Cohort profile: National Investigation of Birth Cohort in Korea study 2008 (NICKs-2008)

Diverse weaning foods and diet patterns at multiple time points during infancy period and their association with neurodevelopmental outcomes in 6-year-old children

BACKGROUND/OBJECTIVES

Understanding the impact of early-life nutritional choices on neurodevelopment in children is a growing area of research. To investigate the association between dietary patterns at multiple timelines and neurodevelopmental outcomes in 6-year-old children.

SUBJECTS/METHODS

This administrative observational study utilized a merged data from the national health insurance database and the health screening program for children. Information on the diet patterns from infancy to 3 years of age was obtained from parent-administered questionnaires. Dietary pattern clusters of the participants were identified using Polytomous Latent Class Analysis. The outcome was neurodevelopment using the Korean Developmental Screening Test (K-DST) at the age of 6 years.

RESULTS

The study identified four distinct clusters among with the 133,243 eligible children (49.6% male, birth weight 3.22 kg, head circumference 42.7 cm at 4 months). The control cluster (53.4%) exhibited a diet including breast milk feeding and a variety of dietary patterns at the age of 1 year. In contrast, cluster 1 (36.0%) showed a skewed dietary pattern at the same age. Cluster 2 (6.6%) displayed diverse dietary patterns at one year but primarily consumed formula at four months, while cluster 3 (4.0%) had reduced dietary diversity and formula feeding. Compared with the control cluster, the adjusted odds ratio for unfavorable development was 1.209 (95% CI, 1.156-1.266) in cluster 1, 1.418 (95% CI, 1.312-1.532) in cluster 2, and 1.741 (95% CI, 1.593-1.903) in cluster 3. These findings remained consistent across individual domains of the K-DST.

CONCLUSIONS

Dietary patterns during infancy and early childhood may be associated with neurodevelopment at the age of 6 years.

Long-Term Mental Health Outcomes of Bronchopulmonary Dysplasia in Neonates: An 18-Year National Cohort Study

OBJECTIVE

To evaluate the association between neonatal bronchopulmonary dysplasia and the subsequent development of mental health conditions in children and adolescents.

STUDY DESIGN

This was a retrospective cohort study, utilizing data from individuals born in South Korea between 2002 and 2005 and followed up until 2021, using the National Health Insurance Database. The cohort included 1,893,314 participants born during that period, with 927 diagnosed with bronchopulmonary dysplasia during the neonatal period (the exposed cohort). They were matched 1:10 with 9,270 unexposed individuals (the unexposed cohort) based on key demographic factors.

RESULTS

The median age at the first mental health disorder diagnosis was 9 years (interquartile range, 5-15 years), with 5,698 individuals (55.9%) being male. During an average follow-up of 15.2 years, the incidence rate was 481/10,000 person-years in the exposed and 138/10,000 person-years in the unexposed cohort. By the age of 18 years, the cumulative incidence in the exposed cohort was 54% (95% confidence interval [CI]; 50%-57%), with an adjusted hazard ratio of 3.18 (95% CI; 2.81-3.60) compared with the unexposed cohort, and adjusted hazard ratios for early- and late-onset mental health disorders of 4.48 (95% CI; 3.84-5.22) and 1.89 (95% CI; 1.61-2.22), respectively. Sensitivity analyses confirmed these findings, and a subgroup analysis revealed a higher risk among individuals with bronchopulmonary dysplasia who required prolonged respiratory support or oxygen.

CONCLUSIONS

Half of children with bronchopulmonary dysplasia in our cohort developed mental health disorders by the age of 18 years, emphasizing the need for interventions and support for such individuals.

Neurodevelopmental outcomes among children with congenital gastrointestinal anomalies using Korean National Health Insurance claims data

This study investigated neurodevelopment and risk factors in children surgically treated for congenital gastrointestinal anomalies (CGIA), excluding those with known high-risk factors such as low birth weight or chromosomal anomalies. Data of children born between 2008 and 2015 who underwent surgical treatment for CGIA were retrieved from the Korean National Health Insurance Database. CGIA included esophageal atresia, duodenal atresia, jejunoileal atresia, anorectal malformations, and congenital megacolon. Neurodevelopmental impairment (NDI) was defined as Korean Ages and Stages Questionnaire scores below the determined cut-off or Korean Developmental Screening Test scores < 2 standard deviations at 3 years of age. Children with CGIA had a significantly higher risk of NDI than controls (6.2% vs. 2.7%, p < 0.001). Growth failure was correlated with NDI. Longer durations of oxygen support (adjusted odds ratio [aOR], 1.037; 95% confidence interval [CI], 1.013-1.063), mechanical ventilation (aOR, 1.053; 95% CI, 1.018-1.089), and number of surgeries (aOR, 1.137; 95% CI, 1.016-1.273) were significantly associated with NDI. These findings emphasize that cautious yet proactive neurodevelopmental monitoring is crucial in affected children, ensuring timely intervention and that excessive concern among families is unnecessary.

Long-term impact of weight loss in people with class II obesity on the overall burden of disease: Evidence from the National Health Screening Cohort in Korea

BACKGROUND

Obesity is known to increase overall disease burden but does obesity management actually help reduce disease burden?

OBJECTIVES

To investigate the effects of weight loss on disease burden in people with obesity using the National Health Insurance Service-Health Screening Cohort (NHIS-HEALS) in Korea.

SETTING

Pure longitudinal observational study using Nationwide cohort database.

METHODS

Out of 514,866 NHIS-HEALS cohort, participants with class II obesity in Asia-Pacific region (30 ≤ body mass index [BMI] < 35) who underwent health check-up provided by NHIS during 2003-2004 (index date) were included. All final participants continued to receive a total of 5 biennial health check-ups over the next 10 years without missing. A group-based trajectory model (GBTM) was used to categorize subjects based on 10-year BMI change patterns. The changes of co-morbidities, healthcare resource utilization, and medical cost were analyzed.

RESULTS

The final study subjects (9857) were categorized into 3 trajectory clusters based on the pattern of BMI (kg/m2) change: maintenance (57.35%) with an average change of -.02 ± .06, loss (38.65%) with -.04 ± .08, and substantial loss (4.0%) with -.10 ± .18. The annual increases in the number of co-morbidities per subject in each cluster were .18, .18, and .16 (all P < .001), respectively. The increase of healthcare resource utilization over time was lowest for the substantial loss compared to maintenance and loss. With each passing year, the average annual total healthcare cost increased by ₩21,200 ($16.48, P = .034) and ₩10,500 ($8.16, P = .498) in the maintenance and loss, respectively, but decreased by ₩62,500 ($48.59, P = .032) in the substantial loss.

CONCLUSIONS

Weight loss in people with obesity was associated with a reduced burden of disease, as evidenced by lower co-morbidity, healthcare resource utilization rate, and decreased medical costs. This study highlights the potential positive long-term impact on Korean society when actively managing weight in individuals with obesity.

Age-related effects of Mycoplasma pneumoniae infection and subsequent asthma exacerbation in children

BACKGROUND

Mycoplasma pneumoniae causes community-acquired pneumonia in children and increases asthma risk, but large studies are lacking.

OBJECTIVE

To assess the link between M. pneumoniae infection and to asthma exacerbation, in children with allergies, and age of infection impact.

METHODS

This retrospective cohort study analyzed medical records of South Korean children between January 2002 and December 2017. The study's exposure was hospitalization with an M. pneumoniae-related diagnosis, and the outcome was defined as asthma exacerbation, confirmed by hospitalization at least 6 months after M. pneumoniae infection, with alternative validation using asthma diagnosis and systemic steroid prescription records. Hazard ratios (HRs) for asthma exacerbation risk were estimated for the matched cohort using a Cox proportional hazards model stratified by allergic comorbidities. Time-dependent covariates and age-stratified exposure groups were used to calculate odds ratios.

RESULTS

The study included 84,074 children with M. pneumoniae infection and 336,296 unexposed children. Follow-up for 12.2 ± 2.3 years found the exposed group had a significant risk of asthma exacerbation (HR 2.86, 95% confidence interval [CI] 2.67-3.06) regardless of allergic comorbidities. The risk was highest (over threefold) in children infected between 24 and 71 months. Sensitivity analysis using an alternative definition of the outcome showed an HR of 1.38 (95% CI 1.35-1.42), further supporting the association between M. pneumoniae infection and asthma exacerbation.

CONCLUSION

M. pneumoniae infection was significantly associated with an increased risk of subsequent asthma exacerbation regardless of allergic comorbidities. Further research needed for understanding and confirmation.

