Mortality and severe morbidity of very preterm infants: comparison of two French cohort studies

Background In Reunion Island, a French overseas department, the burden of preterm birth and perinatal mortality exceed those observed in mainland France, despite similar access to standard perinatal care. The purpose of the study was to compare the outcome of two cohorts of NICU-admitted very preterm infants born between 24 and 31 weeks of gestation (WG): the registry-based OGP (Observatoire de la Grande Prematurite, Reunion Island, 2008-2013) cohort, and the nationwide EPIPAGE-2 (mainland France, 2011) observational cohort. Methods The primary outcome was adverse neonatal outcomes defined as a composite indicator of in-hospital mortality or any of three following severe morbidities: bronchopulmonary dysplasia (BPD), necrotising enterocolitis, or severe neurological injury (periventricular leukomalacia or grade III-IV intraventricular haemorrhages). Logistic regression modelling adjusting for confounders was performed. Results A total of 1272 very preterm infants from the Reunionese OGP cohort and 3669 peers from the mainland EPIPAGE-2 cohort were compared. Adverse neonatal outcomes were more likely observed in the OGP cohort (32.6% versus 26.6%, p < 0.001), as result of both increased in-hospital mortality across all gestational age strata and increased BPD among the survivors of the 29-31 WG stratum. After adjusting for gestational age, gender and multiple perinatal factors, the risk of adverse neonatal outcomes was higher in the OGP cohort than in the EPIPAGE-2 cohort across all gestational age strata. Conclusions Despite similar guidelines for standard perinatal care, very preterm infants born in Reunion Island have a higher risk for death or severe morbidity compared with those born in mainland France.