Objective: To determine whether a Bayley-III motor composite score of 85 may overestimate moderate-severe motor impairment by analyzing Bayley-III motor components and developing cut-point scores for each.
Study design: Retrospective study of 1183 children born <27 weeks gestation at NICHD Neonatal Research Network centers and evaluated at 18-22 months corrected age. Gross Motor Function Classification System determined gross motor impairment. Statistical analyses included linear and logistic regression and sensitivity/specificity.
Results: Bayley-III motor composite scores were strong indicators of gross/fine motor impairment. A motor composite cut-point of 73 markedly improved the specificity for identifying gross and/or fine motor impairment (94% compared with a specificity of 76% for the proposed new cut-point of 85). A Fine Motor Scaled Score <3 differentiated mild from moderate-severe fine motor impairment.
Conclusions: This study indicates that a Bayley-III motor composite score of 85 may overestimate impairment. Further studies are needed employing term controls and longer follow-up.