Consumption of Sugar-Sweetened Beverages before 2 Years of Age and Attention-Deficit/Hyperactivity Disorder

INTRODUCTION

This study examined the association between sugar-sweetened beverage consumption before the first 24 months of life and attention-deficit/hyperactivity disorder (ADHD).

METHODS

A population administrative cohort study was conducted in Korea (2008-2019) using linked national insurance data and a health screening survey. The cohort included 25,305 children in the exposed group with high sugar-sweetened beverage drinks (≥200 mL) and 339,931 in the reference groups (<200 mL) at 24 months of age. The primary outcome was the development of ADHD based on the International Classification of Disease (ICD) codes. Cox proportional model was used to identify the association between sugar-sweetened beverage consumption during early childhood and the later development of ADHD while controlling for multiple risk factors.

RESULTS

Over a mean follow-up period of 9.2 years, the incidence rates of ADHD were 29.6 and 23.8 per 10,000 person-years in the exposed and reference groups, respectively. Compared with the reference group, children consuming high-sugar drinks were at an increased risk of ADHD (adjusted hazard ratio 1.17, 95% confidence interval [CI] 1.08-1.27). These associations remained significant even after applying alternative ADHD definitions or adjusting for confounding variables.

CONCLUSION

Children who consume sweetened beverages during early childhood are at increased risk of developing ADHD later in life.

The incidence and risk factors of retinopathy of prematurity in South Korea: A nationwide cohort study

Retinopathy of prematurity (ROP) is a major treatable cause of childhood blindness. Thus, epidemiological investigations are necessary for detecting and preventing ROP. Determining risk factors for ROP are also essential to improve screening methods. Therefore, we aimed to investigate the incidence and risk factors of ROP in Korea. The National Health Insurance Service (NHIS) covers almost all Koreans. Furthermore, the National Health Screening Program for Infants and Children (NHSPIC) is a government-run, health-screening program for children aged < 6 years. We used the NHIS-Infants and Children's Health Screening cohort database to evaluate the incidence of preterm infants and ROP. The database contains data on 84,005 participants, drawn from 5% of the NHSPIC survey on participants born annually during 2008 to 2012. Sociodemographic factors and systemic diseases were assessed as potential risk factors for ROP. We identified 2615 premature infants (3.11%); 846 of them had ROP (cumulative incidence: 32.4%). Although preterm births increased annually in 2008 to 2012, the ROP incidence in preterm infants did not increase by the birth year. Twenty patients (2.4%) with ROP underwent laser photocoagulation or surgery. Extremely low birth weight was a high risk factor (odds ratio [OR] = 49.86, P < .001). Moreover, chorioamnionitis (OR = 2.77, P = .028), respiratory distress syndrome (OR = 4.09, P < .001), apnea (OR = 1.59, P = .008), anemia (OR = 2.41, P < .001), and intraventricular hemorrhage (OR = 2.34, P < .001) were found to be risk factors for ROP. In conclusion, the incidence of premature babies increased between 2008 and 2012. However, the overall incidence of ROP among premature infants remained unchanged by birth year. Our findings revealed the roles of birth weight, respiratory conditions, anemia, and intraventricular hemorrhage in ROP.

Association between the COVID-19 pandemic and childhood development aged 30 to 36 months in South Korea, based on the National health screening program for infants and children database

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic has had a significant impact on the neurodevelopment of children. However, the precise effects of the virus and the social consequences of the pandemic on pediatric neurodevelopment are not yet fully understood. We aimed to compare the neurodevelopment of children between before and during the COVID-19 pandemic, as well as examine the impact of socioeconomic status (SES) and regional differences on the development.

METHODS

The study used the Korean Developmental Screening Test to compare the difference in the risk of neurodevelopmental delay between before and during the COVID-19 pandemic. Multivariable logistic regression analysis was conducted to identify the relationship between experiencing the COVID-19 pandemic and the risk of neurodevelopmental delay. Stratified analyses were performed to determine whether the developmental delays caused by the pandemic's impact varied depending on SES or regional inequality.

RESULTS

This study found an association between the experience of COVID-19 and a higher risk of neurodevelopmental delay in communication (adjusted OR [aOR]: 1.21, 95% confidence interval [CI]: 1.19, 1.22; P-value: < 0.0001) and social interaction (aOR: 1.15, 95% CI: 1.13, 1.17; P-value: < 0.0001) domains among children of 30-36 months' ages. Notably, the observed association in the Medicaid group of children indicates a higher risk of neurodevelopmental delay compared to those in the non-Medicaid group.

CONCLUSIONS

These findings highlight the need to be concerned about the neurodevelopment of children who experienced the COVID-19 pandemic. The study also calls for increased training and support for Medicaid children, parents, teachers, and healthcare practitioners. Additionally, policy programs focused on groups vulnerable to developmental delays are required.

Unraveling the link between atopic dermatitis and autoimmune diseases in children: Insights from a large-scale cohort study with 15-year follow-up and shared gene ontology analysis

BACKGROUND

Atopic dermatitis and autoimmune diseases are highly heritable conditions that may co-occur from an early age.

METHODS

The primary study is a national administrative cohort study involving 499,428 children born in 2002, tracked until 2017. Atopic dermatitis was defined as five or more principal diagnoses of atopic dermatitis and two or more topical steroid prescriptions. We estimated the risks for the occurrence of 41 autoimmune diseases, controlling for risk factors. In addition, we sourced a gene library from the National Library of Medicine to conduct a comprehensive gene ontology. We used Gene Weaver to identify gene set similarity and clustering, and used GeneMania to generate a network for shared genes.

RESULTS

Exposed and unexposed groups included 39,832 and 159,328 children, respectively. During a mean follow-up of 12 years, the exposed group had an increased risk of autoimmune disease (hazard ratio, 1.27 [95 % confidence interval, 1.23-1.32]) compared to the unexposed group. The hazard ratios of autoimmune illnesses consistently increased with two- and five years lag times and alternative atopic dermatitis definitions. Shared genes between atopic dermatitis and autoimmune diseases were associated with comorbidities such as asthma, bronchiolitis, and specific infections. Genetic interactions of these shared genes revealed clustering in Th1, Th2, Th17, and non-classifiable pathways.

CONCLUSIONS

Atopic dermatitis was significantly associated with an increased risk of subsequent autoimmune disease. we identified the genetically associated disease in atopic dermatitis patients comorbid with autoimmune disease and demonstrated a genetic network between atopic dermatitis and autoimmune diseases.

Trends in Incidence and Drug Prescriptions for Croup in Children Under 5 Years of Age: A 2002-2019 Population-Based Study

BACKGROUND

Tracking national croup trends can provide important insights for childhood health management. This study aimed to analyze the incidence and drug prescription trends in Korean children over a two-decade period.

METHODS

This population-based study encompassed 479,783 children aged < 5 years from 2002-2019, utilizing the National Health Insurance Service-National Sample Cohort. We identified participants with a primary croup diagnosis who were admitted to or visited the emergency room. Age-specific and age-adjusted incidence rates/10,000 person-years were calculated. We assessed using orthogonal polynomial contrasts and stratified by various factors (sex, age, residential area, economic status, comorbidities, and healthcare facility types). We observed changes in the use of five medications: inhaled steroids, systemic steroids, inhaled epinephrine, antibiotics, and short-acting bronchodilators. Generalized binomial logistic regression was used to analyze factors influencing prescription strategies.

RESULTS

In 2002, the croup-related visits were 16.1/10,000 person-years, increasing to 98.3 in 2019 (P for trend < 0.001). This trend persisted, regardless of age, sex, region, and economic status. Children with comorbid atopic dermatitis or asthma maintained consistent croup rates, while those without comorbidities increased. Treatment trends showed decreasing antibiotic (73-47%) and oxygen use (21.3-3.4%), with increasing nebulized epinephrine (9.3-41.5%) and multiple drug prescriptions (67.8-80.3%). Primary care centers exhibited a greater increase in prescription usage and hospitalization duration than did tertiary healthcare institutions.

CONCLUSION

Over the past two decades, croup incidence has risen, accompanied by increased epinephrine use and decreased antibiotic prescriptions. Longer hospitalization and higher medication use were mainly observed in primary care facilities.

Neurodevelopment in Term Infants with Normal Birthweight following Postnatal Systemic Steroid Exposure

INTRODUCTION

Studies investigating the potential impact of systemic steroid exposure during early infancy on neurological development in full-term infants with normal birth weight are lacking.

