RSV-Passive Immunization Reduces Antimicrobial Consumption During RSV Infection in Infants and Young Children -5 Years in Japan

OBJECTIVES: Respiratory infections are the main causes for hospitalization in children and a common reason for the initiation of antibiotic treatment. The primary objective of this study was to describe antimicrobials use in Japan among infants and young children<5 years of age infected with respiratory syncytial virus (RSV) and assess if passive immunization results in a decrease of antimicrobials consumption.

METHODS: The Japanese Medical Center Database was used to retrospectively identify RSV and controls without RSV (February 1, 2011- January 31, 2016 followed through December 31, 2017). Based on ICD-10 diagnosis codes, each antibiotic prescription was mapped to a body system and possible intent for use. Incidence rate and cost ratio estimates from Poisson and gamma multivariate regression models measured the effect of palivizumab prophylaxis on all-cause and respiratory-related antimicrobial consumption and costs (flagged as appropriate or not).

RESULTS:

We identified 113 529 children of whom 17,022 (15%) were ever diagnosed with RSV. When examining only claims with RSV diagnosis linked to antimicrobial use records, the overall inappropriate use of antimicrobials was 33.9% (51.1% when only respiratory-related indications were used as possible justifiable use). This was largely driven by inappropriate use of aminoglycosides injection 56.2% (60.0%), cephalosporins injection 37.5% (57.7%), oral macrolides 39.3% (53.3%), penicillins injection 51.6% (67.6%). Among late premature and term children, all-cause antimicrobials use was lower with full prophylaxis compared to those without (18% lower cost and 8% lower days on antimicrobials at any time; for inappropriate use - 10% and 8% lower, respectively). The expected reduction in antimicrobials exposure due to palivizumab immunization in Japan was ¥54.7 million and 212,600 fewer days, calculated over the 12 months of follow-up since birth.

CONCLUSIONS: Study findings are important in supporting medical decision-making regarding the selection of antiviral treatments, restriction of antibiotic therapy, and infection control strategies for RSV.