Comparative Burden of COVID-19 in Adults with Rheumatic Diseases and Immunocompetent Individuals: A Population-Based Cohort Study in Quebec, Canada, 2020-2023
Across the major phases of the COVID-19 pandemic from March 2020 to April 2023, this study compared the burden of severe COVID-19 among individuals with systemic autoimmune rheumatic diseases (SARDs) versus immunocompetent individuals with and without comorbidities.
This population-based cohort study used administrative datasets to estimate crude and age- and sex-standardized SARS-CoV-2 and severe COVID-19 incidences among adults >18 years with SARDs, chronic comorbidities, or no comorbidities. Relative to adults without comorbidities, Cox models were used to derive adjusted hazard ratios (aHRs) for infection, hospitalization, and intensive care unit admission or death (ICU/death) during three periods: pre-vaccination (March–December 2020), vaccination pre-Omicron (December 2020–December 2021), and Omicron (December 2021–April 2023).
The study included 81,434 adults with SARDs and 2,020,356 with comorbidities versus 3,144,700 without comorbidities. Despite similar adjusted infection rates, the SARDs cohort had higher risks of hospitalization and ICU/death during the pre-vaccination period (aHRs: 3.4, 95%CI: 2.8–4.1; and 4.0, 95%CI: 2.8–5.7, respectively), and these risks persisted through the Omicron period (aHRs: 4.5, 95%CI: 4.0–4.9; and 4.4, 95%CI: 3.6–5.4, respectively). Among SARDs, rheumatoid arthritis, psoriatic arthritis, and systemic lupus erythematosus contributed the highest burden, with comparable hospitalization and mortality rates among younger rheumatoid arthritis patients versus healthy older adults. Patients treated with highly immunosuppressive rituximab or mycophenolate had the highest hospitalization and ICU/death risks, particularly during the Omicron period (aHRs: 11.9, 95%CI: 9.9–14.3; and 17.6, 95%CI: 13.0–23.9, respectively).
The authors conclude that individuals with SARDs, especially those receiving highly immunosuppressive therapies, experienced elevated COVID-19 burden and severe outcome risks throughout the pandemic, warranting their prioritized consideration during future public health emergencies.