Diagnostic stewardship of C. difficile testing: a quasi-experimental antimicrobial stewardship study

Objective: We evaluated whether a diagnostic stewardship initiative consisting of ASP preauthorization paired with education could reduce false-positive hospital-onset (HO) Clostridioides difficile infection (CDI). Design: Single center, quasi-experimental study. Setting: Tertiary academic medical center in Chicago, Illinois. Patients: Adult inpatients were included in the intervention if they were admitted between October 1, 2016, and April 30, 2018, and were eligible for C. difficile preauthorization review. Patients admitted to the stem cell transplant (SCT) unit were not included in the intervention and were therefore considered a contemporaneous noninterventional control group. Intervention: The intervention consisted of requiring prescriber attestation that diarrhea has met CDI clinical criteria, ASP preauthorization, and verbal clinician feedback. Data were compared 33 months before and 19 months after implementation. Facility-wide HO-CDI incidence rates (IR) per 10,000 patient days (PD) and standardized infection ratios (SIR) were extracted from hospital infection prevention reports. Results: During the entire 52 month period, the mean facility-wide HO-CDI-IR was 7.8 per 10,000 PD and the SIR was 0.9 overall. The mean +/- SD HO-CDI-IR (8.5 +/- 2.0 vs 6.5 +/- 2.3; P < .001) and SIR (0.97 +/- 0.23 vs 0.78 +/- 0.26; P = .015) decreased from baseline during the intervention. Segmented regression models identified significant decreases in HO-CDI-IR (P-step = .06; P-trend = .008) and SIR (P-step = .1; P-trend = .017) trends concurrent with decreases in oral vancomycin (P-step < .001; P-trend < .001). HO-CDI-IR within a noninterventional control unit did not change (P-step = .125; P-trend = .115). Conclusions: A multidisciplinary, multifaceted intervention leveraging clinician education and feedback reduced the HO-CDI-IR and the SIR in select populations. Institutions may consider interventions like ours to reduce false-positive C. difficile NAAT tests.