METHODS

This population-based administrative cohort study used data of national health insurance and a health-screening program for infants and children and included full-term infants who were born in Korea between 2008 and 2012 with normal birth weight and did not have any specific perinatal or neurodevelopmental diseases. The prescription of systemic steroids within the first 3 months of age was mainly considered. The neurological development of children was assessed using the Korean Development Screening Test (K-DST) at 6 years of age. To balance the baseline characteristics of the control and exposed groups, stabilized inverse probability of treatment weighting with trimming was performed in the main cohort. Ordinal logistic regression was used to assess the association between systemic steroid exposure and unfavorable results in the K-DST.

RESULTS

The control and exposure groups had 246,168 and 5,083 children, respectively. The K-DST suggested unfavorable results in 8.1% and 8.6% children in the control and exposure groups, respectively (weighted odds ratio, 95% confidence interval, 1.03, 0.93-1.14). When each domain of the K-DST was considered separately, the risk of unfavorable results in the exposed group was not significantly different from that in the control group.

CONCLUSIONS

No significant association was observed between exposure to systemic steroids during early infancy and neurodevelopmental impairment at 6 years of age.

Investigating the occurrence of autoimmune diseases among children and adolescents hospitalized for Mycoplasma pneumoniae infections

Background

Mycoplasma pneumoniae infection is common in the general population and may be followed by immune dysfunction, but links with subsequent autoimmune disease remain inconclusive.

Objective

To estimate the association of M. pneumoniae infection with the risk of subsequent autoimmune disease.

Methods

This retrospective cohort study examined the medical records of South Korean children from 01/01/2002 to 31/12/2017. The exposed cohort was identified as patients hospitalized for M. pneumoniae infection. Each exposed patient was matched with unexposed controls based on birth year and sex at a 1:10 ratio using incidence density sampling calculations. The outcome was subsequent diagnosis of autoimmune disease, and hazard ratios (HRs) were estimated with control for confounders. Further estimation was performed using hospital-based databases which were converted to a common data model (CDM) to allow comparisons of the different databases.

Results

The exposed cohort consisted of 49,937 children and the matched unexposed of 499,370 children. The median age at diagnosis of M. pneumoniae infection was 4 years (interquartile range, 2.5-6.5 years). During a mean follow-up time of 9.0 ± 3.8 years, the incidence rate of autoimmune diseases was 66.5 per 10,000 person-years (95% CI: 64.3-68.8) in the exposed cohort and 52.3 per 10,000 person-years (95% CI: 51.7-52.9) in the unexposed cohort, corresponding to an absolute rate of difference of 14.3 per 10,000 person-years (95% CI: 11.9-16.6). Children in the exposed cohort had an increased risk of autoimmune disease (HR: 1.26; 95% CI: 1.21-1.31), and this association was similar in the separate analysis of hospital databases (HR: 1.25; 95% CI 1.06-1.49).

Conclusion

M. pneumoniae infection requiring hospitalization may be associated with an increase in subsequent diagnoses of autoimmune diseases.

Assessment of Neurodevelopment and Growth in Congenital Hypothyroidism: Serial 6-Year Follow-up Study of 408 Patients

CONTEXT

The link between congenital hypothyroidism (CH) and neurodevelopment is suggested, yet studies applying quantifiable measures are lacking. Moreover, socioeconomic disparities and subtle variation in timing of approach make the relationship difficult to detect.

OBJECTIVE

To evaluate associations between CH and abnormalities in neurodevelopment and growth and determine the critical period for intervention.

METHODS

We utilized a nationwide database to conduct a longitudinal analysis of 919 707 children. Exposure to CH was identified using claims-based data. The primary outcome of interest was suspected neurodevelopmental disorder, as measured using the Korean Ages & Stages Questionnaires (K-ASQ) administered annually from 9 to 72 months of age. Secondary outcomes were height and BMI z-scores. After randomly matching cases and controls at a 1:10 ratio, we employed inverse probability of treatment weighting and generalized estimating equation models for our analyses. We conducted subgroup analysis based on the age of treatment initiation.

RESULTS

The prevalence of CH in our population was 0.05% (n = 408). Relative to the control group, the CH group had higher risk of suspected neurodevelopmental disorders (propensity score-weighted odds ratio: 4.52; 95% CI: 2.91, 7.02), and significantly increased risk in each of the 5 K-ASQ domains. No time interactions were noted at any rounds for the outcomes according to when the neurodevelopmental assessment was conducted (all P for interaction >.05). The CH group also had higher risk for low height-for-age z-score, but not for elevated BMI-for-age z-score. In subgroup analysis, delayed medication for CH correlated with worse neurodevelopmental outcomes.

CONCLUSION

The CH group had worse neurodevelopmental outcomes and reduced height-for-age z-score. Outcomes were worse when onset of treatment was increasingly delayed.

Relationship between short stature at 3 years old and height, weight, and body mass index changes for 6 years after birth: a retrospective, nationwide, population-based study of children born 2011-2014 in Korea

PURPOSE

Height at 3 years of age, when catch-up growth based on birth history is completed, is considered a major prognostic factor for predicting short stature, underweight, and growth faltering. However, too few large-scale studies have followed and analyzed height, weight, and body mass index (BMI) changes in children whose stature was short at 3 years of age. This study followed and compared the growth parameters (height, weight, and BMI) of children with short stature at 3 years of age and children with nonshort stature at 3 years of age for 6 years after birth using nationwide, population-based data.

METHODS

We retrospectively analyzed physical measurement data from the National Health Screening Program for Infants and Children for people born in 2011-2014 in Korea and followed to 2020. The data were provided by the National Health Insurance Service's customized data service. Growth parameters were compared using chi-square tests, Student t-tests, analyses of variance, and linear regressions.

RESULTS

Among 210,902 enrolled participants, 759 (0.4%) and 210,143 (99.6%) were in the short stature at 3 years group and the nonshort stature at 3 years group, respectively. In both sexes, height, weight, and BMI for 6 years after birth were significantly higher in the nonshort stature at 3 years group than in the short stature at 3 years group (P<0.0001). The BMI rebound was observed later than the standard period in the short stature at 3 years group.

CONCLUSION

Early intervention and close follow-up are necessary to prevent persistent short stature and growth faltering in children with short stature at 3 years of age.

Associations between Delayed Introduction of Complementary Foods and Childhood Health Consequences in Exclusively Breastfed Children

The timing of complementary food (CF) introduction is closely related to childhood health, and it may vary depending on the region, culture, feeding type, or health condition. Despite numerous studies on the benefits of breastfeeding and the optimal timing of CF introduction, there have been limited investigations regarding delayed CF introduction in exclusively breastfed children. We compared an exposed group (CF introduction ≥7 months) with a reference group (CF introduction at 4 -< 7 months) regarding hospital admission, disease burden, and growth until age 10. Data from a nationwide population-based cohort study involving children born between 2008 and 2012 in the South Korea were analyzed. The final cohort comprised 206,248 children (165,925 in the exposed group and 40,323 in the reference group). Inverse probability of treatment weighting with propensity score matching was used to balance baseline health characteristics in the comparison groups. We estimated the incident risk ratios (IRR) for outcomes using modified Poisson regression and weighted odds ratios (weighted ORs) and their 95% confidence intervals (CIs) using multinomial logistic regression. The exposed group was associated with low height-for-age z-score (HAZ) (IRR (95% CI) for -1.64 < HAZ ≤ -1.03: 1.11 (1.08 to 1.14); HAZ ≤ -1.64: 1.21 (1.14 to 1.27)) and frequent (≥6 events) hospitalizations (weighted OR 1.18 (1.09 to 1.29). The rates of hospital admission, death, and specific medical conditions did not differ between groups. However, delaying the introduction of CF until seven months in exclusively breastfed infants was associated with frequent hospitalization events and lower heights.

Association between First-Generation Antihistamine Use in Children and Cardiac Arrhythmia and Ischemic Heart Disease: A Case-Crossover Study

Cardiotoxicity from first-generation H1-antihistamines has been debated since the 1990s. However, large-scale studies on this topic in a general pediatric population are lacking. This study aimed to assess the association between first-generation H1-antihistamine use and cardiovascular events in a nationwide pediatric population. In this case-crossover study, the main cohort included children with cardiovascular events from the National Health Insurance Service database (2008-2012 births in Korea) until 2018. The second cohort excluded children with specific birth histories or underlying cardiovascular diseases from the main cohort. Cardiovascular events of interest included cardiac arrhythmia and ischemic heart disease. Odds ratios (ORs) of cardiovascular events were estimated using conditional logistic regression models, comparing first-generation H1-antihistamine use during 0-15 days before cardiovascular events (hazard period) with use during 45-60 and 75-90 days before events (control periods). Among the participants, 1194 (59.9%) were aged 24 months to 6 years, and 1010 (50.7%) were male. Cardiovascular event risk was increased among users of first-generation H1-antihistamines (adjusted OR [aOR], 1.201; 95% confidence interval, 1.13-1.27). Significant odds of cardiovascular events persisted within 10 and 5 days (aOR, 1.25 and 1.25). In the second cohort, the association was comparable with that in the main cohort. Our findings indicate that cardiovascular event risk is increased in children who are administered first-generation H1-antihistamines.

