National Healthcare Safety Network laboratory-identified Clostridium difficile event reporting: A need for diagnostic stewardship

•Healthcare facility-onset Clostridium difficile Laboratory Identification (HO-CDI LabID) events are reported publically and impact facility reputation and reimbursement.•At our academic facility, 206 (42%) HO-CDI LabID were “non-true HO-CDI” but positive tests with no significant diarrhea, recent laxative, or delayed testing where diarrhea was present on admission.•Facilities' understanding of proportion of HO-CDI that represent inappropriate or delayed tests will help target improvement strategies.•Diagnostic stewardship has an important role in ensuring appropriate Clostridium difficile testing. We describe the proportion of health care facility-onset Clostridium difficile infection (HO-CDI) National Healthcare Safety Network laboratory-identified events at our facility that were deemed nontrue HO-CDIs. Reasons included testing in a patient without significant diarrhea or with recent laxative use, or delayed testing. Standardized infection ratios using only true HO-CDI in the numerator were improved compared with publically reported standardized infection ratios. A prioritization matrix identifies which clinical services could benefit most from directed diagnostic stewardship interventions.