Background: The impact of weight or weight changes on kidney function remains a matter of debate. This study aimed to investigate the association between weight fluctuation and the incidence of end-stage renal disease (ESRD) using data from the Korean National Health Insurance Corporation health checkups (2009–2015). Methods: The study included 2,310,667 participants (1,546,749 men and 763,918 women), aged ≥40 years. Weight fluctuation was assessed using the average real variability (ARV) of weight and categorized into quartiles (Q1–Q4). Hazard ratios (HRs) and 95% confidence intervals for ESRD incidence were calculated using multivariable Cox proportional hazards models. Results: After adjustment for comorbidities, increased body mass index was associated with a decreased HR for ESRD. The highest quartile of weight variability (ARV Q4) demonstrated a higher probability and HR for ESRD compared to the lower variability quartiles (Q1–Q3). Among men, individuals with sustained weight, and those with weight gain, the ARV Q4 group showed significantly increased HRs for ESRD (HR of 1.372, 1.222, and 1.49, respectively). Furthermore, irrespective of changes in creatinine levels, all ARV Q4 groups exhibited increased HRs for ESRD (HR of 1.342, 1.472, and 1.299, respectively). Conclusions High weight fluctuation (ARV Q4) was associated with an increased incidence of ESRD in the general Korean population, with notable significance in men and in groups with sustained or increased weight. Clinically, individuals in the ARV Q4 category should be considered at risk for ESRD, and early interventions should be pursued for this population.

Purpose: This study aimed to investigate the effects of postnatal systemic corticosteroids on neurodevelopment in very low birth weight (VLBW) preterm infants. Methods: This was a population-based study of the Korean Neonatal Network of VLBW infant born at 23+0 and 31+6 weeks of gestation between 2013 and 2020. VLBW preterm infants assessed using the Bayley Scales of Infant and Toddler Development, third edition (BSID-III) at 18–24 months of corrected age and 3 years of age were enrolled. The primary outcomes were BSID-III scores and neurodevelopmental delays, with scores of <85. Socioeconomic status and clinical variables were adjusted for using multivariate regression analyses. Results: In total, 517 infants were enrolled in this study. Among the 216 (41.8%) infants who received postnatal systemic corticosteroids, the rate of cognitive delay was significantly higher at 18–24 months of corrected age than at 3 years of age. The rates of language and motor delays were significantly higher both at 18–24 months of corrected age and at 3 years of age. When multivariate logistic regression was performed, postnatal systemic corticosteroid use was significantly associated with cognitive delay at 18–24 months of corrected age, but not at 3 years of age. There was no significant association between postnatal systemic corticosteroid use and language or motor delay at 18-24 months of corrected age or at 3 years of age after multivariate logistic regression. Conclusion Postnatal systemic corticosteroid use in VLBW preterm infants increased the risk of cognitive delay at 18–24 months of corrected age, but not at 3 years.

Objective: Apnea in newborns is defined as a respiratory pause of 20 seconds or longer, or apnea accompanied by bradycardia or cyanosis. To date, research on neonatal apnea has focused on premature infants born within 34 weeks of gestation. The aim of this study is to present clinical significance of apnea in full-term infants compared with late premature infants born over 34 weeks of gestation. Methods: In a retrospective study, we reviewed medical records of neonates born over 34 weeks of gestation hospitalized for apnea and their mothers from November 2020 to May 2024. A total of 124 neonates were collected and divided into full-term infants (n=54) and late preterm infants (n=70) groups. Results: The mean gestational age of full-term and late preterm infants was 38 +5 weeks and 35 +2weeks, and the mean birth weight was 3.16 kg and 2.14 kg. Apnea was associated with diseases in 44.4% of full-term infants and 38.6% of late preterm infants. The rates of multiple births, small for gestational age, and cesarean section deliveries were significantly higher in late preterm infants.Apnea occurred significantly earlier and recovered faster in full-term infants. Neurologic disease was significantly more occurred in full-term infants (P=0.021). Especially, cerebral infarction and seizure were diagnosed only in full-term infants. Conclusion Apnea occurred earlier in full-term infants and severe neurologic diseases were significantly more found in full-term infants compared with late preterm infants. A close examination is needed in full-term infants with apnea.