Rapid weight gain in early life is associated with central precocious puberty in girls, not in boys - a nationwide population-based study in Korea

Objectives

This study aimed to investigate the effect of rapid weight gain (RWG) on the incidence of central precocious puberty (CPP) using nationwide population-based data.

Methods

A total of 253,967 children (101,841 boys and 152,126 girls) who underwent regular health consultations under the National Health Insurance Service from 2007 to 2010 were followed up until the age of 10 years for boys and 9 years for girls. We calculated differences in the weight Z-scores from 4-6 months to 9-12 months (infancy) and from 9-12 months to 18-24 months or 30-36 months (toddlerhood) using the lambda-mu-sigma method. The population was subdivided into four groups: RWGinf/tod (infancy > + 0.67 standard deviation score [SDS], toddlerhood > 0 SDS), RWGinf (infancy > + 0.67 SDS, toddlerhood < 0 SDS), RWGtod (toddlerhood > + 0.67 SDS), and control (no RWG). The diagnosis of CPP was based on the diagnostic codes of the International Classification of Diseases 10th revision and the prescription of gonadotropin-releasing hormone agonists. The cumulative risk of CPP based on age was analyzed using Kaplan-Meier survival curves, and the association between the RWG groups and CPP was assessed using multivariate logistic regression analysis.

Results

CPP was diagnosed in 268 boys and 9,225 girls. For the girls, the CPP-free probability was the highest in the control group, followed by the RWGtod, RWGinf, and RWGinf/tod groups (log-rank p < 0.001). However, the incidence of CPP did not vary significantly for the boys. Compared to the control group, the other groups had a higher risk of CPP in girls (RWGinf/tod: adjusted odds ratio [aOR] 1.35, 95%, confidence interval [95% CI] 1.13-1.62; RWGinf: aOR 1.25, 95% CI 1.13-1.38; and RWGtod: aOR 1.18, 95% CI 1.09-1.28).

Conclusions

This nationwide population-based study demonstrated that any RWG from birth to 3 years of age contributed to an increased risk of CPP in girls but not in boys. Girls who experienced RWG during both infancy and toddlerhood had the highest risk of developing CPP. These findings suggest that early detection and appropriate management of excessive weight gain in early life may be important for preventing CPP in girls.

Infant Feeding Pattern Clusters Are Associated with Childhood Health Outcomes

(1) Background: Feeding behavior habits have a pattern with a certain tendency during infancy. We aimed to identify the associations between feeding patterns in infancy and the subsequent 10-year childhood disease burden. (2) Methods: Data from 236,372 infants were obtained from the national health insurance and screening program records in South Korea. Parent-administered questionnaires during infancy provided details on the feeding type and types/frequency of complementary food for analyzing feeding patterns. The outcomes were all-cause hospitalization and the development of 15 representative childhood diseases until the age of 10 years. Anthropometric measurements obtained at 6 years of age were analyzed. To estimate outcome risks while considering multiple risk factors, we employed a Cox proportional hazard and modified Poisson regression. (3) Results: Three clusters were identified: high prevalence of breastfeeding with regular exposure to a variety of solid foods (n = 116,372, cluster 1), similar prevalence of breastfeeding and formula feeding with less exposure to solid foods (n = 108,189, cluster 2), and similar prevalence of breastfeeding and formula feeding with the least exposure to solid foods in infancy (n = 11,811, cluster 3). Compared with cluster 1, children in clusters 2 and 3 had increased risks of all-cause hospitalization (hazard ratio (HR), (95% confidence interval (CI)), 1.04 (1.03-1.06) and 1.08 (1.05-1.11), respectively). Children in clusters 2 and 3 had an increased risk of upper respiratory infection, pneumonia, and gastroenteritis, as well as neurobehavioral diseases. Overweight/obesity at the age of 6 years was associated with clusters 2 and 3. (4) Conclusions: Feeding patterns in infancy were associated with an increased risk of childhood disease burden.

Association between atopic dermatitis and school readiness in preschool children

BACKGROUND

Although atopic dermatitis (AD) in children affects diverse stages of life, no studies have reported on the association between school readiness and AD.

METHODS

This study used Korean National Health Insurance data and the Health Screening Program for Infants and Children. Among all children born between 2008 and 2012 in Korea, those who were assessed for school readiness through questionnaires in a health screening program performed at 54 and 60 months old were enrolled. AD was defined based on the International Classification of Diseases codes, with two or more prescriptions of topical corticosteroids during the first 54-60 months of life. The primary outcome was the association between school readiness and AD. The questionnaire relating to school readiness comprised six items - cognitive skills, social development, activeness, concentration, emotional development, and language skills. Logistic regression analysis was used to identify the associations between school readiness and AD.

RESULTS

This study included 239,673 children without AD and 38,229 children with AD. The average age at which school readiness was assessed was 4.8 years. AD was associated with vulnerability in activeness (adjusted odds ratio: 1.127; 95% confidence interval: 1.071-1.186) and concentrations (1.170; 1.093-1.254). The impact of AD on concentrations showed consistent results regardless of sex, exposure to systemic corticosteroids and antihistamines, and age at the diagnosis of AD.

CONCLUSIONS

Children with AD have vulnerability in school readiness in the aspects of activeness and concentration.

Longitudinal study of multidimensional factors influencing maternal and offspring health outcomes: a study protocol

BACKGROUND

Reducing preventable adverse maternal and offspring outcomes is a global priority. The causes of adverse maternal and fetal outcomes are complex with multidimensional influencing factors. In addition, the Covid-19 epidemic has had a significant psychological and physical impact on people. China is now stepping into the post-epidemic era. We are curious about the psychological and physical situation of maternity in China at this stage. Therefore, we plan to initiate a prospective longitudinal study to investigate the multidimensional influences and mechanisms that affect maternal and offspring health.

METHOD

We will recruit eligible pregnant women at Renmin Hospital of Hubei Province, China. The expected sample size is 1490. We will assess socio-demographics, Covid-19 related information, social capital, sleep, mental health and medical records, including clinical examination and biochemical tests. Eligible pregnant women will be enrolled in the study with less than 14 weeks of gestation. Participants will receive a total of nine follow-up visits between mid-pregnancy and one year postpartum. The offspring will be followed up at birth, 6 weeks, 3 months, 6 months and one year. In addition, a qualitative study will be conducted to understand the underlying causes that affect maternal and offspring health outcomes.

DISCUSSION

This is the first longitudinal study of maternity in Wuhan, Hubei Province which integrates physical, psychological and social capital dimensions. Wuhan is the first city to be affected by Covid-19 in China. As China moves into the post-epidemic era, this study will provide us with a better understanding of the long-term impact of the epidemic on maternal and offspring health outcomes. We will implement a range of rigorous measures to enhance participants' retention rate and ensure the quality of data. The study will provide empirical results for maternal health in the post-epidemic era.

Survival of children with trisomy 18 associated with the presence of congenital heart disease and intervention in the Republic of Korea

BACKGROUND

Trisomy 18 syndrome (T18) is the second most common autosomal trisomy and has a high risk of fetal loss and stillbirth. Aggressive surgical treatments for the respiratory, cardiac, or digestive systems of patients with T18 were previously futile, while the results of recent studies are controversial. Over the past decade, there have been approximately 300,000 to 400,000 births annually in the Republic of Korea; however, there have been no nationwide studies on T18. This nationwide retrospective cohort study aimed to determine the prevalence of T18 in Korea and its prognosis according to the presence of congenital heart disease and relevant interventions.

METHODS

This study utilized NHIS-registered data between 2008 and 2017. A child was defined as having T18 if the ICD-10 revision code Q91.0-3 was reported. Subgroup analysis was performed for children with congenital heart diseases, and survival rates were compared based on the history of cardiac surgical or catheter interventions. The primary outcomes in this study were the survival rate during the first hospitalization period and the 1-year survival rate.

