Correlation between the Bayley-III at 3 years and the Wechsler Intelligence Scale for Children, Fourth Edition, at 6 years

Background: Although several studies have investigated the association between Bayley-III results in infancy and future intellectual development, conclusions remain unclear. We used the Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III) at 3 years of age and the Wechsler Intelligence Scale for Children, Fourth Edition (WISC-IV) at 6 years of age to assess the neurodevelopment of very low birthweight infants. Methods: We investigated the correlation between Bayley-III's cognitive, language, and motor scores and the WISC-IV's Full-Scale Intelligence Quotient (FSIQ). We also determined the optimal cut-off value of Bayley-III to enter the normal development zone (FSIQ ≥ 85). Results: We found a strong correlation between the Bayley-III and the FSIQ. Optimal cut-off scores of the Bayley-III to enter the normal range on the WISC-IV were 95 for the cognitive scale, 89 for the language scale, and 91 for the motor development scale. Conclusions: Although Bayley-III scores strongly correlated with the WISC-IV FSIQ, the lower normal limit of 85 on the Bayley-III suggests a potential overestimation of development in children who were VLBW infants.