The impact of diagnostic stewardship interventions on Clostridiodes difficile test ordering practices and results

Clostridiodes difficile infection (CDI) is a leading cause of healthcare associated infection and is associated with increased morbidity and mortality. Diagnostic stewardship is critical in optimizing testing accuracy for CDI. Multiple algorithms have been used for testing combining toxin A/B, glutamate dehydrogenase antigen and nucleic acid amplification test (NAAT) to enhance sensitivity. This study evaluated the effectiveness of two interventions on the rates and appropriateness of Clostridiodes difficile test orders and hospital-onset (HO) CDI. All Clostridiodes difficile orders and results in the study period (1/2018-2/2021) were included. To evaluate ordering appropriateness, we reviewed the medical charts of a random subsample of 100 orders that were collected from three periods within the study: pre-intervention and following each intervention. The first intervention was a clinical decision support system (CDSS) tool guiding providers to order testing only if CDI clinical criteria were met. The second intervention eliminated automatic NAAT reflex for indeterminate results and required antimicrobial stewardship team approval. A total of 3004 orders were registered during the study period. There was a 33% reduction in the rates of Clostridiodes difficile orders by the end of the study period (p < 0.001). The rates of reportable HO-CDI were significantly reduced by 57.1% (p = 0.003). We also noted a trend of increased appropriateness of testing overtime. In conclusion, combining CDSS intervention with NAAT reflex restriction was an effective tool to reduce inappropriate Clostridiodes difficile orders and decrease the rates of reportable HO-CDI.