Recent neurodevelopmental outcomes of extremely and very preterm infants: A multicenter retrospective cohort study

초록

Background: Advances in neonatal intensive care have improved survival of extremely and very preterm infants, yet neurodevelopmental outcomes remain a major concern. Contemporary data on developmental trajectories and risk factors are essential for optimizing follow-up strategies. Methods: We conducted a retrospective cohort study of 193 preterm infants born at <32 weeks' gestation at two tertiary NICUs in Korea (2013-2024). Neurodevelopmental outcomes were assessed using the Korean Developmental Screening Test (K-DST) and Bayley Scales of Infant and Toddler Development, Third Edition (BayleyIII) at 18-24 months corrected age. The primary objective was to identify perinatal and neonatal risk factors associated with developmental delay (Bayley-III composite score < 70). Secondary objectives included evaluating the diagnostic accuracy of K-DST against Bayley-III, with temporal trends analyzed as an exploratory subanalysis. Risk factors were identified using Firth's penalized likelihood method, with overall and EP/VPstratified analyses. Results: Of 432 infants meeting the inclusion criterion of <32 weeks' gestation, 62 died before discharge, leaving 370 survivors. Of these, 193 (52.2%) completed neurodevelopmental follow-up at 18-24 months corrected age, including 175 (47.3%) with K-DST and 108 (29.2%) with Bayley-III assessments. K-DST screening (n = 175) identified 62.3% as below normal range, with language most frequently affected (38.9%). Bayley-III (n = 108) mean composite scores were 90.7 +/- 16.8 (cognitive), 89.3 +/- 19.4 (language), and 91.8 +/- 17.0 (motor), with delay prevalence of 12.0%, 13.9%, and 12.0%, respectively. EP infants scored significantly lower than VP infants in cognitive (84.3 vs. 93.5, p = 0.009) and motor (85.6 vs. 94.5, p = 0.020) domains. K-DST showed moderate sensitivity (58-85%) and specificity (75-85%) against Bayley-III thresholds, with high negative predictive value (>80%) supporting its utility as a screening instrument. On multivariate analysis adjusting for gestational age, sepsis (adjusted OR 4.75-6.16) and ROP requiring surgery (adjusted OR 1.85-59.71) were independently associated with developmental delay, although wide confidence intervals reflect model instability with limited events. In an exploratory subanalysis, the 2018-2024 birth cohort showed lower delay prevalence than the 2013-2017 cohort, but substantial case-mix differences (the earlier cohort had more EP infants and higher sepsis rates) preclude attribution to genuine improvements in care. Conclusion: ROP requiring surgery and sepsis were the most robust independent risk factors for developmental delay in extremely and very preterm infants. K-DST demonstrated acceptable diagnostic accuracy as a screening tool against Bayley-III. Apparent temporal improvements in outcomes are likely confounded by case-mix differences between birth era cohorts and should be considered hypothesis-generating. Comprehensive developmental surveillance using complementary instruments is essential for this population.

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