICAL SCIENCE Clinical outcomes of hospitalised patients with COVID-19 and chronic inflammatory and autoimmune rheumatic diseases: a multicentric matched cohort study Jose L Pablos ‍ ‍,1,2 María Galindo,1 Loreto Carmona,3 Ana Lledó,1 Miriam Retuerto ‍ ‍,1 Ricardo Blanco ‍ ‍,4 Miguel A Gonzalez-­Gay ‍ ‍,4 David Martinez-­Lopez,4 Isabel Castrejón,5 José M Alvaro-­Gracia ‍ ‍,5 David Fernández Fernández ‍ ‍,6 Antonio Mera-­Varela ‍ ‍,6 Sara Manrique-­Arija ‍ ‍,7 Natalia Mena Vázquez ‍ ‍,7 Antonio Fernandez-­Nebro ‍ ‍,7 RIER Investigators Group Handling editor Josef S Smolen For numbered affiliations see end of article. Correspondence to Dr Jose L Pablos, Servicio de Reumatología, Instituto de Investigación Hospital 12 de Octubre, Madrid 28040, Spain; ​jlpablos@​h12o.e​ s Received 12 June 2020 Revised 31 July 2020 Accepted 31 July 2020 Published Online First 12 August 2020 © Author(s) (or their employer(s)) 2020. No commercial re-­use. See rights and permissions. Published by BMJ. To cite: Pablos JL, Galindo M, Carmona L, et al. Ann Rheum Dis 2020;79:1544–1549. 1544   ABSTRACT Objectives The impact of inflammatory rheumatic diseases on COVID-19 severity is poorly known. Here, we compare the outcomes of a cohort of patients with rheumatic diseases with a matched control cohort to identify potential risk factors for severe illness. Methods In this comparative cohort study, we identified hospital PCR+COVID-19 rheumatic patients with chronic inflammatory arthritis (IA) or connective tissue diseases (CTDs). Non-­rheumatic controls were randomly sampled 1:1 and matched by age, sex and PCR date. The main outcome was severe COVID-19, defined as death, invasive ventilation, intensive care unit admission or serious complications. We assessed the association between the outcome and the potential prognostic variables, adjusted by COVID-19 treatment, using logistic regression. Results The cohorts were composed of 456 rheumatic and non-­rheumatic patients, in equal numbers. Mean age was 63 (IQR 53–78) years and male sex 41% in both cohorts. Rheumatic diseases were IA (60%) and CTD (40%). Most patients (74%) had been hospitalised, and the risk of severe COVID-19 was 31.6% in the rheumatic and 28.1% in the non-­rheumatic cohort. Ageing, male sex and previous comorbidity (obesity, diabetes, hypertension, cardiovascular or lung disease) increased the risk in the rheumatic cohort by bivariate analysis. In logistic regression analysis, independent factors associated with severe COVID-19 were increased age (OR 4.83; 95% CI 2.78 to 8.36), male sex (1.93; CI 1.21 to 3.07) and having a CTD (OR 1.82; CI 1.00 to 3.30). Conclusion In hospitalised patients with chronic inflammatory rheumatic diseases, having a CTD but not IA nor previous immunosuppressive therapies was associated with severe COVID-19. Key messages What is already known about this subject? ►► There is limited evidence on the outcomes of COVID-19 in patients with rheumatic diseases and the impact of age, comorbidity, therapy or other factors associated to severity specifically in these patients. What does this study add? ►► We found that severe COVID-19 occurred in 31.6% of the rheumatic and 28.1% of non-­ rheumatic cohorts. ►► Having a connective tissue disease but not its therapy was significantly associated with severe COVID-19. ►► Other known risk factors as ageing or male sex also apply to patients with rheumatic diseases. How might this impact on clinical practice or future..