Objective: Apnea in newborns is defined as a respiratory pause of 20 seconds or longer, or apnea accompanied by bradycardia or cyanosis. To date, research on neonatal apnea has focused on premature infants born within 34 weeks of gestation. The aim of this study is to present clinical significance of apnea in full-term infants compared with late premature infants born over 34 weeks of gestation. Methods: In a retrospective study, we reviewed medical records of neonates born over 34 weeks of gestation hospitalized for apnea and their mothers from November 2020 to May 2024. A total of 124 neonates were collected and divided into full-term infants (n=54) and late preterm infants (n=70) groups. Results: The mean gestational age of full-term and late preterm infants was 38 +5 weeks and 35 +2weeks, and the mean birth weight was 3.16 kg and 2.14 kg. Apnea was associated with diseases in 44.4% of full-term infants and 38.6% of late preterm infants. The rates of multiple births, small for gestational age, and cesarean section deliveries were significantly higher in late preterm infants.Apnea occurred significantly earlier and recovered faster in full-term infants. Neurologic disease was significantly more occurred in full-term infants (P=0.021). Especially, cerebral infarction and seizure were diagnosed only in full-term infants. Conclusion Apnea occurred earlier in full-term infants and severe neurologic diseases were significantly more found in full-term infants compared with late preterm infants. A close examination is needed in full-term infants with apnea.

Background/Aims: Krebs von den Lungen-6 (KL-6) is associated with prognosis in patients with COVID-19. However, there is limited data on the correlation between the prognosis of COVID-19 and varying KL-6 levels at different time points. We investigated the optimal cutoff values of the initial and peak serum KL-6 levels to predict mortality and evaluated their correlation with mortality. Methods: This retrospective cohort study collected data on serially collected serum KL-6 levels in patients hospitalized with COVID-19 between October 2020 and January 2022 at a single tertiary hospital in South Korea. The area under the receiver operating characteristic curve and Youden index were used to determine the cutoff points for the initial and peak KL-6 levels that best predicted 30-day mortality. The association between the initial and peak KL-6 values was assessed by univariate and multivariate logistic regression models. Results: A total of 349 patients were included in this study. The mean initial and peak KL-6 levels were significantly higher in the non-survivor group than in the survivor group. The initial and peak KL-6 values that best predicted 30-day mortality were 491.85 U/mL and 660.05 U/mL, respectively. An initial KL-6 level greater than 491.85 U/mL and a peak KL-6 level greater than 660.05 U/mL were significantly associated with 30-day mortality. Conclusions The initial and peak levels of KL-6 were significantly associated with 30-day mortality in hospitalized patients with COVID-19. These findings suggest that serially monitoring blood KL-6 levels could be a valuable prognostic indicator for COVID-19.

Purpose: This study aimed to investigate the effects of postnatal systemic corticosteroids on neurodevelopment in very low birth weight (VLBW) preterm infants. Methods: This was a population-based study of the Korean Neonatal Network of VLBW infant born at 23+0 and 31+6 weeks of gestation between 2013 and 2020. VLBW preterm infants assessed using the Bayley Scales of Infant and Toddler Development, third edition (BSID-III) at 18–24 months of corrected age and 3 years of age were enrolled. The primary outcomes were BSID-III scores and neurodevelopmental delays, with scores of <85. Socioeconomic status and clinical variables were adjusted for using multivariate regression analyses. Results: In total, 517 infants were enrolled in this study. Among the 216 (41.8%) infants who received postnatal systemic corticosteroids, the rate of cognitive delay was significantly higher at 18–24 months of corrected age than at 3 years of age. The rates of language and motor delays were significantly higher both at 18–24 months of corrected age and at 3 years of age. When multivariate logistic regression was performed, postnatal systemic corticosteroid use was significantly associated with cognitive delay at 18–24 months of corrected age, but not at 3 years of age. There was no significant association between postnatal systemic corticosteroid use and language or motor delay at 18-24 months of corrected age or at 3 years of age after multivariate logistic regression. Conclusion Postnatal systemic corticosteroid use in VLBW preterm infants increased the risk of cognitive delay at 18–24 months of corrected age, but not at 3 years.

Background/Aims: Krebs von den Lungen-6 (KL-6) is associated with prognosis in patients with COVID-19. However, there is limited data on the correlation between the prognosis of COVID-19 and varying KL-6 levels at different time points. We investigated the optimal cutoff values of the initial and peak serum KL-6 levels to predict mortality and evaluated their correlation with mortality. Methods: This retrospective cohort study collected data on serially collected serum KL-6 levels in patients hospitalized with COVID-19 between October 2020 and January 2022 at a single tertiary hospital in South Korea. The area under the receiver operating characteristic curve and Youden index were used to determine the cutoff points for the initial and peak KL-6 levels that best predicted 30-day mortality. The association between the initial and peak KL-6 values was assessed by univariate and multivariate logistic regression models. Results: A total of 349 patients were included in this study. The mean initial and peak KL-6 levels were significantly higher in the non-survivor group than in the survivor group. The initial and peak KL-6 values that best predicted 30-day mortality were 491.85 U/mL and 660.05 U/mL, respectively. An initial KL-6 level greater than 491.85 U/mL and a peak KL-6 level greater than 660.05 U/mL were significantly associated with 30-day mortality. Conclusions The initial and peak levels of KL-6 were significantly associated with 30-day mortality in hospitalized patients with COVID-19. These findings suggest that serially monitoring blood KL-6 levels could be a valuable prognostic indicator for COVID-19.

