1c - Inclusion of Emergency Department attendance on onset status classification of Clostridioides difficile infections (CDI): A revised definition and implications on hospital-onset CDI cases in England

Background : Hospitalisations often occur after attendance to an Emergency Department (ED). Infection prevention control are a major challenge in EDs due to its high-paced and high-volume nature, with mounting pressure as ED activity continues to rise. Surveillance of Clostridiodies difficile infections (CDI) is mandated in England, with cases categorised as either Hospital-onset (HO) or Community onset (CO). Ensuring the accurate categorisation of cases is key in monitoring the source of these infections.

Methods : CDI cases reported to UKHSA Mandatory Surveillance Data Capture System (DCS) between January 2020 and December 2023 were linked to the Emergency Care Dataset (ECDS) to identify ED attendances within 1 day of the DCS-recorded hospital admission date. We compared the existing definition of HO;  greater than two days from hospital admission to positive specimen date, against a modified definition where ED arrival date is used as the start point, when cases are admitted from ED.

Results : During this period, 58,084 CDI cases were reported to the DCS. Of these, we identified 34,911 (60.1%) with a prior ED attendance.  Using the conventional onset definition, 25,014 (43.1%) were ascertained as HO CDI cases, which increases to 26,587 (45.8%) once ED attendance was included, 6.3% increase. We note more cases shifting to HO classification annually, 2020–4.0%; 2021–5.8%; 2022–7.3% and 2023 7.2%. This coincides with increased duration in EDs in our cohort, with 3.7% of attendances spanning over one day in 2023 compared to 0.23% in 2020.

Conclusions : We observe an increasing proportion of CDI cases reclassified to HO from CO when adjusting current definitions to include duration in ED prior to hospitalisation. Not only does this reclassification have implications on accurate reporting, but interventions.