Background Inappropriate Clostridioides difficile testing is common in the hospital setting, leading to potential overdiagnosis of infection when single-step nucleic acid amplification testing is used. The potential role of infectious diseases specialists in enforcing appropriate C. difficile testing is unclear. Methods At a single 697-bed academic hospital, we performed a retrospective study from March 1, 2012 to December 31, 2019 comparing hospital onset C. difficile infection rates (HO-CDI) during three consecutive time periods: baseline 1 (37 months, no decision support), baseline 2 (32 months, computer decision support), and intervention period (25 months, mandatory infectious diseases specialist approval for all C. difficile testing on hospital day 4 or later). We used a discontinuous growth model to assess the impact of the intervention on HO-CDI rates. Results During the study period, we evaluated C. difficile infections across 331,180 admission and 1,172,015 patient days. During the intervention period, a median of one HO-CDI test approval request per day (range, 0 to 6 alerts/day) was observed; adherence by providers with obtaining approval was 85%. The HO-CDI rate was 10.2, 10.4, and 4.3 events per 10,000 patient days for each consecutive time period, respectively. In adjusted analysis, the HO-CDI rate did not differ significantly between the two baseline periods (P = .14) but did differ between the baseline 2 period and intervention period (P < .001). Conclusions An infectious disease-led C. difficile testing approval process was feasible and associated with a >50% decrease in HO-CDI rates, due to enforcement of appropriate testing.

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