Introduction and objective: Diagnostic testing for Clostridioides difficile infection (CDI) by nucleic acid amplification test (NAAT) cannot distinguish between colonization and infection. A positive NAAT may therefore represent a false positive for infection, since diarrhea due to various aetiologies may occur in hospitalized patients. Our objective was to help answer the question: "does this medical inpatient with diarrhea have CDI?"
Design: We conducted a retrospective cohort study (n = 248) on the Clinical Teaching Units of the Royal Victoria Hospital (Montréal, Canada). Patients were included if they had a NAAT between January 2014 and September 2015 and their admission diagnosis was not CDI. CDI cases and non-CDI cases were compared, and independent predictors of CDI were determined by logistic regression.
Results: Several factors were independently associated with CDI, including: hemodialysis (OR: 13.5, 95% CI: 2.85-63.8), atrial fibrillation (OR: 3.70, 95% CI: 1.52-9.01), whether the patient received empiric treatment (OR: 3.01, 95% CI: 1.04-8.68), systemic antibiotic therapy prior to testing (OR: 4.23, 95% CI: 1.71-10.5), previous positive NAAT (OR: 3.70, 95% CI: 1.41-9.72), and a leukocyte count of 11x109/L or higher (OR: 3.43, 95% CI: 1.42-8.26). The area under the curve was 0.80.
Conclusion: For patients presenting with hospital-onset diarrhea, various parameters can help differentiate between CDI and other causes. A clinical prediction calculator derived from our cohort (http://individual.utoronto.ca/leet/cdiff.html) might assist clinicians in estimating the risk of CDI for inpatients; those with low pre-test probability may not require immediate testing, treatment, nor prolonged isolation.