A psychometric study of the Bayley Scales of Infant and Toddler Development – 3rd Edition for term and preterm Taiwanese infants

The Bayley Scales of Infant and Toddler Development – 3rd Edition (Bayley-III) was updated to enhance its usefulness for contemporary child developmental assessment. However, recent data in Western countries have implicated the overestimation of child development by the new instrument. This study aimed to investigate the psychometric features of the Bayley-III for term and preterm infants in Taiwan. Forty-seven term infants and 167 preterm infants were prospectively examined with the Bayley Scales of Infant Development – 2nd Edition (BSID-II) and the Bayley-III at 6, 12, 18, and 24 months of age (corrected for prematurity). The psychometric properties examined included reliability, construct validity, and known-group validity. The intra- and inter-rater reliabilities of the Bayley-III were good to excellent. The correlations between the BSID-II and Bayley-III raw scores were good to excellent for the cognitive and motor items and low to excellent for the language items. Term infants achieved higher composite scores than preterm infants on all of the Bayley-III scales (p < 0.05). However, their rates of developmental delay were lower than the previously established prevalence estimates. The Bayley-III cut-off composite score was adjusted 10–20, 1–13, and 12–24 points higher than 70 for optimal prediction of cognitive, language, and motor delay, respectively, as defined by the BSID-II index score < 70. The Bayley-III is a reliable instrument that extends its previous edition, especially in early language assessment. However, the upward adjustment of its cut-off score is recommended for the accurate identification of developmental delay in term and preterm Taiwanese infants.