Incidence of invasive fungal diseases in inflammatory bowel disease patients: A nationwide study in South Korea

Background: Limited reports exist regarding invasive fungal diseases (IFDs) in inflammatory bowel disease (IBD) patients.Objectives: This study aims to investigate the incidence and risk factors of IFDs, specifically invasive candidiasis, aspergillosis and pneumocystosis, in IBD patients in South Korea using nationwide data.Patients/Methods: A population-based retrospective cohort of 42,913 IBD patients between January 2010 and December 2018 was evaluated using the Health Insurance Review and Assessment database. The primary outcome was the incidence of IFDs, including invasive candidiasis, aspergillosis and pneumocystosis, while the secondary outcome involved analysing the risk factors associated with each specific infection.Results: The study included a total of 42,913 IBD patients, with 29,909 (69.7%) diagnosed with ulcerative colitis (UC) and 13,004 (30.3%) diagnosed with Crohn's disease (CD). IFDs occurred in 166 IBD patients (0.4%), with 93 cases in UC patients and 73 cases in CD patients. The incidence rates of invasive candidiasis, aspergillosis and pneumocystosis in IBD patients were 0.71 per 1000 person-years (PYs), 0.15 per 1000 PYs and 0.12 per 1000 PYs, respectively. The cumulative incidence of invasive candidiasis (adjusted p-value <.001) and Pneumocystosis (adjusted p-value = .012) was found to be higher in CD patients than in UC patients. Each IFD had different risk factors, including IBD subtypes, age at diagnosis, anti-tumour necrotic factor agents or the Charlson comorbidity index.Conclusion: Based on nationwide data in South Korea, this study shows that IFDs occur consistently in patients with IBD, albeit with a low frequency.