A Retrospective Cohort Study of the Effect of Rapid Versus Delayed-result Procalcitonin Testing on Antibiotic Use at a Community Hospital

Abstract Background: Procalcitonin is a serum biomarker used to distinguish bacterial infection from viral or noninfectious syndromes. Primary literature shows mixed data on use of procalcitonin for de-escalation of antimicrobials. Delays in test results of send-out procalcitonin assays may result in prolonged antimicrobial durations. It is unknown whether availability of in-house assays may shorten time to antibiotic de-escalation. Aim: This retrospective, cohort study compared antibiotic durations of treatment between groups with a rapid-result versus a delayed send-out, procalcitonin test modality.This study was exempt from Ethics Committee Approval, as determined by the Institutional Review Board at the study site. Methods: Adult hospitalized patients were included if they had at least one procalcitonin test performed during the study period. The primary outcome compared mean duration of antimicrobial therapy between groups receiving a rapid-result procalcitonin test and a delayed-result test. Secondary outcomes included incidence of Clostridiodes difficile infection, mention of procalcitonin testing in the electronic medical record in reference to antimicrobial therapy decision making, and presence of comorbidities which affect procalcitonin levels independent of infection. Results: A total of 350 lab results were analyzed. The duration of antimicrobial treatment between groups was not statistically different with the median duration of treatment in the send-out group being 2.95 days compared to 3.35 in the in-house group, p=0.856. Patient comorbidities with potential to lead to a noninfectious elevation or falsely high level of procalcitonin were common. Conclusion: Use of a rapid-result procalcitonin assay does not reduce hospital antimicrobial therapy duration as compared with send-out testing.