Decrease of Infectious Complications in Outpatients With Autoimmune Diseases From 2019 to 2020 Under the COVID-19 Pandemic: A Single-Center, Retrospective Cohort Study in Japan

OBJECTIVE: To examine how the novel coronavirus disease (COVID-19) has changed infectious complications in outpatients with autoimmune diseases. METHODS: We performed a retrospective, record-linked cohort study and questionnaire about lifestyle changes in patients who visited our department in 2019 and 2020. RESULTS: We surveyed 1316 outpatients in 2019 and 1284 in 2020. The most common underlying diseases were rheumatoid arthritis (842 vs. 814) and systemic lupus erythematosus (126 vs. 127). No significant difference in median age (66 vs. 67 years), respiratory comorbidities (30.4% vs. 32.0%), or corticosteroid use (42.2% vs. 44.3%) was found between the years. Immunomodulating agents were used more in 2020 (33.1% vs. 39.7%, p<.001). Total number of infections (28.0/100 vs. 19.4/100 person-years), pneumonia (3.6 vs. 1.6), influenza (2.1 vs. 0.1), and non-viral dermatological infections (3.8 vs. 2.1) were significantly lower in 2020. No significant difference was found for herpes zoster (2.2 vs. 1.8), urinary tract infections (3.3 vs. 3.8), or gastrointestinal infections (2.9 vs. 3.0). According to the questionnaire, 75% of the respondents became more conscious about wearing masks and 81% began to use hand sanitizer during the pandemic. CONCLUSION: Under the COVID-19 pandemic, some infectious complications have decreased in outpatients with autoimmune diseases.