Respiratory health up to school age following extremely preterm birth

The prevalence of bronchopulmonary dysplasia (BPD) appears to have risen with the increasing survival of extremely preterm infants, in whom the incidence of BPD is highest. However, despite increasing survival at extremely low gestational ages, there is little gestational age-based information regarding long-term outcomes. In particular, whether BPD is associated with worse developmental outcomes over and above the disability associated with preterm birth is still under debate. The EPICure study was conducted prospectively on all babies born between 20 weeks and 25⁺⁶ weeks gestational age in the United Kingdom and Ireland over a 10- month period beginning in March 1995. The results of the EPICure study strongly suggested that BPD and its treatment may represent key factors associated to neonatal illness and outcome in extremely preterm infants, with important long-term sequelae on psychomotor and mental development.
The investigators involved in the EPICure study have recently conducted a follow-up analysis of this trial describing longitudinal respiratory health in the children originally enrolled, from birth up to 6 years. In total, 308 babies born at ≤25 weeks' gestation in 1995 were followed up at 30 months and 6 years of age. Respiratory outcome was evaluated using clinical assessment, parental questionnaire and peak expiratory flow (PEF) at 6 years.
Results show that 74% of this population received supplemental oxygen at 36 weeks postmenstrual age and 36% were discharged with supplemental oxygen, which continued for a median of 2.5 months. The follow-up at 6 years was available for 236 children. Respiratory symptoms and medication use were more prevalent at 30 months and 6 years in children with BPD (n=163) compared to those without (n=56). Moreover, children without BPD had a consistently higher prevalence of poor respiratory health than what observed in their classmates. However, it was observed that symptoms, need for hospital admission and medication use declined between 30 months and 6 years. PEF measures were available for 200 children; PEF was lower than in classmates and was lowest in children discharged home with oxygen and in those with BPD. Statistical analysis of risk factors suggested that gestational age, BPD and maternal smoking at home and during pregnancy were independent predictors for symptoms, but BPD was the only independent risk factor associated with low PEF.
Taken together, these results suggest that long-term respiratory outcomes are poor over the first 6 years for extremely premature babies, despite some improvements between 30 months and 6 years. Poor respiratory status is exacerbated by mothers smoking at home and during pregnancy, while BPD seems to affect PEF. Longer follow-up studies are required to fully understand the sequelae of BPD in adolescence and adult life.

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