Patient Outcomes With Prevented vs Negative Clostridioides difficile Tests Using a Computerized Clinical Decision Support Tool

BACKGROUND: Overtesting and overdiagnosis of Clostridioides difficile infection are suspected to be common. Reducing inappropriate testing through interventions designed to promote evidence-based diagnostic testing (ie, diagnostic stewardship) may improve C. difficile test utilization. However, the safety of these interventions is not well understood despite the potential risk for missed or delayed diagnoses. METHODS: This retrospective case–control study examined the outcomes of patients admitted to the University of Virginia Medical Center following introduction of a computerized clinical decision support tool without hard-stops designed to reduce inappropriate tests. Outcomes were compared between patients with a prevented C. difficile nucleic acid amplification test and those with a negative result. Chart reviews were performed for patients with a subsequent positive within 7 days, as well as those patients who received C. difficile–active antibiotics after implementation of the computerized clinical decision support tool. RESULTS: Multivariate analysis of 637 cases (490 negative, 147 prevented) showed that a prevented test was not significantly associated with the primary composite outcome (inpatient mortality or intensive care unit transfer) compared with a negative test (adjusted odds ratio, 0.912; P = .747). Fifty-four of 147 (37%) prevented tests were followed by a completed test within 7 days; 11 of these results were positive, resulting in a potential delay in diagnosis. Individual case reviews found that either clinical changes warranted the delay in testing or no adverse events occurred attributable to C. difficile infection. C. difficile treatment without a positive test was not identified. CONCLUSIONS: Diagnostic stewardship of C. difficile testing using computerized clinical decision support may be both safe and effective for reducing inappropriate inpatient testing.