Autoimmune inflammatory rheumatic diseases and COVID-19 outcomes in South Korea: a nationwide cohort study

Background Real-world evidence on the association between autoimmune inflammatory rheumatic diseases, therapies related to these diseases, and COVID-19 outcomes are inconsistent. We aimed to investigate the potential association between autoimmune inflammatory rheumatic diseases and COVID-19 early in the COVID-19 pandemic. Methods We did an exposure-driven, propensity score-matched study using a South Korean nationwide cohort linked to general health examination records. We analysed all South Korean patients aged older than 20 years who underwent SARS-CoV-2 RT-PCR testing between Jan 1 and May 30, 2020, and received general health examination results from the Korean National Health Insurance Service. We defined autoimmune inflammatory rheumatic diseases (inflammatory arthritis and connective tissue diseases) based on the relevant ICD-10 codes, with at least two claims (outpatient or inpatient) within 1 year. The outcomes were positive SARS-CoV-2 RT-PCR test, severe COVID-19 (requirement of oxygen therapy, intensive care unit admission, application of invasive ventilation, or death), and COVID-19-related death. Adjusted odds ratios (ORs) with 95% CIs were estimated after adjusting for the potential confounders. Findings Between Jan 1 and May 30, 2020, 133 609 patients (70 050 [52 center dot 4%] female and 63 559 [47 center dot 6%] male) completed the general health examination and were tested for SARS-CoV-2; 4365 (3 center dot 3%) were positive for SARS-CoV-2, and 8297 (6 center dot 2%) were diagnosed with autoimmune inflammatory rheumatic diseases. After matching, patients with an autoimmune inflammatory rheumatic disease showed an increased likelihood of testing positive for SARS-CoV-2 (adjusted OR 1 center dot 19, 95% CI 1 center dot 03-1 center dot 40; p=0 center dot 026), severe COVID-19 outcomes (1 center dot 26, 1 center dot 02-1 center dot 59; p=0 center dot 041), and COVID19-related death (1 center dot 69, 1 center dot 01-2 center dot 84; p=0 center dot 046). Similar results were observed in patients with connective tissue disease and inflammatory arthritis. Treatment with any dose of systemic corticosteroids or disease-modifying antirheumatic drugs (DMARDs) were not associated with COVID-19-related outcomes, but those receiving high dose (>= 10 mg per day) of systemic corticosteroids had an increased likelihood of a positive SARS-CoV-2 test (adjusted OR 1 center dot 47, 95% CI 1 center dot 05-2 center dot 03; p=0 center dot 022), severe COVID-19 outcomes (1 center dot 76, 1 center dot 06-2 center dot 96; p=0 center dot 031), and COVID-19-related death (3 center dot 34, 1 center dot 23-8 center dot 90; p=0 center dot 017). Interpretation Early in the COVID-19 pandemic, autoimmune inflammatory rheumatic diseases were associated with an increased likelihood of a positive SARS-CoV-2 PCR test, worse clinical outcomes of COVID-19, and COVID-19related deaths in South Korea. A high dose of systemic corticosteroid, but not DMARDs, showed an adverse effect on SARS-CoV-2 infection and COVID-19-related clinical outcomes. Funding National Research Foundation of Korea. Copyright (c) 2021 Elsevier Ltd. All rights reserved.