Antibiotic use in children hospitalised for influenza, 2010–2021: the Canadian Immunization Monitoring Program Active (IMPACT)

Purpose To determine characteristics associated with inappropriate antibiotic use amongst children hospitalised for influenza. Methods We performed active surveillance for laboratory-confirmed influenza hospitalizations amongst children ≤ 16 years old at the 12 Canadian Immunization Monitoring Program Active hospitals, from September 2010 to August 2021. Antibiotic use was presumed appropriate if any of the following indications were met: age < 1 month, immunocompromised, hemoglobinopathy, laboratory-confirmed bacterial infection, radiographically confirmed pneumonia, admission to an intensive care unit and mechanical ventilation. Regression analyses were used to identify baseline and clinical characteristics associated with antibiotic use amongst patients without an appropriate indication. Results Amongst 8971 children, 6424 (71.6%) received any antibiotics during their hospitalisation. Amongst the 4429 children without an appropriate indication, 2366 (53.2%) received antibiotics. Antibiotic use amongst children without appropriate indication differed between study centres, ranging from 33.2% to 66.1% (interquartile range [IQR] 50.6–56.3%); it did not change significantly over time ( p -value for trend = 0.28). In multivariable analyses, older age (adjusted odds ratio [aOR] 0.97, 95% confidence interval [CI] 0.96–0.99), presence of any high-risk condition (aOR 0.80, 95% CI 0.70–0.92), influenza virus type B (aOR 0.8, 95% CI 0.70–0.91) and croup (aOR 0.64, 95% CI 0.49–0.83) were associated with less, whilst fever ≥ 38.5 °C (aOR 1.82, 95% CI 1.42–2.35) and hospitalisation duration (aOR 1.12, 95% CI 1.09–1.15) were associated with more inappropriate antibiotic use. Conclusions Over two-third of children hospitalised for influenza received antibiotics, including over half of those without an appropriate indication for antibiotic treatment. Differences amongst study centres suggest the importance of contextual determinants of antibiotic use.