Influenza is a seasonal respiratory virus of significant public health importance. Each year an estimated 3 to 5 million cases of severe influenza illnesses occur globally, and between 250,000 and 500,000 people will die as a result of their infection. Neonates and infants under 6 months are at particular risk of severe infection (termed complicated influenza), and, given the immaturity of the immune system in these patients, there are no licensed influenza vaccines and treatment options are limited.
Intravenous (IV) zanamivir, which provides an additional treatment option for critically ill influenza patients, was approved for use in Europe in 2019. We are currently conducting a clinical study (not in CPRD; NCT04494412) to evaluate the safety and tolerability of IV zanamivir in hospitalized neonates and infants under 6 months of age with confirmed complicated influenza infection. Recruitment of neonates into this study is challenging; to inform sample size adjustment going forward we need reliable estimates of influenza hospitalization in this age group.
The proposed feasibility study (using CPRD data) will help us understand the levels of hospital admission for influenza among young children, which will inform how our ongoing (clinical) study can be modified to ensure success. The outcomes of the ongoing clinical safety study will in turn improve patient care in England by informing on the most appropriate treatment options for complicated influenza in neonates and infants.
This feasibility study aims to generate counts of patients admitted to the hospital with influenza in England during influenza seasons 2017/18, 2018/19, and 2019/20. Influenza seasons will be defined as: 1 October 2017 – 15 May 2018, 1 October 2018 – 15 May 2019, 1 October 2019 – 15 May 2020.
The denominator will be patients registered, and with continuous participation, in CPRD and who are eligible for HES linkage. The numerator will be patients hospitalized with influenza in HES data. Rate of hospitalization, stratified by age group, will be calculated as the number of influenza hospitalizations per 100,000 person years per influenza season.
Counts for the numerators and denominators will be reported in total and stratified by age groups (≤1mo; 2mo-6mo; 7-12mo; 0-1yrs; 2-11yrs; 12-17yrs; 18-49yrs; 50-64yrs; 65+yrs), and separately for each influenza season.
The data requested from HES to determine counts of hospitalizations are: (1) influenza ICD-10 admission code and associated event date, (2) Patient ID.
No formal statistical testing will be undertaken.
Our ongoing clinical study evaluates the safety and tolerability of IV zanamivir in hospitalized neonates and infants under 6 months of age with complicated influenza infection. The proposed feasibility study (using CPRD-HES linked data) will help us understand the levels of hospital admission for influenza among young children, which will inform how our ongoing (clinical) study can be modified to ensure success. Study outcomes of the proposed feasibility study (using CPRD-HES linked data) will be included in any application with an intention to improve clinical practice guidelines on influenza hospitalizations among young children, indirectly improving patient care in England.
Influenza hospital admission, as defined by a record of an ICD-10 admission code (including sub codes) for influenza (J09*, J10*, J11*).
Rosa Sloot - Chief Investigator - GSK India Global Service Private Limited
Rosa Sloot - Corresponding Applicant - GSK India Global Service Private Limited
Dhirishiya Padmavathy - Collaborator - GSK India Global Service Private Limited
Iain Gillespie - Collaborator - GlaxoSmithKline Research & Development Limited (UK)
Shinyoung Ju - Collaborator - GSK
HES Admitted Patient Care