Follow-up of Extremely Preterm Infants; the Long and the Short of It.

The study by Cheong et al, 1 “Changing neurodevelopment at 8 years of children born extremely preterm since the early 1990s” in this issue of Pediatrics, once again reminds us of the challenges and limitations of follow-up studies. The authors have done a commendable job following 3 cohorts (1991 to 1992, 1997, and 2005) of extremely preterm infants from 22 to 27 weeks' gestation to 8 years of age. Although the authors previously had shown that there was no improvement in moderate to severe disability at 8 years between 1991 to 1992 and 1997, 2 their report3 of all 3 cohorts at 2 years of age identified a significant decrease in severe disability (15.4% to 3.7%) and severe developmental delay (14.8% to 3.7%) between 1997 and 2005 attributed to improvements in perinatal interventions. The Bayley Scales of Infant and Toddler Development, Third Edition, 4 however, which was first used with the 2005 cohort, is known to underestimate developmental delay. In addition, Bayley scores are not strong predictors of school-age outcomes.5, 6 The purpose of the current study was to additionally compare neurodevelopmental outcomes of the 3 cohorts at 8 years of age. The strengths of this report include the substantial sample size, comprehensive medical and social environmental data, comparison with term controls, blinded school-age assessments, and 8-year follow-up rates of 93%, 94%, and 86%.