RESULTS

Of the children born between 2008 and 2017, 193 were diagnosed with T18. Of these, 86 died, with a median survival of 127 days. The 1-year survival rate for children with T18 was 63.2%. The survival rate in the first admission of children with T18 who did and did not have congenital heart disease was 58.3% and 94.1%, respectively. Children with heart disease who underwent surgical or catheter intervention had a longer survival time than those who did not.

CONCLUSIONS

We suggest these data could be used in ante- and postnatal counseling. Ethical concerns about the prolonged survival of children with T18 remain; however, the potential benefits of interventions for congenital heart disease in this population need further study.

Acquired susceptibility to autoimmune diseases in pediatric patients with Escherichia coli infection: A population-matched retrospective cohort study

BACKGROUND

Escherichia coli (E.coli) infection has been proposed to play an important role as an initial trigger in the development of autoimmunity via molecular mimicry. However, there has been no preliminary cohort study to establish the association of E.coli infection with autoimmune diseases. Therefore, we conducted a large scale, population-matched cohort study to determine the risk of autoimmune disease among patients with exposure to E.coli.

METHODS

Utilizing the National Health Insurance Service database, we retrospectively analyzed a total of 259,875 Korean children that consisted of 23,625 exposed and 236,250 unexposed persons from January 1, 2002 to December 31, 2017. The exposed cohort was defined as patients diagnosed with E.coli infection. Unexposed controls were matched by birth year and sex at a 1:10 ratio for each exposed patient, using incidence density sampling. The primary outcome was autoimmune disease development. We used the Cox model to estimate the risks of autoimmune diseases among patients diagnosed with E.coli infection.

RESULTS

Over a mean follow-up of 10 years, there were 1455 autoimmune disease cases among exposed patients (incidence rate, 63.6 per 10,000 person-years) and 11,646 autoimmune disease cases among unexposed persons (incidence rate, 50.4 per 10,000 person-years), with an adjusted hazard ratio (HR) of 1.254 (95% CI 1.187-1.325). E.coli infection was associated with increased risks of autoimmune diseases; Reactive arthritis, HR 1.487, 95% CI 1.131-1.956; Henoch Schönlein purpura, HR 1.265, 95% CI 1.050-1.524; Systemic lupus erythematosus, HR 1.838, 95% CI 1.165-2.898; Sjögren's syndrome, HR 2.002, 95% CI 1.342-2.987; IgA nephropathy, HR 1.613, 95% CI 1.388-1.874. Kaplan-Meier cumulative incidence curves also showed a significant association between E.coli infection and incident autoimmune disease (p < 0.0001). This relationship was not only independent of demographic variables, but also remained consistent across various sensitivity analyses. On the other hand, patients with longer hospital stay for E.coli infection were at a higher risk of autoimmune disease (p = 0.0003), and the risk of autoimmune disease also tended to increase, as the frequency of E.coli infection was higher. Moreover, the relative risk of autoimmune disease seemed to be attenuated by use of antibiotics and a history of intestinal infectious disease, but elevated by coexistence of other autoimmune diseases.

CONCLUSIONS

Our cohort study indicates that E.coli infection was significantly associated with increased susceptibility to autoimmune diseases, even after adjusting for different factors. Thus, among environmental factors, a previous history of E.coli infection could be a predisposing risk factor in the development of autoimmune diseases.

Association Between Receipt of General Anesthesia During Childhood and Attention Deficit Hyperactive Disorder and Neurodevelopment

BACKGROUND

There are inconsistent reports regarding the association between general anesthesia and adverse neurodevelopmental and behavioral disorders in children.

METHODS

This nationwide administrative cohort study included children born in Korea between 2008 and 2009, and followed until December 31, 2017. The cohort included 93,717 participants who received general anesthesia with endotracheal intubation (ETI) who were matched to unexposed subjects in a 1:1 ratio. General anesthesia was defined by National Health Insurance Service treatment codes with intratracheal anesthesia, and the index date was the first event of general anesthesia. The primary outcome was attention deficit hyperactive disorder (ADHD), which was defined as at least a principal diagnosis of 10th revision of the International Classification of Diseases code F90.X after the age of 72 months. Neurodevelopment, which was assessed using a developmental screening test (Korean-Ages and Stages Questionnaire [K-ASQ]), was a secondary outcome. The K-ASQ is performed annually from 1 to 6 years of age and consists of 5 domains. The association between general anesthesia and ADHD was estimated using a Cox hazard model, and its association with neurodevelopment was estimated using a generalized estimation equation, with control for multiple risk factors beyond 1 year after the index date.

RESULTS

The median age at the index date was 3.8 (95% confidence interval [CI], 1.7-5.8) years, and there were 57,625 (61.5%) men. During a mean follow-up period of 5 years, the incidence rate of ADHD was 42.6 and 27.7 per 10,000 person-years (PY) in the exposed and unexposed groups, respectively (absolute rate difference 14.9 [95% CI, 12.5-17.3] per 10,000 PY). Compared to the unexposed group, the exposed group had an increased risk of ADHD (adjusted hazard ratio, 1.41 [95% CI, 1.30-1.52]). In addition, a longer duration of anesthesia with ETI and more general anesthesia procedures with ETI were associated with greater risk of ADHD. General anesthesia with ETI was also associated with poorer results in the K-ASQ.

CONCLUSION

Administration of general anesthesia with ETI to children is associated with an increased risk of ADHD and poor results in a neurodevelopmental screening test.

Neurodevelopment at 6 years of age in children with atopic dermatitis

BACKGROUND

Few studies have reported an association between atopic dermatitis and cognitive impairment in children. Therefore, we evaluated the association between atopic dermatitis (AD) and neurodevelopmental dysfunction in children.

METHODS

We analyzed 2,395,966 children born between 2008 and 2012 in Korea. All data were acquired from the databases of the Korean National Health Insurance System. AD was defined as five or more diagnoses before age 24 months. The outcome was suspected neurodevelopmental dysfunction in the gross motor skill, fine motor skill, cognition, language, sociality, and self-care domains of the Korean Developmental Screening Test for Infants and Children at age 6 years. The positive control outcome was defined as attention deficit hyperactive disorder (ADHD). The associations were assessed using ordinal logistic regression, adjusting for asthma and allergic rhinitis.

RESULTS

Among the eligible children, 89,452 and 30,557 were allocated to the control and AD groups, respectively. In the weighted data, the AD group showed a higher risk of suspected neurodevelopmental dysfunction in the total score (weighted adjusted odds ratio [95% CI] 1.10 [1.05-1.16]), gross motor skills (1.14 [1.04-1.25]), and fine motor skills (1.15 [1.06-1.25]) than the control group. The AD with steroids or hospitalization groups showed an increased risk of suspected neurodevelopmental dysfunction. In addition, the AD group showed a significant association with mental retardation, psychological development disorder, and behavioral and emotional disorders as well as ADHD.

CONCLUSIONS

AD before age 2 years may be associated with an increased risk of neurodevelopmental dysfunction including gross and fine motor skills in the young childhood period.

Twelve-Year Trajectory of Disease Burden and Mortality by Obesity Level in Korea: Analysis of the National Health Insurance Service Database

INTRODUCTION

Despite increases in obesity prevalence, awareness of obesity as a disease requiring active treatment remains lacking in Korea. We investigated differences in medical problems and expenditures and mortality across obesity categories using 12-year data from the National Health Insurance Service.

MATERIALS AND METHODS

Individuals aged 40-79 years who underwent medical examinations during 2003-2004 (n = 415,201) were divided based on Asian body mass index (kg/m²) criteria: normal weight (18.5 to < 23.0, 36.4%), overweight (23.0 to < 25.0, 28.3%), obesity (25.0 to < 30.0, 32.5%), and severe obesity (≥ 30.0, 2.8%). Medical problems and expenditures were fitted to linear mixed models. Mortality was analyzed via Cox proportional-hazards model.

RESULTS

More severe obesity was associated with a higher rate of medical problems, relative to normal weight: coefficient = 0.31 (95% confidence interval [CI], 0.30-0.32) for overweight, 0.61 (0.60-0.61) for obesity, and 1.07 (1.04-1.09) for severe obesity. A similar association was observed for medical expenditure: coefficient = 8.85 (95%CI, 6.80-10.89) for overweight, 20.04 (18.07-22.01) for obesity, and 48.76 (43.66-53.86) for severe obesity. Relative to overweight participants, those with normal weight and severe obesity exhibited a higher mortality risk (hazard ratio [HR] 1.21 [95%CI, 1.18-1.25] for normal; 1.27 [1.19-1.36] for severe obesity). In age-specific analyses, mortality risk was the highest for participants with severe obesity, aged < 60 years (HR, 1.58 [95%CI, 1.41-1.77]).

