Do Bayley-III Composite Scores at 18-22 Months Corrected Age Predict Full-Scale IQ at 6-7 Years in Children Born Extremely Preterm?

Abstract

Objective: To determine the ability of the Bayley-III cognitive and language composite scores at 18-22 months corrected age to predict WISC-IV Full Scale IQ (FSIQ) at 6-7 years in infants born extremely preterm.

Study design: Children in this study were part of the Neuroimaging and Neurodevelopmental Outcome cohort, a secondary study to the SUPPORT trial and born 24^0/7-27^6/7 weeks gestational age. Bayley-III cognitive and language scores and WISC-IV FSIQ were compared with pairwise Pearson correlation coefficients and adjusted for medical and socioeconomic variables using linear mixed effect regression models.

Results: Bayley-III cognitive (r = 0.33) and language scores (r = 0.44) were mildly correlated with WISC-IV FSIQ score. Of the children with Bayley-III cognitive scores of <70, 67% also had FSIQ of <70. There was less consistency for children with Bayley-III scores in the 85-100 range; 43% had an FSIQ of <85 and 10% an FSIQ of <70. Among those with Bayley-III language scores >100, approximately 1 in 5 had an FSIQ of <85. A cut point of 92 for the cognitive composite score resulted in sensitivity (0.60), specificity (0.64). A cut point of 88 for the language composite score produced sensitivity (0.61), specificity (0.70).

Conclusions: Findings indicate the Bayley-III cognitive and language scores correlate with later IQ, but may fail to predict delay or misclassify children who are not delayed at school age. The Bayley-III can be a useful tool to help identify children born extremely preterm who have below average cognitive scores and may be at the greatest risk for ongoing cognitive difficulties.

Trial registration: Extended Follow-up at School Age for the SUPPORT Neuroimaging and Neurodevelopmental Outcomes (NEURO) Cohort: NCT00233324.

Keywords: Neurodevelopment; prematurity; school-age outcomes.