Concurrent validity and agreement of Bayley‐4, <scp>AIMS</scp> , and <scp>HINE</scp> assessments in 1‐year‐old children

AIM: To examine concurrent validity between the Bayley Scales of Infant and Toddler Development, Fourth Edition (Bayley-4) gross motor subtest and the Alberta Infant Motor Scale (AIMS), and evaluate agreement among the Bayley-4 (full test and gross motor subtest), AIMS, and Hammersmith Infant Neurological Examination (HINE) in identifying atypical development at 12 months of age. METHOD: This cross-sectional observational study included Bayley-4, AIMS, and HINE scores from 123 children (56 females, 67 males) with varied risk profiles at approximately 12 months of age. Concurrent validity was assessed using Spearman's rank correlation of raw scores. Agreement was evaluated using Cohen's kappa (k) and evidence-based thresholds of typicality for each assessment. Additional assessment comparisons, including AIMS and HINE, were conducted for benchmarking. RESULTS: The Bayley-4 gross motor subtest was strongly correlated (r = 0.90, p < 0.01) with the AIMS. Both the Bayley-4 full test and gross motor subtest demonstrated substantial agreement with the AIMS 5th centile (k = 0.72-0.73) and fair agreement (k = 0.28-0.32) with the HINE. By comparison, the AIMS and HINE were moderately correlated (r = 0.48), with fair agreement (k = 0.34). INTERPRETATION: This study provides the first evidence of concurrent validity and agreement for the Bayley-4, supporting its use as a reliable developmental assessment in clinical and home settings. The Bayley-4 aligned more closely with the motor-focused AIMS than with the neurologically focused HINE.