Increasing airway obstruction through life following bronchopulmonary dysplasia: a meta-analysis

BACKGROUND: Few studies exist investigating lung function trajectories of those born preterm; however growing evidence suggests some individuals experience increasing airway obstruction throughout life. Here we use the studies identified in a recent systematic review to provide the first meta-analysis investigating the impact of preterm birth on airway obstruction measured by the forced expiratory volume in 1 s (FEV(1)) to forced vital capacity (FVC) ratio. METHODS: Cohorts were included for analysis if they reported FEV(1)/FVC in survivors of preterm birth (<37 weeks’ gestation) and control populations born at term. Meta-analysis was performed using a random effect model, expressed as standardised mean difference (SMD). Meta-regression was conducted using age and birth year as moderators. RESULTS: 55 cohorts were eligible, 35 of which defined groups with bronchopulmonary dysplasia (BPD). Compared to control populations born at term, lower values of FEV(1)/FVC were seen in all individuals born preterm (SMD −0.56), with greater differences seen in those with BPD (SMD −0.87) than those without BPD (SMD −0.45). Meta-regression identified age as a significant predictor of FEV(1)/FVC in those with BPD with the FEV(1)/FVC ratio moving −0.04 sds away from the term control population for every year of increased age. CONCLUSIONS: Survivors of preterm birth have significantly increased airway obstruction compared to those born at term with larger differences in those with BPD. Increased age is associated with a decline in FEV(1)/FVC values suggesting increased airway obstruction over the life course.