Predictive validity of the Bayley, Third Edition at 2 years for intelligence quotient at 4 years in preterm infants.

Objective: To determine the predictive validity of the Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III) at age 2 years for cognitive abilities in preschool children born at ≤ 30 weeks' gestation.

Methods: This prospective regional study included all 187 liveborn infants ≤ 30 weeks' gestation born between July 2005 and June 2006. Of the 172 children who survived to 4 years, 156 (91%) were evaluated at 2 and 4 years. A socioeconomically matched term control group also was recruited to provide normative data. The predictive validity of the Bayley-III cognitive and language scales for the Weschler Preschool and Primary Scale of Intelligence-III (WPPSI-III) was examined through correlation coefficients and sensitivity and specificity of the Bayley-III to predict normal and abnormal cognitive outcomes.

Results: Correlations of the WPPSI-III intelligence quotient (IQ) score with the Bayley-III cognitive and language scores were .81 and .78, respectively. The preterm children were classified as normal (Bayley Scales of Infant Development-Third Edition [BSID-III] cognitive score or WPPSI-III IQ score not lower than 1 SD below the control group mean), mild to moderately delayed (scores between 1 and 2 SD deviations below the control group mean), or severely delayed (scores greater than 2 SD below the control group mean). At 2 and 4 years, 126 (81%) preterm children retained the same developmental classification.

Conclusions: In contrast with previous editions of the BSID, the Bayley-III has strong predictive validity for WPPSI-III IQ at age 4 years in preterm children. This has important implications for more timely evaluation of perinatal interventions, establishment of guidelines for neonatal care, and counseling parents.