Presented at the Neonatal Society 2009 Autumn Meeting.
Hoo AF1, Gupta A1, Lum S1, Costeloe KL2, Huertas-Ceballos A3, Stocks J1
1 Portex Respiratory Unit, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH
2 Neonatal Unit, Homerton University Hospital NHS Foundation Trust, London E9 6SR
3 Neonatal Unit, University College London Hospital, London NW1 2BU
Background: Survival of infants born extremely preterm is associated with a high prevalence of bronchopulmonary dysplasia (BPD) and subsequent respiratory morbidity. Diminished lung function in infancy may have life long effects on respiratory health (1).
Aim: To examine the associations between lung function results at 1-year of age between infants born extremely preterm (<26 completed weeks gestational age, GA) with those from more mature preterm (>27-36w GA) and full-term (>37w GA) infants.
Methods: The EPICure 2 study recruited all survivors born <26 completed weeks gestational age in England during 2006 (2). Respiratory follow-up using the Raised Volume Technique was undertaken in a subset of these babies (EPI), together with preterm (PTC) and healthy term controls (TC) at 1 year corrected postnatal age. Results were expressed as Z-scores based on local controls to adjust for age, sex and body size. The study was approved by the Institutional Research Ethics Committees.
Results: Measurements were obtained in 42 EPI, 38 PTC and 44 TC (mean GA: 25.7, 34.6 and 39.6w, respectively). The groups were well matched for sex and age at test but EPI children remained significantly lighter and shorter. On univariate analysis, z-scores for forced expiratory volumes and flows were significantly lower in the EPI group than in either the PTC or TC children. On multivariate analysis of lung function z-scores, gestational age was significantly associated with all lung function outcomes and, amongst the EPI and PTC groups but not term controls, forced expiratory volume at 0.5s (FEV0.5) was lower in boys than girls. After adjusting for age, sex and length, forced expired flows and volumes were significantly lower in infants of non-white mothers.
Conclusion: Despite improved survival of extremely preterm infants, abnormalities of lung function persist to 1 year of age. Our findings suggest that preterm birth appears to have a greater impact on lung development in boys than girls, and in those who are most immature at delivery. The observed ethnic differences in lung function may reflect differences in body proportions, as observed in older subjects, rather than a deficit per se, but emphasise the importance of taking ethnic background into account when interpreting infant lung function results.
Acknowledgements: Funded by the British Lung Foundation and Medical Research Council.
References
1. Stern DA et al, Lancet 2007;758-764
2. Costeloe KL et al, Arch Dis Child, Nov2008;93:espr13