Antimicrobial prescribing after rapid influenza PCR implementation in the emergency department.

INTRO: Influenza shares common symptoms with bacterial pneumonia, which may result in unnecessary antibiotic prescriptions in the emergency department (ED) when the diagnosis is unknown. Rapid influenza polymerase chain reaction (PCR) tests have reduced turnaround times compared to standard multiplex PCR respiratory panels allowing for earlier diagnosis, which may improve antimicrobial stewardship outcomes in the ED. This study aims to compare antibiotic and antiviral use before and after deployment of the rapid influenza PCR in the ED.

METHODS: This single-center, retrospective, cohort study included pediatric and adult patients discharged from the ED with a positive influenza test using a standard multiplex PCR respiratory panel (January 2017 - July 2019) or rapid PCR (July 2019 - February 2020). The primary endpoint was number of antibiotic prescriptions pre- and post-implementation of the rapid influenza PCR in the ED. Secondary endpoints included number of antiviral prescriptions, duration of antimicrobial therapy, test turnaround time, ED length of stay, 30-day readmission, and adverse events. A multivariable logistic regression evaluated patient factors associated with antimicrobial prescribing.

RESULTS: A total of 620 positive influenza results were identified with 280 patients (standard multiplex PCR = 33; rapid PCR = 247) meeting inclusion criteria. Patients were less likely to be prescribed antibiotics (39.4% vs 8.9%, OR 0.15, 95% CI 0.067-0.34) and more likely to be prescribed antivirals (24.2% vs 61.1%, OR 4.92, 95% CI 2.13-11.34) with the rapid influenza PCR. Rapid influenza PCR significantly reduced ED length of stay (4.9 vs 3.4 h, p < 0.01) and test turnaround time (27 h vs 3.5 h, p < 0.01). Patients at high risk for complications associated with influenza were more likely to be prescribed antiviral therapy (22.7% vs 67.8%, OR 7.16, 95% CI 2.52-20.40). Based on the regression analysis conducted, asthma, (OR 3.5, 95% CI 1.48-8.26), immunosuppression (OR 9.6, 95% CI 1.18-78.2), and age <5 years old (OR 3.1, 95% CI 1.80-5.45) were predictors of antiviral prescribing.

CONCLUSION: Implementation of a rapid influenza PCR in the ED reduced antibiotic use and optimized antiviral therapy for patients with influenza including those at higher risk of complications.