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KNN 연구 요약서

Title Era-based comparison of survival and major morbidities in infants with birth weight less than 500 g in Korea: a nationwide cohort study, 2013–2024
Author Soo Hyun Kim, Euiseok Jung
작성자 정의석
Background Infants with birth weight (BW) < 500 g remain at the limit of viability and experience high rates of mortality and major neonatal morbidities. In a previous nationwide Korean Neonatal Network study of infants born during 2013–2017, survival to discharge was 28%, and major morbidities among survivors remained substantial. As perinatal and neonatal care may have evolved over time, an updated era-based comparison is needed. If differences in survival or morbidity are observed between eras, identifying factors associated with these differences may offer clinically meaningful insight.
Aim / Hypothesis The primary aim of this study is to compare survival to discharge between two eras, 2013–2018 and 2019–2024, among Korean infants with BW < 500 g. The secondary aims are to compare major neonatal morbidities and survival without major morbidity between the two eras and to identify perinatal and neonatal factors associated with any observed era-related differences in survival and morbidity.
Inclusion Criteria Live-born infants with BW < 500 g Gestational age ≥ 22 weeks Born between January 2013 and December 2024 Registered in the Korean Neonatal Network
Exclusion Criteria Infants with chromosomal defects or major congenital anomalies, Missing or unknown discharge outcome
Study Design Statistical methods This study will be a nationwide retrospective cohort study using prospectively collected KNN registry data. Eligible infants will be divided into two groups according to birth era: Era 1(2013–2018), Era 2(2019–2024). Baseline characteristics will be compared using the chi-square or Fisher’s exact test for categorical variables and the Student’s t-test or Mann–Whitney U test for continuous variables. Survival to discharge will be compared between the two eras using unadjusted and adjusted analyses. Multivariable logistic regression will be used to evaluate the independent association between birth era and survival after adjustment for major perinatal factors. Results will be presented as adjusted odds ratios with 95% confidence intervals. Major morbidities will be analyzed similarly. To reduce survivor bias, composite outcomes including death or major morbidity will also be examined. If significant era-related differences are observed, sequential multivariable models will be used to assess whether baseline characteristics and care-related factors partly explain these differences. Prespecified subgroup and sensitivity analyses will also be performed. A two-sided P value < 0.05 will be considered statistically significant.
Primary Outcomes Survival to discharge
Secondary Outcomes and Definitions Survival without major morbidity, Moderate-to-severe bronchopulmonary dysplasia, Severe intraventricular hemorrhage (grade III–IV), Periventricular leukomalacia, Necrotizing enterocolitis stage ≥ 2, Sepsis, Retinopathy of prematurity requiring treatment, Length of hospital stay, Cause and timing of death
Protocols KNN data from 2013 to 2024 will be analyzed for infants with BW < 500 g. Survival and major morbidities will be compared between the two eras. If significant differences are identified, additional adjusted analyses will be performed to determine whether those differences are associated with changes in case mix or potentially modifiable perinatal-neonatal care factors. A parallel table summarizing Korean outcomes and selected national or large international cohort data will also be prepared.
Funding None

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