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 people with influenza. Methods. A retrospective cohort study of patients with confirmed influenza with encounters during January 2011-January 2019 was conducted using data from the Veterans Affairs Informatics and Computing Infrastructure (VINCI). We compared inpatient hospitalizations (all-cause and respiratory) within 30 days of influenza diagnosis between 4 patient cohorts: (1) no treatment (n = 4228); (2) antibiotic only (n = 671); (3) antiviral only (n = 6492); and (4) antibiotic plus antiviral (n = 1415). We estimated relative risk for hospitalization using Poisson generalized linear model and robust standard errors. Results. Among 12 806 influenza cases, most were white men (mean age, 57-60 years). Those with antivirals only, antibiotic plus antiviral, and antibiotics only all had a statistically significant lower risk of all-cause and respiratory hospitalization compared to those without treatment. Comparing the antibiotic plus antiviral cohort to those who were prescribed an antiviral alone, there was a 47% lower risk for respiratory hospitalization (relative risk, 0.53 [95% confidence interval, .31-.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 plus antiviral therapy is small and must be interpreted within the context of the overall risk of antibiotic usage.