CONCLUSION

Disease burden including medical problems and expenditure, and mortality in middle-aged adults, increased proportionally to the degrees of obesity. Health policies and medical systems aimed at reducing the burden of obesity may help reduce the burden of disease on society.

Growth pattern during early infancy, body mass index during childhood and childhood asthma

BACKGROUND

There is a lack of longitudinal studies of associations between growth from infancy to childhood and asthma development.

OBJECTIVE

The objective of the study was to investigate the effects of weight change during infancy, body mass index (BMI) and the interaction of these factors on the risk of childhood asthma.

METHODS

We enrolled children born in 2008 and 2009 at full-term and with normal birth weight. The weight change in infancy was grouped into slow, on-track and rapid. BMI status in childhood was stratified into low, normal and high groups and used as a time-varying variable. The outcome was asthma, defined as two or more diagnoses of asthma separated by at least 1 year after 2 years of age. The risk of asthma was assessed using Cox proportional hazard regression, with adjustment for sex, residence area at birth, economic status and feeding types in infancy.

RESULTS

Of 917,707 children born in Korea in 2008 and 2009, 271,871 were eligible for analysis. The risk of asthma was greater in groups with low birth weight (aHR 1.06, 95% CI 1.04 to 1.08), rapid body weight change during early infancy (aHR 1.08, 95% CI 1.07 to 1.10) and high BMI during childhood (aHR 1.06, 95% CI 1.04-1.08). The interaction of weight change during early infancy with BMI during childhood was significant for asthma (p < .01). Rapid weight gain in infancy was associated with lower risk of asthma in those with low BMI during childhood; had no association with asthma in those with normal BMI during childhood; and was associated increased asthma risk in those with high BMI during childhood-aHR 1.26 (95% CI 1.19 to 1.33) and aHR 1.33 (95% CI 1.12 to 1.56) compared with on-track and slow infant weight gain, respectively.

CONCLUSION

Low birth weight, high BMI during childhood and, in those with high childhood BMI, rapid weight gain during early infancy are associated with increased risk of childhood asthma.

Relationship Between Feeding to Sleep During Infancy and Subsequent Childhood Disease Burden

OBJECTIVE

To investigate the association of feeding to sleep during infancy and subsequent childhood health burdens.

STUDY DESIGN

Information was collected from the parents of children who participated in the national health screening survey when the child was 9-12 months old. The exposure group included participants who were fed to sleep. The primary outcome was all-cause hospital admission (inpatient care, intensive care unit [ICU] admission, or general anesthesia) after age 24 months. Secondary outcomes were subsequent childhood diseases (ie, adenoidectomy and/or tonsillectomy, nasal polyps, allergic rhinitis, acute otitis media, asthma, pneumonia, and aspiration pneumonia), and growth status, as measured by weight-to-age and height-to-age z-scores.

RESULTS

The study cohort consisted of 224 075 children who participated in the health screening program, 29 392 of whom (13.1%; 51% males) were fed to sleep. Exposure was associated with an increased risk of all-cause hospitalization after age 24 months (hazard ratio [HR], 1.05; 95% CI, 1.03-1.07), but not with admission to an ICU or receipt of general anesthesia. This also was related to adenoidectomy and/or tonsillectomy (HR, 1.08; 95% CI, 1.01-1.15), dental caries (HR, 1.32; 95% CI, 1.23-1.40), asthma (HR, 1.14; 95% CI, 1.14-1.24), pneumonia (HR, 1.10; 95% CI, 1.07-1.13), overweight (HR, 1.06; 95% CI, 1.03-1.09), and obesity (HR, 1.11; 95% CI, 1.06-1.16).

CONCLUSIONS

Several adverse health outcomes are related to feeding to sleep during early childhood.

Infantile Colic and the Subsequent Development of the Irritable Bowel Syndrome

Background/Aims

Little is known about the association between infantile colic and the later onset of irritable bowel syndrome (IBS).

Methods

This study examined all 917 707 children who were born in Korea between 2007 and 2008. Infantile colic was defined with 1 or more diagnoses of ICD-10 code R10.4 or R68.1 at the age of 5 weeks to 4 months, and infants with a diagnosis of infantile colic and without were allocated into the infantile colic group and the control group. IBS was defined as 2 or more diagnoses of ICD-10 code K58.X after 4 years of age. Each child was traced until 2017. The risk of IBS with infantile colic was evaluated using a Cox proportional hazards model with propensity score inverse probability of treatment weighting (IPTW).

Results

After IPTW, 363 528 and 359 842 children were allocated to the control group and the infantile colic group, respectively. The infantile colic group had a higher risk of developing IBS in childhood (hazard ratio [95% CI], 1.12 [1.10 to 1.13]) than the control group. Moreover, the subgroup analyses according to the feeding status, birth weight, sex, or economic status, showed that the risk of IBS with former infantile colic remained statistically significant.

Conclusions

Children with a diagnosis of infantile colic during the infant period had a significant risk of developing IBS after 4 years of age. Understanding the pathogenesis of infantile colic in the neonatal period may reduce the prevalence and severity of functional gastrointestinal disorders from childhood to adolescence to adulthood.

Long-Term Observational Outcomes after Total Correction of Congenital Heart Disease in Korean Patients with Down Syndrome: A National Cohort Study

Background: In the present study, the population prevalence and postoperative morbidity and mortality in Down syndrome patients who underwent total correction for congenital heart disease were investigated using data from a large national cohort. Methods: Retrospective administrative data from 2,395,966 participants born between 2008 and 2012 were acquired from the National Investigation of Birth Cohort in Korea. Among Down syndrome patients, 58.3% had congenital heart disease and 32.3% underwent total correction. Propensity score matching (maximum 1:1) and stabilized inverse probability treatment weighting (IPTW) were performed for each group (153 Down syndrome patients and 4482 non-Down syndrome patients). Results: T late mortality rate was significantly higher in the Down syndrome group than in the non-Down syndrome group (8.1% vs. 3.8%). No differences were observed in postoperative heart failure and arrhythmias, but pulmonary hypertension was significantly greater in the Down syndrome group than in the non-Down syndrome group (26.9% vs. 7.0%). The length of hospitalization was longer in the Down syndrome group than in the non-Down syndrome group (14 days vs. 11 days; interquartile range (IQR): 10−25 vs. 6−19; p < 0.0001). After total correction, readmission frequency for any reason was minimally but statistically significantly higher in the Down syndrome group compared to the non-Down syndrome group (5 times vs. 5 times; IQR: 3−8 vs. 4−9; p < 0.0001). However, the number of emergency room visits was minimally but significantly lower in the Down syndrome group compared to the non-Down syndrome group (2 visits vs. 2 visits (IQR): 2−7 vs. 1−4; p = 0.016). Conclusions: Down syndrome patients with congenital heart disease undergoing total correction showed pulmonary hypertension after surgery, longer length of hospitalization, frequent hospitalization after surgery, and a higher rate of late mortality.

Association of Familial History of Diabetes, Hypertension, Dyslipidemia, Stroke, or Myocardial Infarction With Risk of Kawasaki Disease

Background

There are few studies on the association with Kawasaki disease in children and the family’s history of cardiovascular disease (CVD). The aim of this study was to identify the association of increased risks for Kawasaki disease in children with a family history of CVD.

Methods and Results

Clinical data of children born in 2008 and 2009 (n=917 707) were obtained from the National Health Insurance Service and the National Health Screening Program for Infants and Children for this study. The cohort consisted of 495 215 participants (53.8%) who completed the family history questionnaire for children 54 to 60 months old. Family history of CVD included 5 medical conditions: hypertension, dyslipidemia, myocardial infarction, stroke, and diabetes. Kawasaki disease was defined using the disease code, intravenous immunoglobulin prescription, and use of antipyretics for more than 25 days. Severe Kawasaki disease was defined as diagnosis of accompanied cardiac/coronary artery complications or intravenous immunoglobulin use ≥2 times. The incidence rate of Kawasaki disease was 124/100 000 person‐years (95% CI, 117.5–131.5) for children <2 years old, 95/100 000 person‐years (95% CI, 90.5–100.4) in children 2 to 5 years old, and 14/100 000 person‐years (95% CI, 12.6–15.6) in children >5 years old. After propensity‐score matching, 829 participants with a family history of CVD were diagnosed as having Kawasaki disease (0.68% [95% CI, 0.63–0.72]), and 690 patients with Kawasaki disease (0.56% [95% CI, 0.52–0.61]) had no family history of CVD. The family history of CVD was associated with increased risk for Kawasaki disease (risk ratio, 1.20 [95% CI, 1.08–1.32]) but not for severe Kawasaki disease (risk ratio, 1.23 [95% CI, 0.92–1.65]).

