Risk of neurodevelopmental impairment for outborn extremely preterm infants in an Australian regional network

Objective: To compare neurodevelopmental outcomes at 2-3 years in extremely premature outborn and inborn infants.Design: Population-based retrospective cohort study.Setting: Geographically defined area of New South Wales (NSW) and the Australian Capital Territory (ACT) served by a network of 10 neonatal intensive care units (NICUs).Patients: All premature infants <29 weeks gestation born between 1998 and 2004 in the setting.Intervention: At 2-3 years, corrected age, 1473 children were assessed with either the Griffiths Mental Developmental Scales (GMDS) or the Bayley Scales of Infant Development (BSID-II).Main outcome measure: Moderate/severe functional disability (FD) defined as: developmental delay (GMDS general quotient (GQ) or BSID-II mental developmental index (MDI)) >2 standard deviations (SD) below the mean; cerebral palsy (CP) requiring aids; sensorineural or conductive deafness (requiring amplification); or bilateral blindness (visual acuity <6/60 in better eye).Results: At 2-3 years, moderate/severe functional disability does not appear to be significantly different between outborn and inborn infants (adjusted OR 0.782; 95% CI 0.424-1.443). However, there were a significant number of outborn infants lost to follow up (23.3% versus 42.9%).Conclusion: In this cohort, at 2-3 years follow up neurodevelopmental outcome does not appear to be significantly different between outborn and inborn infants. These results should be interpreted with caution given the limitation of this study.