Background Bronchiolitis causes significant infant morbidity worldwide from hospital admissions. However, studies quantifying the subsequent respiratory burden in children under 5 years are lacking.
Objective To estimate the risk of subsequent respiratory hospital admissions in children under 5 years in England following bronchiolitis admission in infancy.
Design Retrospective population-based birth cohort study.
Setting Public hospitals in England.
Patients We constructed a birth cohort of 613 377 infants born between 1 April 2007 and 31 March 2008, followed up until aged 5 years by linking Hospital Episode Statistics admissions data.
Methods We compared the risk of respiratory hospital admission due to asthma, wheezing and lower and upper respiratory tract infections (LRTI and URTI) in infants who had been admitted for bronchiolitis with those who had not, using Cox proportional hazard regression. We adjusted hazard ratios (HR) for known respiratory illness risk factors including living in deprived households, being born preterm or with a comorbid condition.
Results We identified 16 288/613 377 infants (2.7%) with at least one admission for bronchiolitis. Of these, 21.7% had a further respiratory hospital admission by age 5 years compared with 8% without a previous bronchiolitis admission (HR (adjusted) 2.82, 95% CI 2.72 to 2.92). The association was greatest for asthma (HR (adjusted) 4.35, 95% CI 4.00 to 4.73) and wheezing admissions (HR (adjusted) 5.02, 95% CI 4.64 to 5.44), but were also significant for URTI and LRTI admissions.
Conclusions Hospital admission for bronchiolitis in infancy is associated with a threefold to fivefold risk of subsequent respiratory hospital admissions from asthma, wheezing and respiratory infections. One in five infants with bronchiolitis hospital admissions will have a subsequent respiratory hospital admission by age 5 years.
- infectious diseases
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Contributors HS contributed to the interpretation of the data, drafted the article, revised it critically and prepared the final version to be published with input from senior author, SS. TW, EC and SS contributed to the conception and design, acquisition of data and analyses and interpretation of the data. SS, TW, EC, AB and CC reviewed the drafted manuscript critically for important intellectual content and gave HS approval of the final version to be published.
Funding SS and Imperial College London are grateful for support from the NW London NIHR Collaboration for Leadership in Applied Health Research and Care and the NIHR School for Public Health Research. CC is supported by a NIHR Career Development fellowship (CDF-2016-09-015). The Dr Foster Unit at Imperial is affiliated with the National Institute of Health Research (NIHR) Imperial Patient Safety Translational Research Centre. The NIHR Imperial Patient Safety Translational Centre is a partnership between the Imperial College Healthcare NHS Trust and Imperial College London. The Dr Foster Unit at Imperial College are grateful for support from the NIHR Biomedical Research Centre funding scheme.
Disclaimer The views expressed in this publication are those of the authors and not necessarily those of the NIHR, the NHS or the Department of Health.
Competing interests HS reports personal fees from StGilesMedical, outside the submitted work; TW and EC have nothing to disclose. AB reports grants from Dr Foster, grants from Medtronic, outside the submitted work; CC has nothing to disclose. SS reports grants from NIHR career development fellowship, during the conduct of the study.
Ethics approval Accessing non-identifiable information for secondary use does not require permission from an NHS Research Ethics Committee (REC) according to NHS Health Research Authority. However, the Department of Primary Care and Public Health at Imperial College University had permission to hold confidential data for this project from the Data Access Advisory Group (DAAG reference: 310112-b), the predecessor group to Independent Group Advising on the Release of Data under Section 251 of the NHS Act 2006 and approval for use in research was granted from the South East Ethics Research Committee.
Provenance and peer review Not commissioned; externally peer reviewed.
Patient consent for publication Not required.