481. Implementation of a Prospective, Pharmacist-Driven Clostridium difficile PCR Pre-Authorization Process to Optimize Appropriate Testing

BACKGROUND: Since the implementation of more sensitive molecular diagnostics such as the Clostridium difficile PCR assay, hospitals have reported 50–100% increases in C. difficile infection (CDI) rates. METHODS: This single-center, quasi-experimental study assessed appropriateness of C. difficile PCR testing pre- and post-implementation of a prospective, pharmacist-led, pre-authorization process. The antimicrobial stewardship team prospectively reviewed all adult CDI-PCR cases sent to the laboratory prior to specimen processing twice daily, 7 days a week to assess for clinical appropriateness based on guideline criteria. Bone marrow transplant and pediatric patients were excluded. If a patient lacked appropriate CDI clinical criteria, the provider was contacted to discontinue the PCR. CDI-PCR appropriateness was assessed for all patients with a CDI-PCR during the preceding year as a retrospective, comparative cohort. The primary objective was to assess appropriateness of the CDI-PCR pre- and postintervention. Secondary objectives included intervention sensitivity, specificity, safety, total CDI-PCRs processed, and protocol adherence. RESULTS: A total of 714 patients were included (n = 360, preintervention; n = 354, postintervention). There were significantly more hospital-onset CDI cases and antimicrobial use within the past 30 days in the preintervention group [(248 vs. 133, respectively; P < 0.001) and (277 vs. 197, respectively; P < 0.0001)]. Appropriateness of the CDI-PCR significantly improved postintervention [n = 138 (38.3%) vs. n = 209 (59.1%), respectively; P < 0.001]. Prospective pharmacist intervention was required for 146 inappropriate CDI-PCRs resulting in 79 discontinued and 66 processed CDI-PCRs (n = 1 positive; n = 65 negative). No patient with a cancelled CDI-PCR required additional testing or escalation of care. When compared with the preintervention, the CDI-PCRs with pharmacist intervention demonstrated a significant increase in the sensitivity (64.7% vs. 98%; P < 0.0001) and decrease in specificity (66% vs. 48.3%; P = 0.015) with an improved NPV (91.9% vs. 99.3%; P = 0.035) and PPV (23.9% to 24.6%; P = 0.869). CONCLUSION: Implementation of a pharmacist-led prospective CDI-PCR review improved PCR appropriateness and had no adverse clinical consequences although the PPV criteria remain low. DISCLOSURES: All authors: No reported disclosures.