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Abstract Objective To analyze the complex relationship between socioeconomic status (SES) and neurodevelopmental achievements by investigating the temporal dynamics of these associations from birth to age 6. Methods This retrospective cohort study was conducted over 6 years using population-based data from the National Health Insurance Service and integrated data from the National Health Screening Program for Infants and Children. Participants were children born between 2009 and 2011 in Korea without neurodevelopmental delays with potential developmental implications. We analyzed results from the Korean Developmental Screening Test, administered at age 6, which covered overall assessment and six domains of gross and fine motor function, cognition, language, sociality, and self-care. The secondary outcome was to determine when neurodevelopmental outcomes began after birth and how these differences changed over time. Results Of 276,167 individuals (49.2% males), 66,325, 138,980, and 60,862 had low, intermediate, and high SES, respectively. Neurodevelopmental delays observed across all developmental domains were more prevalent in the low-SES group than in the high-SES group. Disparities in neurodevelopment according to these statuses were apparent as early as age 2 and tended to increase over time (interaction, P

Background Acute bronchiolitis is a common cause of hospitalization during infancy that carries significant morbidity and mortality rates. Purpose This study compared the efficacy of different treatment modalities for infants with bronchiolitis in terms of hospital stay and clinical severity scores. Methods The PubMed database was searched for relevant studies. Eligibility criteria included double-blind randomized controlled trial design, assessment of the effect of treatment on bronchiolitis in infants under 2 years of age, and publication in English from inception through July 31, 2020. The primary efficacy outcome was the length of hospital stay, while the secondary outcome was the clinical severity score. The standardized treatment effect and standard error of the effect size were calculated. Results We identified 45 randomized controlled trials of 24 pairwise comparisons. These 45 trials included 5,061 participants and investigated 13 types of interventions (12 active, 1 placebo). Inhalation therapy with epinephrine (standard mean difference [SMD], -0.41; 95% confidence interval [CI], -0.8 to -0.03) and hypertonic saline (SMD, -0.29; 95% CI, -0.55 to -0.03) reduced the length of hospital stay compared with normal saline. Hypertonic saline was the most effective at improving the clinical severity score (SMD, -0.52; 95% CI, -0.95 to -0.10). Conclusion Inhalation therapy with epinephrine and hypertonic saline reduced the length of hospital stay and the clinical severity of bronchiolitis among infants under 2 years of age.

Background: Understanding the trends of anaphylaxis and risk factors associated with its recurrence is essential for the effective management and prevention of this condition. Objective: This study aimed to analyze the prevalence trends of anaphylaxis and identify risk factors for recurrence, with a focus on the influence of neighborhood deprivation and comorbidities, across all age groups. Methods: We conducted a retrospective administrative cohort study on anaphylaxis utilizing the National Health Insurance-National Sample Cohort (NHIS-NSC) database in Korea (2002–2019). Anaphylaxis was defined with ICD-10 codes for the diagnosis combined with prescription codes. The Neighborhood Deprivation Index was used to identify the risk of recurrent anaphylaxis. Trends in the annual prevalence and recurrence of anaphylaxis were assessed through joinpoint regression and Cox proportional hazard models. Results: Out of the 1,137,861 individuals studied, 37,012 (3.25%) cases of anaphylaxis were identified. Among these, 5783 individuals (15.6%) experienced a recurrence, half of them experiencing it within the first year after the initial episode. The highest incidence of anaphylaxis was observed in children and adolescents, followed by middle-aged adults. A rapid increase in anaphylaxis cases was observed from 2002 to 2006 (Annual Percentage Change [APC], 33.2), followed by a more gradual increase until 2013 (APC, 12.8), and a stable trend from 2013 to 2019 (APC, 0.61). Males and adult age groups exhibited an increased risk of recurrence. Living in an area with neighborhood deprivation and the presence of comorbid conditions were associated with increased recurrence risk. Conclusions: The increasing prevalence of anaphylaxis and its association with certain risk factors calls for targeted intervention. Addressing neighborhood deprivation and comorbid conditions may aid in reducing the recurrence and overall burden of anaphylaxis.

