Background It is unclear if bronchopulmonary dysplasia (BPD) is independently associated with reduced expiratory airflow at school age.
Objective To determine the independent associations of moderate–severe BPD, mild BPD, gestational age and birth weight z-score with expiratory airflow in children born extremely preterm (EP; <28 weeks’ gestation).
Methods All EP survivors born in Victoria, Australia, in three eras (1991–1992, n=225; 1997, n=151; and 2005, n=170) were recruited at birth and 418/546 (77%) had valid spirometry data at 8 years. BPD was classified as moderate–severe (oxygen requirement at 36 weeks’ postmenstrual age), or mild (oxygen >28 days but not at 36 weeks’ postmenstrual age). Expiratory airflow variables, including the forced expired volume in 1 s (FEV1), were measured and values converted to z-scores.
Results Compared with no BPD (n=94), moderate–severe BPD (n=193) was associated with a substantial reduction in expiratory airflow (eg, zFEV1 mean difference −0.69, 95% CI −0.97 to –0.41; p<0.001), but mild BPD (n=131) was not (zFEV1 mean difference 0.01, 95% CI −0.28 to 0.31; p=0.93). On multivariable analysis, moderate–severe BPD remained strongly associated with reduced airflow (zFEV1 mean difference −0.63, 95% CI −0.92 to –0.33; p<0.001), but mild BPD (zFEV1 mean difference 0.04, 95% CI −0.26 to 0.34; p=0.27), gestational age (zFEV1 0.06 mean increase per week, 95% CI −0.05 to 0.17; p=0.29) and birth weight z-score (zFEV1 0.07 mean increase per SD, 95% CI −0.06 to 0.20; p=0.28) were not.
Conclusions In children born EP, moderate–severe BPD, but not mild BPD was independently associated with reduced expiratory airflow at 8 years.
- Paediatric Lung Disaese
- Clinical Epidemiology
Data availability statement
All data relevant to the study are included in the article or uploaded as supplemental information.
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Collaborators The Victorian Infant Collaborative Study Group: Peter Anderson, PhD: Turner Institute for Brain and Mental Health, Monash University, Clayton, Australia; Victorian Infant Brain Studies, Murdoch Children’s Research Institute, Melbourne, Australia. Alice Burnett, PhD: Victorian Infant Brain Studies, Murdoch Children’s Research Institute, Melbourne, Australia; Premature Infant Follow-up Program, Royal Women’s Hospital, Melbourne, Australia; Department of Paediatrics, University of Melbourne, Melbourne, Australia; Department of Neonatal Medicine, Royal Children’s Hospital, Melbourne, Australia. Margaret P. Charlton, MEd Psych: Newborn Services, Monash Medical Centre, Melbourne, Australia. Noni Davis, FRACP: Premature Infant Follow-up Program, Royal Women’s Hospital, Melbourne, Australia. Julianne Duff, FRACP: Premature Infant Follow-up Program, Royal Women’s Hospital, Melbourne, Australia; Neonatal Services, Mercy Hospital for Women, Melbourne, Australia. Katherine J Lee, PhD: Clinical Epidemiology and Biostatistics, Murdoch Children’s Research Institute, Melbourne, Australia. Marion McDonald, RN Premature Infant Follow-up Program, Royal Women’s Hospital, Melbourne, Australia. Gillian Opie, FRACP: Neonatal Services, Mercy Hospital for Women, Melbourne, Australia. Amanda Williamson, BSc: Neonatal Services, Mercy Hospital for Women, Melbourne, Australia.
Contributors LWD and JC conceived and designed the study. LWD and JC were involved in identifying or assessing the children and in data collection. LWD, SR and JC were all involved in the data analysis or interpretation. LWD drafted the manuscript. All authors were involved in revising the manuscript and approved the final submitted version, and all agree to be accountable for all aspects of the work. LWD accepts full responsibility for the work and/or the conduct of the study, had access to the data, and controlled the decision to publish.
Funding Supported by grants from the National Health and Medical Research Council of Australia (Centre of Clinical Research Excellence #546519; Centre of Research Excellence #1060733 and 1153176; Career Development Fellowship #1141354 to JC), and the Victorian Government’s Operational Infrastructure Support Program.
Disclaimer The funding sources had no role in the study design; in the collection, analysis and interpretation of data; in the writing of the report; or in the decision to submit the paper for publication.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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