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Autoimmune Inflammatory Disease Increases Risk of COVID-19 Hospitalization

"COVID-19 raises special concerns regarding its course and outcome among patients with IMIDs," investigators stated.

Patients with immune-mediated inflammatory diseases (IMIDs) were more likely to be hospitalized with COVID-19 when compared with non-IMID controls. This may be due in part to a higher burden of comorbidities in this patient population as well as other factors, including older age and the number and severity of comorbidities, according to a study published in The Journal of Rheumatology.1

“IMIDs are complex disorders caused by a combination of genetic susceptibility and environmental factors,” investigators stated. “Population-based studies have shown that > 5% of the general population have a diagnosis of ≥ 1 IMID. Patients with IMIDs are more susceptible to severe bacterial and viral infections. COVID-19 raises special concerns regarding its course and outcome among patients with IMIDs.”

A population-based, matched cohort study was conducted using data extracted from January 1, 2020, to July 31, 2020, in Ontario, Canada (which comprises 40% of the Canadian population). Separate cohorts were formed, including rheumatoid arthritis (RA), psoriasis (PsO), psoriatic arthritis (PsA), systemic autoimmune rheumatic diseases (SARDs), multiple sclerosis (MS), ankylosing spondylitis, inflammatory bowel disease, iritis, vasculitis, and polymyalgia rheumatica. Patients with IMIDs were matched with 5 non-IMID controls based on sociodemographic factors. Cumulative incidence of COVID-19-related hospitalizations and outcomes were compared between patients and controls.

In total, 493,499 patients with IMID (417 hospitalizations, 0.08%) were compared with 2,466,946 controls (1519 hospitalizations, 0.06%). Of those hospitalized, RA (32.1%) and PsO (27.6%) were the most common diagnoses.

Patients with IMIDs had significantly higher odds of being hospitalized for COVID-19 (matched unadjusted odds ratio [OR] 1.37, adjusted OR 1.23). Patients with RA (OR 1.42), iritis (OR. 1.46), SARDs (OR 1.47), MS (OR 1.83), vasculitis (OR 2.07), and PsA (OR 2.20) had a significantly higher risk than other rheumatic conditions. After adjusting for demographic factors and comorbidities in the multivariable analysis, patients with RA, PsA, and MS continued to have a significantly higher risk of hospitalization.

A total of 39.1% (n = 163/417) patients with IMIDs experienced complications during hospital admission, which was 21% higher in patients with IMIDs when compared with matched non-IMID patients. However, these odds were lowered after adjusting for comorbidities and demographic factors.

Additional risks included older age, multimorbidity, male sex, lower income, and long-term care residence. Comorbidities significantly associated with hospitalizations were dementia, diabetes, hypertension, asthma, chronic kidney disease, and cardiovascular disease.

The centralized data resource in a public health system with access to information of the entire population strengthened the study and reduced some of the limitations of previous research. However, misclassification of IMID diagnoses is possible, as they were based on diagnosis coding from physicians. Validated case definitions were used when available. Additionally, demographic characteristics and the population prevalence of IMIDs further validated the accuracy of diagnoses. Medication data was not included in the study; therefore, investigators were not able to assess the effect of immunosuppressives and other medications on hospitalizations. Finally, information about patients who died outside of the hospital, either before admission or after being discharged, was not available due to delays in reporting.

“Our results suggest that patients with IMIDs should be considered a high-risk group for developing severe COVID-19,” investigators concluded. “These data support advocacy and public health measures to reduce the risk of infection, such as promoting COVID-19 vaccinations among patients with IMIDs.”


Eder L, Croxford R, Drucker AM, et al. COVID-19 Hospitalizations, Intensive Care Unit Stays, Ventilation, and Death Among Patients With Immune-mediated Inflammatory Diseases Compared to Controls. J Rheumatol. 2022;49(5):523-530. doi:10.3899/jrheum.211012