Final Analysis of COVID-19 Patients With Inflammatory Bowel Disease in Japan (J-COSMOS): A Multicenter Registry Cohort Study

Background and aims: Japan has experienced 8 waves of the coronavirus disease 2019 (COVID-19) outbreak over the past 3 years, resulting in an increasing number of deaths and incidence of severe infections. This study aimed to analyze the data from the Japanese inflammatory bowel disease (IBD) patients with COVID-19 registry (J-COSMOS) up to the eighth wave to investigate the clinical course of IBD patients with COVID-19 and factors contributing to disease severity.

Methods: In this multicenter, observational, cohort study, we analyzed a cohort of 1308 IBD patients diagnosed with COVID-19, enrolled across 77 participating facilities in the J-COSMOS registry from June 2020 to December 2022. Data on age, sex, IBD (classification, treatment, and activity), and COVID-19 (symptoms, severity, and treatment) were analyzed.

Results: The majority of patients (76%) were in clinical remission. According to the World Health Organization classification of COVID-19 severity, 98.4% of IBD patients had nonsevere disease, while 1.6% of patients had severe or critical disease. COVID-19 did not affect disease activity in most IBD patients. Stepwise logistic regression analysis revealed that high body mass index, and cerebrovascular disease were risk factors for severe COVID-19. Corticosteroids could affect COVID-19 severity, whereas anti-tumor necrosis factor α antibodies and thiopurines were associated with a reduced risk of severe COVID-19. No deaths were observed among IBD patients with COVID-19 registered in this cohort.

Conclusion: The impact of COVID-19 on IBD disease activity and factors associated with COVID-19 severity were consistent with findings of previous reports. No deaths in Japanese patients with IBD were observed.