Purpose: This study aimed to investigate the effects of postnatal systemic corticosteroids on neurodevelopment in very low birth weight (VLBW) preterm infants. Methods: This was a population-based study of the Korean Neonatal Network of VLBW infant born at 23+0 and 31+6 weeks of gestation between 2013 and 2020. VLBW preterm infants assessed using the Bayley Scales of Infant and Toddler Development, third edition (BSID-III) at 18–24 months of corrected age and 3 years of age were enrolled. The primary outcomes were BSID-III scores and neurodevelopmental delays, with scores of <85. Socioeconomic status and clinical variables were adjusted for using multivariate regression analyses. Results: In total, 517 infants were enrolled in this study. Among the 216 (41.8%) infants who received postnatal systemic corticosteroids, the rate of cognitive delay was significantly higher at 18–24 months of corrected age than at 3 years of age. The rates of language and motor delays were significantly higher both at 18–24 months of corrected age and at 3 years of age. When multivariate logistic regression was performed, postnatal systemic corticosteroid use was significantly associated with cognitive delay at 18–24 months of corrected age, but not at 3 years of age. There was no significant association between postnatal systemic corticosteroid use and language or motor delay at 18-24 months of corrected age or at 3 years of age after multivariate logistic regression. Conclusion Postnatal systemic corticosteroid use in VLBW preterm infants increased the risk of cognitive delay at 18–24 months of corrected age, but not at 3 years.

Objective: Apnea in newborns is defined as a respiratory pause of 20 seconds or longer, or apnea accompanied by bradycardia or cyanosis. To date, research on neonatal apnea has focused on premature infants born within 34 weeks of gestation. The aim of this study is to present clinical significance of apnea in full-term infants compared with late premature infants born over 34 weeks of gestation. Methods: In a retrospective study, we reviewed medical records of neonates born over 34 weeks of gestation hospitalized for apnea and their mothers from November 2020 to May 2024. A total of 124 neonates were collected and divided into full-term infants (n=54) and late preterm infants (n=70) groups. Results: The mean gestational age of full-term and late preterm infants was 38 +5 weeks and 35 +2weeks, and the mean birth weight was 3.16 kg and 2.14 kg. Apnea was associated with diseases in 44.4% of full-term infants and 38.6% of late preterm infants. The rates of multiple births, small for gestational age, and cesarean section deliveries were significantly higher in late preterm infants.Apnea occurred significantly earlier and recovered faster in full-term infants. Neurologic disease was significantly more occurred in full-term infants (P=0.021). Especially, cerebral infarction and seizure were diagnosed only in full-term infants. Conclusion Apnea occurred earlier in full-term infants and severe neurologic diseases were significantly more found in full-term infants compared with late preterm infants. A close examination is needed in full-term infants with apnea.

Background/Aims: Krebs von den Lungen-6 (KL-6) is associated with prognosis in patients with COVID-19. However, there is limited data on the correlation between the prognosis of COVID-19 and varying KL-6 levels at different time points. We investigated the optimal cutoff values of the initial and peak serum KL-6 levels to predict mortality and evaluated their correlation with mortality. Methods: This retrospective cohort study collected data on serially collected serum KL-6 levels in patients hospitalized with COVID-19 between October 2020 and January 2022 at a single tertiary hospital in South Korea. The area under the receiver operating characteristic curve and Youden index were used to determine the cutoff points for the initial and peak KL-6 levels that best predicted 30-day mortality. The association between the initial and peak KL-6 values was assessed by univariate and multivariate logistic regression models. Results: A total of 349 patients were included in this study. The mean initial and peak KL-6 levels were significantly higher in the non-survivor group than in the survivor group. The initial and peak KL-6 values that best predicted 30-day mortality were 491.85 U/mL and 660.05 U/mL, respectively. An initial KL-6 level greater than 491.85 U/mL and a peak KL-6 level greater than 660.05 U/mL were significantly associated with 30-day mortality. Conclusions The initial and peak levels of KL-6 were significantly associated with 30-day mortality in hospitalized patients with COVID-19. These findings suggest that serially monitoring blood KL-6 levels could be a valuable prognostic indicator for COVID-19.