Chest. 2022 Feb 5:S0012-3692(22)00221-5. doi: 10.1016/j.chest.2022.01.053. Online ahead of print.
BACKGROUND: Influenza is a leading cause of community-acquired pneumonia (CAP) and influenza test results can direct therapy. However, among adults hospitalized with CAP, little is known about frequency and timing of influenza testing, treatment and their associations with outcomes.
RESEARCH QUESTION: In patients with pneumonia is testing for influenza associated with antiviral treatment and shorter antibiotic courses, and is early treatment associated with better clinical outcomes?
STUDY DESIGN AND METHODS: We included adults admitted with pneumonia in 2010-2015 to 179 US hospitals contributing to the Premier database. We assessed influenza testing and compared antimicrobial utilization and outcomes of test positive, negative and untested patients. We studied associations of early antiviral treatment (oseltamivir) with 14-day in-hospital mortality, hospital length-of-stay (LOS) and cost.
RESULTS: Among 166,268 CAP patients, 38,703 (23.3%) were tested for influenza, of whom 11.5% tested positive. Testing increased from 15.4% to 35.6% from 2010-2015 and was 28.9% during flu season (Oct-May) vs. 8.2% in June-September. Patients testing positive for influenza received antivirals more often and antibacterials less often and for shorter courses than patients testing negative (5.3 vs 6.4 days, p<0.001). Influenza-positive patients receiving oseltamivir on hospital day 1 (n=2,585) experienced lower 14-day in-hospital mortality (adjusted odds ratio 0.75, 95% CI 0.59-0.96) , lower costs (adjusted ratio of means 0.88, 95% CI 0.81-0.95) and shorter LOS (adjusted ratio of means 0.88, 95% CI 0.84-0.93) vs. patients receiving oseltamivir later or not at all (n=1,742).
INTERPRETATION: Even during flu season, most patients with CAP in our study went untested for influenza. A positive influenza test was associated with antiviral treatment and early treatment was associated with lower mortality, suggesting more widespread testing might improve patient outcomes.