Association between the Use of Antibiotics, Antivirals, and Hospitalizations among Patients with Laboratory Confirmed Influenza

BACKGROUND: Clinicians may prescribe antibiotics to influenza patients at high risk for bacterial complications. We explored the association between antibiotics, antivirals and hospitalization among influenza patients. METHODS: A retrospective cohort study of confirmed influenza patients with encounters during January 2011-January 2019 was conducted using data from the VA Informatics and Computing Infrastructure (VINCI). We compared inpatient hospitalizations (all-cause and respiratory) within 30 days of influenza diagnosis between four patient cohorts: (1) no treatment (n=4,228); 2) antibiotic only (n=671); 3) antiviral only (n=6,492); and 4) antibiotic + antiviral (n=1,415). We estimate relative risk for hospitalization using Poisson generalized linear model and robust standard errors. RESULTS: Among 12,806 influenza cases, most were white males with a mean age between 57 and 60 years. Those with antivirals only, antibiotic + antiviral, and antibiotics only all have a statistically significant lower risk of all-cause and respiratory hospitalization compared to those without treatment. Comparing the antibiotic + antiviral cohort to those who were prescribed an antiviral alone, there was 47% lower risk for respiratory hospitalization (RR=0.53, 95% CI=0.31-0.94) and no other statistical differences were detected. CONCLUSIONS: Those prescribed an antiviral, antibiotic, or both had a lower risk of hospitalization within 30 days compared to those without therapy. Furthermore, intervention with both an antibiotic and antiviral had a lower risk of respiratory hospitalization within 30 days compared to those with an antiviral alone. Importantly, the absolute magnitude of decreased risk with antibiotic + antiviral therapy is small and must be interpreted within the context of the overall risk of antibiotic usage.