Predictability of the neurodevelopmental assessment based on the Kyoto Scale of Psychological Development 2001 at 18–24 months of corrected age and 3 years of age in identifying cognitive impairment at 6 years of age in very preterm infants: A retrospective study at a Japanese tertiary center

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.