Clinical Practice Patterns and Risk Factors for Severe Conditions in Pediatric Hospitalizations With Respiratory Syncytial Virus in Japan: A Nationwide Analyses (2018-2022)

Background:Respiratory syncytial virus (RSV) represents a global health challenge, especially among younger children. While the disease burden in Japan has been preliminarily quantified, there remains a lack of comprehensive understanding regarding treatment patterns and the influence of known risk factors at a national scale.Materials and Methods:We conducted a retrospective cohort study consisting of 50,482 children under 5 years hospitalized with RSV infections during 2018-2022 using the Medical Data Vision database. We investigated trends in patient characteristics, health resource use, treatment patterns, and laboratory data. Additionally, multivariable modified Poisson regression models were used to investigate the risk factors associated with severe conditions.Results:We observed an increasing trend in the inpatient healthcare costs and decreasing trends in the use of antibiotics, bronchodilators, systemic corticosteroids and other symptomatic medications from 2018 to 2022. Risk factors associated with severe RSV infections were children less than 1 year (risk ratio, 2.90; 95% CI: 2.53-3.32) and the number of complex chronic diseases (risk ratio for 1 disease, 2.68; 95% CI: 2.34-3.06: risk ratio for 2 or more diseases, 6.91; 95% CI: 5.81-8.21). Annual inpatient healthcare costs for RSV infections were estimated at 11-14 billion Japanese Yen for younger children.Conclusions:Our study observed the changes in practice patterns and health resource use for children hospitalized with RSV infections and identified risk factors associated with severe conditions. These findings provide insights for policymakers and clinicians aiming to devise strategies for further improving clinical practices, including newly developed vaccines and single-dose long-acting monoclonal antibodies.