RESUMO
BACKGROUND: It is unknown how accurately the current Japanese classification system for neurodevelopmental delay based on the assessment with the Kyoto Scale of Psychological Development (KSPD) at toddlerhood and pre-school periods predicts cognitive impairment at school age. METHODS: This single-center retrospective cohort study enrolled infants born at 22-29 weeks of gestational age. At 18-24 months of corrected age and 3 years of age, the patients were categorized according to the current Japanese criteria for neurodevelopmental delay based on their overall developmental quotient calculated using the KSPD-2001. Cognitive impairment at 6 years of age was classified according to the calculated or estimated full-scale intelligence quotient. The predictability of the current Japanese classification of neurodevelopmental delay for cognitive impairment at 6 years of age was investigated. RESULTS: Of 566 eligible patients, 364 (64 %) completed the protocol. The current classification for the neurodevelopmental delay showed significant agreement with the severity of cognitive impairment at 6 years of age. The sensitivity and specificity of the KSPD-2001-based assessment for any cognitive impairment at 6 years of age were 0.64 and 0.74 at 18-24 months of corrected age and 0.83 and 0.70 at 3 years of age. The corresponding sensitivity and specificity for moderate/severe cognitive impairment were 0.51 and 0.96 at 18-24 months of corrected age and 0.68 and 0.95 at 3 years of age. CONCLUSION: The KSPD-2001 is a useful tool to predict the severity of cognitive impairment at school age.