Conclusions

In this nationwide propensity‐score matched study, those with a family history of CVD had a significantly greater risk of Kawasaki disease compared with those who had no family history of CVD.

Effect of parental supervision of infants at age 4 to 6 months on injuries at age 4 to 12 months

This study analyzed the effect of parental supervision of infants at age 4 to 6 months on injuries at age 4 to 12 months. Among all Korean children born during 2008-2009, 464,326 (50.6%) infant had parents who responded to a questionnaire that surveyed their safety and supervision when infant were 4 to 6 months-old. Based on questionnaire score, infant were divided into "safe" or "unsafe" group. 1:1 propensity score matching was used to balance the groups, and injury diagnosis and treatments were analyzed. After matching, we examined the records of 405,862 infant. The unsafe group had significantly increased risk ratios (RRs) for injury of head/neck (RR: 1.06), trunk/abdominopelvic region (RR: 1.12), upper extremities (RR: 1.04), and from burn and frostbite (RR: 1.10). The risks of a wound and fracture and foreign body injury were significantly greater in infant whose parents sometimes left them alone (RR: 1.15 and 1.06, respectively), and whose parents did not always keep their eyes on them (RR: 1.04 and 1.13, respectively). Infant whose parents had a hot drink when carrying them had an increased risk of burn injuries (RR: 1.21). Injuries were less common in infant whose parents provided more supervision.

Neurodevelopmental outcomes and comorbidities of children with congenital muscular torticollis: evaluation using the National Health Screening Program for Infants and Children database

BACKGROUND

Congenital muscular torticollis (CMT) is a common musculoskeletal disorder occurring at birth or in infancy.

PURPOSE

This study aimed to investigate the risk of comorbidities in CMT and explore the differences in neurodevelopmental outcomes between children who received physical therapy and those who did not.

METHODS

Children with CMT born in 2008 and 2009 in Korea were included. CMT was defined as a primary diagnosis of congenital deformity of sternocleidomastoid muscle according to the International Classification of Diseases 10th revision. Here we investigated the associated neurological/musculoskeletal comorbidities of children with CMT versus those of the general population. We divided those with torticollis into treatment and nontreatment groups and assessed their developmental outcomes within both groups of children using the Korean-Ages and Stages Questionnaire (K-ASQ).

RESULTS

Of the 917,707 children, 0.2% (n=1,719) were diagnosed with CMT. In children with torticollis, the prevalence of congenital hip deformities significantly increased to 4.5% (n=78). The prevalence of congenital head/spine deformities and other congenital malformations of the skull and facial bones increased to 2.6% (n=44), while the prevalence of congenital foot deformities was 2.4% (n=42). The risk ratio (RR) for delayed development based on the K-ASQ was higher for the total assessment (adjusted RR=0.97; 95% confidence interval, 0.93-0.99) in the CMT patients without physical therapy than in those with therapy. There was no significant intergroup difference in the assessment of each developmental area.

CONCLUSION

The prevalence of comorbid musculoskeletal deformities was higher in children with CMT than in the control group. The risk of developmental delay was higher in children who did not receive physical therapy than in those who did.

A nationwide cohort study on the risk of ADHD in children with amblyopia mediated by fine motor skill impairment in East Asia

This national administrative investigation of Republic of Korea compared the risk of attention deficit hyperactivity disorder (ADHD) and autism spectrum disorders(ASD) in preschool amblyopic children and identified factors that possibly mediate this association. After propensity score (PS) matching, 7762 amblyopic children and 31,030 non-amblyopic children were included. Amblyopia was associated with ADHD (aOR:1.687; 95% CI 1.444, 1.970) but not with ASD (aOR: 0.591; 95% CI 0.341, 1.026). Fine motor skill impairment was a mediating factor in association of amblyopia with ADHD, accounting for 4.2% (95% CI 1.7, 8.0). In conclusion, amblyopic children have a greater risk of ADHD, and deficits in fine motor skills mediate this association. We suggest increased attention given to fine motor skill underdevelopment in amblyopic children to prevent the development of ADHD.

Association of Antibiotic Use during the First 6 Months of Life with Body Mass of Children

In this study, our objective was to assess the association of body mass in preschool children with the use of antibiotics within 6 months after birth. National administrative databases were used to examine all children born between 2008 and 2009 in Korea. Exposure was defined as the use of systemic antibiotics during the first 6 months of age. The observed outcomes were stunting (height for age [HFA] z score < −2.0), short stature (HFA z score < −1.64), overweight (body mass index [BMI] for age z score ≥ 1.04), and obesity (BMI for age z score ≥ 1.64), and the children’s height and body weight were measured from three to six years of age. To balance characteristics between the antibiotic user and non-user groups, propensity score matching was performed. The outcomes were evaluated using a generalized estimation equation with the logit link function. Analysis of antibiotic use by children during the first 6 months of life indicated there were 203,073 users (54.9%) and 166,505 non-users (45.1%). After PS matching, there were 72,983 antibiotic users and 72,983 non-users. Antibiotic use was significantly associated with stunting (aOR = 1.198, 95% CI = 1.056 to 1.360) and short stature (aOR = 1.043, 95% CI = 1.004 to 1.083), and had significant negative association with HFA z score (weighted β = −0.023). The use of an antibiotic for 14 days or more had a marked association with stunting. Antibiotic use was also associated with overweight, obesity, and increased BMI for age z score. Antibiotic use during the first 6 months of life increased the risk of stunting, short stature, overweight, and obesity in preschool children.

Risk Factors for Obesity in Five-Year-Old Children: Based on Korean National Health Insurance Service (NHIS) Data

This study aimed to identify the risk factors for obesity in five-year-old children using data from the database of the Korean National Health Insurance Service. We identified 26,047 children who underwent the sixth screening (at age 5) from the 2017 National Health Screening Program for Infant and Children and for whom data from the fourth screening (at age 3) database and the mothers’ health screening and eligibility database were available. To identify the risk factors of obesity, odds ratios and 95% confidence intervals were calculated by a hierarchical multiple logistic regression. Female sex, a birth weight of over 4 kg, the “caution/refer” remark during developmental screening at ages three and five, maternal obesity, and a middle-level income were risk factors for obesity in the subjects. Good appetite, high consumption of milk, heavy intake of sweet food at age three, speedy eating, irregular meals and snack times, large single-meal quantities, heavy intake of oily and salty food, and not performing physical exercise at age five were also considered significant risk factors. For early intervention efforts to prevent childhood obesity, modifiable behavioral factors and other obesity risk factors identified in this study could be used to target high-risk children and dietary behaviors.

Association between birth weight and neurodevelopmental disorders assessed using the Korean National Health Insurance Service claims data

The risk of neurodevelopmental disorders in low birth weight (LBW) infants has gained recognition but remains debatable. We investigated the risk of attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) in school-aged children according to their birth weight. We conducted a retrospective cohort study using the Korean National Health Insurance claims data of 2,143,652 children who were born between 2008 and 2012. Gestational age of infants was not available; thus, outcomes were not adjusted with it. Not only infants with birth weights of < 1.5 kg, but also 2.0–2.4 kg and 1.5–1.9 kg were associated with having ADHD; odds ratio (OR), 1.41 (95% confidence interval [CI] 1.33–1.50), and 1.49 (95% CI 1.33–1.66), respectively. The OR in infants with birth weights of 2.0–2.4 kg and 1.5–1.9 kg was 1.91 (95% CI 1.79–2.05) and 3.25 (95% CI 2.95–3.59), respectively, indicating increased odds of having ASD. Subgroup analysis for children without perinatal diseases showed similar results. In this national cohort, infants with birth weights of < 2.5 kg were associated with ADHD and ASD, regardless of perinatal history. Children born with LBW need detailed clinical follow-up.

Association of clinical and social factors with risk of fracture in children with atopic dermatitis

BACKGROUND

Children with atopic dermatitis (AD) have multiple risk factors for accidental fractures, injuries that can lead to significant morbidity and mortality. However, little is known about the factors that mediate the relationship between AD and fracture in children.

OBJECTIVE

Our purpose was to examine the association of AD with fracture and to identify potential mediating factors.

