Background/Purpose: The COVID-19 pandemic continues worldwide and has had a strong impact on public health. From the beginning of the pandemic, efforts were intensified to identify risk factors for development of the severe form of COVID-19.

In patients with rheumatic and musculoskeletal diseases (RMDs) and infected with COVID – 19, we aim to investigate the role of systemic autoimmune conditions compared to other type of RMDs in severity of COVID-19 in terms of hospital admissions.

Methods: An observational longitudinal study was conducted during the epidemic peak in Madrid (1stMar to 20thMay2020). All patients attended at the rheumatology outpatient clinic of a tertiary hospital with a diagnosis of RMDs and Covid-19 infection were included (according to a medical diagnosis or confirmed with a positive SARS-CoV-2 PCR diagnostic test). All patients were included since the time of COVID-19 diagnosis. The main outcome: hospital admissions related to COVID – 19 infection in patients with RMDs. Independent variable: Type of RMD including: autoimmune (systemic autoimmune conditions (SAC) and inflammatory join disease (IJD) and non – autoimmune diseases (mechanical diseases, and inflammatory diseases (mycrocrystaline arthritis and tendonitis)). Covariables: 1) Sociodemographic baseline characteristics. 2) Baseline comorbid conditions. 3) Treatment for the RMDs: a) Glucocorticoids, b) conventional syntethetic DMARDs (csDMARDs) and c) targeted syntethetic/biologic DMARDs (ts/bDMARDs). Statistical análisis: description of the sociodemographic, clinical and treatment characteristics of the patients. A multivariate logistic regression adjusted by age, sex and comorbidities was used to evaluate the risk of the different types of RMDs in hospital admissions related to COVID – 19. The results were expressed as OR with its corresponding confidence Interval (95% CI).

Results: 405 patients were included with RMDs and COVID – 19 infection. 69, 14% were women with a mean age at diagnosis of 60 ± 15,26 years. The evolution time from the diagnosis of RMD was 8 ± 8,4 years. Of the 405 patients, 243 (60%) had non – autoimmune RMD and 162 (40%) ((106 (65,43%) IJD and 56 (34,56%) SAC) had autoimmune RMD. 36% of all patients were admitted (31% from non – autoimmune RMDs, 36% for autoimmune RMD (IJD) and 57% for autoimmune RMD (SAC) (p =0,001). After adjusting by confounders, the risk of hospital admission in non -autoimmune RMD compared to SAC (OR: 0.28 [0.13-0.59], p = 0.001) and autoimmune RMD IJD compared to SAC (OR IJD: 0.34 [0.15-0.78], p = 0.011) was lower. Advanced age (OR: 1.10 [1.07-1.12], p < 0.001), male (OR female sex (OR: 0.59 [0.34-1.03], p=0.067) and more number of comorbidities (OR: 1.38 [1.01-1.88] increased the risk of hospitalization related to COVID-19.

Conclusion: One third of the RMD patients infected with COVID-19 required hospital admission. This study shows that patients with autoimmune and specifically with systemic autoimmune conditions have a higher risk of hospitalization related to COVID-19. We also show that advanced age, male sex and a higher number of comorbidities can contribute to worsen the prognosis of the COVID-19 disease.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/systemic-autoimmune-conditions-and-hospital-admissions-in-covid-19-infection/