(242) Clostridioides difficile Infection in South Korea: Retrospective Study on Annual Incidence Rates and Treatment Status

Background: The burden of Clostridioides difficile infection (CDI) in South Korea has remained unclear, primarily due to the absence of a reliable algorithm for identifying CDI cases and a comprehensive surveillance system.

Objectives: This study aims to examine the epidemiology of CDI in South Korea from 2015 to 2021, with a focus on incidence rates. Additionally, we assessed healthcare utilization characteristics, including the pattern of drug utilization for CDI management, based on the presence of a CDI diagnosis.

Methods: A national retrospective cohort of CDI cases was established using Korean National Health Insurance claims data from 2015 to 2021. CDI cases were identified through hospitalization records, which included a CDI diagnosis code (ICD-10: A047) or documentation of CDI laboratory testing with oral vancomycin prescription. We calculated total and annual CDI incidence rates per 100,000 person-years, using population data from the Korean Statistical Information Service. We stratified the cohort by CDI diagnosis to assess differences in patient demographics, healthcare institution characteristics, and healthcare utilization, including length of stay and cost per hospitalization, using chi-square or t-tests as appropriate. Drug utilization for CDI treatment was evaluated annually within each stratified cohort.

Results: We included a total of 238,062 CDI cases in the analysis including 30,588 (12.8%) undiagnosed cases. From 2015 to 2021, the overall annual incidence rate of CDI has gradually increased from 247.2/100,000 person-year in 2015 to 456.2/100,000 person-year in 2021. The undiagnosed group had longer length of stay (66.0 vs 53.4 days), higher cost per hospitalization (22,001 USD vs. 15,788 USD), higher surgery rate (63.2% vs 56.1%), and higher In-hospital death rate (0.08% vs 0.03%). The majority of undiagnosed CDI cases were admitted through the emergency room (51.2%) and managed at tertiary hospital (54.8%) while 56.5% the diagnosed CDI cases were admitted through outpatient visit. The most frequently used drug to treat CDI was metronidazole in both diagnosed and undiagnosed CDI, at 59.4% (n=123,268) and 65.9% (n=20,148) respectively.

Conclusions: The CDI incidence in Korea has doubled from 2015 to 2021, with metronidazole being the most frequently used treatment. Our analysis likely underestimates the true incidence of CDI and the utilization rate of metronidazole, as it excluded undiagnosed patients treated solely with metronidazole alone, without the use of oral vancomycin. Significant differences were observed in the management of diagnosed and undiagnosed CDI, particularly in terms of patient characteristics and healthcare utilization, including costs.