Predictive value of Bayley-III Motor Index for later motor difficulties in children born extremely preterm

Aim: To investigate the predictive ability of the Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III) Motor Index, in children born extremely preterm (<27 gestational weeks) without cerebral palsy. Methods: Children from the EXPRESS study (all extremely preterm births in Sweden, 2004–2007) without neurosensory impairments assessed with Bayley-III at 2.5 years corrected age and Movement Assessment Battery for Children, Second Edition (MABC-2), at 6.5 years comprised the eligible study population (n = 282). Motor difficulty was defined as MABC-2 ≤5th percentile. Results: Motor difficulties were found in 57 of 282 children (20.2%) at 6.5 years. The Bayley-III explained 18.0% of the variance in the MABC-2 (p < 0.001). The area under the receiver operating curve was 0.71 (95% confidence interval 0.64−0.79, p < 0.001). At a Bayley-III cut-off value of 85, sensitivity, specificity and positive and negative predictive values for motor difficulties were 26.3% (15.5–39.7), 92.9% (88.1–95.9), 48.4% (33.0–64.0) and 83.3% (80.9–85.4). Likelihood ratios were inconclusive. Conclusion: The Bayley-III at 2.5 years corrected age was a modest predictor of motor outcome in children born extremely preterm at 6.5 years, and underestimated the rate of motor difficulties. Children require follow-up beyond preschool age