Temporal Trends and Factors Associated with Oseltamivir Administration in Hospitalized Children with Influenza 2007-2020

Background: Since 2007, pediatric clinical practice guidelines have recommended the administration of oseltamivir for all hospitalized children with influenza. However, the evidence upon which this recommendation is based is limited and variation in use has been described. Our objectives were to describe temporal trends and determine independent factors associated with oseltamivir administration in US children hospitalized with a diagnosis of influenza since 2007.

Methods: We performed a retrospective cohort study of all children under 18 years of age who were admitted to a participating hospital in the Pediatric Heath Information System (PHIS) with a diagnosis of influenza between October 2007 and March 2020. We described temporal trends as well as institutional and geographical variations in use of oseltamivir. We used generalized linear mixed effects models to determine independent factors associated with oseltamivir utilization adjusted for site and influenza season. Variables included in the models were determined a priori and included demographic characteristics, presence of severe disease at presentation (defined as presence of any of the following on hospital day 0 or 1: ICU admission, positive pressure ventilation, or central line) as well as presence of known high risk conditions such as medical complexity and history of asthma.

Results: 70,473 patients from 36 hospitals were included in the study. Overall, 47,071 (66.8%) patients were treated with oseltamivir, with use increasing over the study period, reaching a maximum of 78% in the 2017-2018 season (Figure 1). Institutions ranged from 43% to 80% overall use during the study period, with interquartile ranges (IQR) of hospital level use for each year shown in Figure 1. Geographic regions tended to follow the overall trend, differing by 3-25% depending on the year, with overall proportions of 66.9%, 64.5%, 64.2%, and 71.1% in the Midwest, Northeast, South, and West regions respectively. Independent patient factors associated with increased oseltamivir administration included age over 5, non-white race, public insurance, presence of medical complexity, history of asthma, and severe illness at presentation, with odds ratios shown in Table 1.

Conclusion: Oseltamivir use has increased over time but varies by institution and despite guidelines is still not administered in over 20% of children hospitalized with influenza. Critically ill children and those with high risk conditions other than age were more likely to receive oseltamivir. Young children were less likely to be treated with oseltamivir.