METHODS

This retrospective cohort study examined children with and without AD from a longitudinal matched cohort database of 353,040 children registered in the national health insurance service and participated in the national health-screening program of Korea. We defined AD using medical claims and medication prescription records. We investigated accidental fracture events between the index date and the end of follow-up in a propensity score-matched cohort. Pre-specified subgroup analyses considered fractures in four different regions of the body. The mediating effects of 10 possible clinical factors (including the use of antihistamines and systemic corticosteroids) and social factors (including nutritional status and parental safety awareness) were determined.

RESULTS

There were 145,704 participating children, 20% with AD and 49% girls. Fractures occurred in 6,652 of the children with AD (23%, mean age: 64.6 ± 29.2 months) and in 24,698 of the control group (21%, mean age 65.0 ± 28.9 months). Children with AD had an 8% greater risk of fracture events overall (adjusted relative risk [aRR]: 1.08, 95% CI: 1.05-1.10). In subgroup analysis, AD was related to increased rates of skull and facial bone fracture (aRR: 1.09, 95% CI: 1.04-1.14), for trunk including vertebrae (aRR: 1.58, 95% CI: 1.22- 2.05), and for distal limbs (aRR: 1.11, 95% CI: 1.07-1.15). However, the relationship with proximal limb fracture was insignificant. Duration of systemic corticosteroid prescription was the largest mediating factor, followed by duration of antihistamine prescription, and infant feeding practices. In particular, the duration of systemic corticosteroid prescription was significantly associated with fracture events (incidence: 20.1% at the 25th percentile and 23.6% at the 75th percentile; difference: 3.4% [95% CI: 2.8-4.0%]).

CONCLUSIONS

Children with AD were related to increased fracture events. The key factors with mediating effects were systemic use of corticosteroid and antihistamine. Infant feeding practices had weaker mediating effects.

Association of Consuming Tap Water or Purified Water during Infancy with Irritable Bowel Syndrome in Children

Objective: The objective of this study was to analyze the effect of consuming formula powder prepared with tap water or purified water during the first 4 to 6 months of life on the subsequent development of irritable bowel syndrome (IBS). Study design and setting: A total of 917,707 children who were born in Korea between 2007 and 2008 were analyzed. All children were followed up until they lost eligibility for health care services or until 2017. Data on the water used to prepare formula powder were from questionnaires answered by the parents when the child was 4 to 6 months old. IBS was defined as two or more diagnoses of IBS after the age of 4 years. Inverse probability of treatment weighting (IPTW) using the propensity score was used to balance the two groups. The risk of IBS was evaluated using a Cox proportional hazards model. Results: After weighting, there were 73,355 children in the tap water group and 73,351 in the purified water group. The purified water group had a higher risk of IBS (HR: 1.05; 95% CI: 1.01, 1.09). This relationship was also present after the subgroup analyses of males and females and the sensitivity analysis that used different definitions of IBS. Conclusions: Drinking formula powder prepared with purified water rather than tap water during the first 4 to 6 months of age was found to be associated with IBS.

Changes in childhood growth after adenotonsillectomy: a population-based cohort study

OBJECTIVES

This study aimed to investigate the association between adenotonsillectomy (T&A) and serial changes in growth in children through a population-based nationwide study as well as the national health insurance service (NHIS) database.

METHODS

Propensity score (PS) matched children with and without T&A were selected in NHIS database, which includes all individuals born in Korea in 2008-2009. Serial changes of BMI and height were compared in children with and without T&A, and growth changes depending on the time of operation were also considered. The outcomes were differences in age-/sex-standardized BMI (BMI-z) and height (height-z) between the groups. Changes in BMI-z and height-z were further analyzed according to the timing of operation.

RESULTS

Of 919,707 individuals born in Korea in 2008-2009, 3172 children were included in the operation group and 31,663 PS-matched children were included in the control group. T&A was related to increased weight and height in the operation group than in the control group. At 66-71 months of age, BMI-z and height-z were 0.41 (0.02) and 0.42 (0.02), respectively, in the operation group and 0.18 (0.01) and 0.35 (0.01), respectively, in the control group. On adjustment with preoperative BMI-z, more weight gain was noted in the operation group (p < 0.001). Shortly after T&A, BMI-z increased significantly in the operation group; a significant increase in height-z was observed more than 1 year after T&A.

CONCLUSIONS

Children who underwent T&A tended to experience a growth spurt; when surgical intervention such as T&A is required, care should be taken to minimize or reverse the anticipated weight gain.

Is High Milk Intake Good for Children's Health? A National Population-Based Observational Cohort Study

Milk is widely considered as a beneficial product for growing children. This study was designed to describe the milk consumption status of Korean children aged 30–36 months and to investigate its association with the risk of obesity and iron deficiency anemia (IDA). This nationwide administrative study used data from the Korean national health insurance system and child health screening examinations for children born in 2008 and 2009. In total, 425,583 children were included, and they were divided into three groups based on daily milk consumption: low milk group (do not drink or drink <200 mL milk per day, n = 139,659), reference group (drink 200–499 mL milk per day, n = 255,670), and high milk group (drink ≥500 mL milk per day, n = 30,254). After adjusting variable confounding factors, the consumption of a large amount of milk of ≥500 mL per day at the age of 30–36 months was associated with an increased risk of obesity at the age of 42–72 months and IDA after the age of 30 months. These results may provide partial evidence for dietary guidelines for milk consumption in children that are conducive to health.

Neurodevelopmental Outcomes in Infants Fed with Soy Formula: A Retrospective, National Population-Based Observational Cohort Study

BACKGROUND

Soy-based infant formulas are increasingly popular, but data regarding their effects on neurodevelopmental outcomes during early childhood is scanty.

OBJECTIVE

This study investigated the effect of consuming soy-based infant formula at 9-12 mo after birth on the subsequent development of epilepsy, neurodevelopmental disorders, and developmental status.

METHODS

This nationwide retrospective administrative study used health screening examinations and linked insurance claims data of children born in Korea during 2008 and 2009. Infants who received soy formula were compared with those who received cow's milk formula using propensity score matching that considered birth history, economic status, clinical conditions, and drug prescription records. Exposure was defined as soy formula feeding determined from questionnaires completed by the parents when children were 9-12 mo old. Outcomes were epilepsy, attention-deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and developmental status. Children were followed until 31 December, 2017.

RESULTS

A total of 153,841 eligible participants were enrolled; 11,535 (7.5%) children received soy formula, while 142,864 (92.5%) received cow's milk formula. The incidence rate of epilepsy during the follow-up period was 29.8 per 100,000 person-years (95% CI: 19.48, 41.65) in the soy formula group and 22.6 per 100,000 person-years (95% CI: 31.97, 59.07) in the cow's milk formula group, with no significant difference (aHR: 1.318; 95% CI: 0.825, 2.106). The 2 groups also had no difference based on prespecified analysis using different definitions of epilepsy. Likewise, no significant associations of soy formula with ADHD (aHR: 1.26; 95% CI: 1.00, 1.60) or ASD (aHR: 0.99; 95% CI: 0.54, 1.83), or delays of developmental stages were observed.

CONCLUSIONS

Feeding with soy formula rather than cow's milk formula had no apparent association with increased risks of epilepsy, ADHD, ASD, and developmental status, according to this cohort composed of a general pediatric population.

Breastmilk Feeding during the First 4 to 6 Months of Age and Childhood Disease Burden until 10 Years of Age

BACKGROUND

Breastfeeding is recommended due to its beneficial effects on human health. However, the effect of breastfeeding on health differs, resulting in various childhood diseases.

OBJECTIVE

Our purpose was to investigate the association between breastfeeding at least in the first 4 months and the subsequent development of 15 certainly defined childhood diseases until 10 years of age, the all-cause hospitalization rate and growth at 6-7 years of age.

METHODS

Participants included propensity-score matched 188,052 children born between January 2008 and December 2009, who were followed up till 10 years of age. Data were taken from the National Investigation of birth Cohort in Korea study 2008 database. Risk ratios were obtained using a modified Poisson regression and weighted risk differences using binomial regression.

RESULTS

Compared to formula feeding, breastfeeding was associated with decreased risks of febrile convulsion, attention deficit hyperactivity disorder and autism spectrum disorder, pneumonia, acute bronchiolitis, hypertrophic pyloric stenosis, asthma, all-cause hospitalization, overweight/obesity and short stature. Exclusive breastfeeding at 4 to 6 months of age had similar results to exclusive breastfeeding over 6 months of age.

CONCLUSIONS

Breastfeeding in early infancy reduces the risk for various childhood diseases, all-cause hospitalization rate, obesity, and short stature during childhood.