Clostridioides difficile infections in Alberta: The validity of administrative data using ICD-10 diagnostic codes for CDI surveillance versus clinical infection surveillance

Background Clostridioides difficile infection (CDI) is one of the most common health care-associated infections. This study assessed the validity of the Discharge Abstract Database (DAD) compared to a traditional clinical surveillance method for identifying CDI. Methods Retrospective analysis of all DAD records with International Statistical Classification of Diseases and Related Health Problems 10th Revision (ie, ICD-10) diagnostic code A04.7 (enterocolitis due to CDI) between April 2015 and March 2019 were compared to a clinical dataset of positive inpatient CDI for all acute care facilities in Alberta, Canada. Sensitivity and positive predictive values were calculated using R version 3.6.0. Results The DAD had a sensitivity of 85.0% (95% confidence interval: 84.1%-85.8%) and a positive predictive value of 80.0% (95% confidence interval: 79.2%-80.0%). The CDI rate per 1,000 admissions over the study period was 28% higher in the DAD compared to Infection Prevention and Control surveillance. Discussion The DAD does not distinguish symptomatic cases from asymptomatic cases and so indicators to identify symptomatic disease would need to be applied, potentially through a linkage to antibiotic treatment orders available in patient management systems. Conclusions The DAD is moderately sensitive for identifying symptomatic CDI cases in Alberta, Canada and caution should be applied when interpreting rates based on administrative data.