Background: Periostin and human chitinase-3-like protein 1 (YKL-40) have been suggested to be involved in the development of airway fibrosis and remodeling. This study aimed to investigate the relationship between serum periostin levels and airway hyperresponsiveness (AHR) and between serum YKL-40 levels and AHR in children with asthma, comparing periostin as a marker for Th2 inflammation and atopy with YKL-40. Methods: The study involved children aged 6–15 years, comprising 75 with asthma and 29 healthy controls. We measured serum periostin and YKL-40 levels and performed exercise bronchial provocation tests, methacholine challenge tests, spirometry, and FeNO measurements. Results: Compared to the healthy controls, asthmatic children exhibited significantly elevated levels of periostin (86.7 [71.0–104.0] vs 68.3 [56.0–82.0] ng/mL; P = 0.006) and YKL-40 (29.0 [15.0–39.5] vs 27.7 [14.0–34.1] ng/mL; P = 0.034). The subgroup analysis revealed that periostin levels were significantly higher in the atopic asthma group than in the healthy controls (P = 0.003), but not in the non-atopic asthma group. YKL-40 levels were elevated in both the atopic and non-atopic asthma groups compared to healthy controls (P = 0.012 and P = 0.001, respectively). Serum periostin levels were significantly correlated with the postexerceise maximum percentage decrease in forced expiratory volume (FEV1), as well as with fractional exhaled nitric oxide (FeNO) and blood eosinophil counts, but showed no significant correlation with overall lung function. Conversely, serum YKL-40 levels were significantly linked to the Z score of FEV1 and AHR to methacholine but not with AHR to exercise or FeNO or blood eosinophil count. Conclusions: Periostin is linked to atopic asthma and correlates with exercise-induced bronchoconstriction, FeNO, and eosinophil counts, highlighting its role in Th2 inflammation. YKL-40 is a general asthma marker, indicating airway remodeling. These findings suggest that targeting these markers can improve personalized treatment strategies for pediatric asthma.

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.

Abstract The cohort consisted of 9400 exposed children diagnosed with ventricular septal defect (VSD). The risk of community-acquired pneumonia (CAP) or asthma with VSD was assessed using the Cox proportional hazard model with an inverse probability of treatment weighting. During a mean follow-up of 6.67 years (starting from 12 months after birth), there were 2100 CAP admission cases among exposed patients (incidence rate: 33.2 per 1000 person-years) and 20,109 CAP admission cases among unexposed children (incidence rate: 29.6 per 1000 person-years), with hazard ration of 1.09 (95% CI 1.04–1.14).

Long coronavirus disease (COVID), also known as postacute sequelae of severe acute respiratory syndrome coronavirus 2 infection, has been defined as signs and symptoms which persist for 4 weeks or even lasting for 6 months after the initial infection. Although the prevalence of long COVID in children is currently unknown, epidemiological investigations have reported cases in pediatric populations. Clinical manifestations of long COVID in children include respiratory symptoms, such as cough and dyspnea, as well as neuropsychiatric and general conditions, including fatigue, headache, and muscle weakness. The pathophysiology of long COVID in children is still being investigated, but potential mechanisms include viral persistence, autoimmunity, and neuroinflammation. Risk factors for long COVID in children are not yet well understood, but studies have suggested that children with a history of severe acute COVID-19 infection or comorbidities may be at increased risk. Evaluation for respiratory symptoms of long COVID in children is essential, including spirometry and imaging studies to assess lung function and any potential damage. Furthermore, long COVID in children has been associated with a higher prevalence of mental health problems than in adults, emphasizing the importance of monitoring and addressing these aspects in pediatric patients. Although our understanding of long COVID in children and adolescents is still evolving, it is clear that the condition can have significant impacts on their health and well-being. The aim of this review is to synthesize the current knowledge on the prevalence, risk factors, and pathophysiology of long COVID in children and adolescents, and to discuss potential management strategies based on existing evidence.

Background The association between dyslipidemia and asthma in children remains unclear. Purpose This study investigated the association between dyslipidemia and cholesterol levels in children. Methods A systematic literature review was performed to identify studies investigating the association between dyslipidemia and asthma in children. The PubMed database was searched for articles published from January 2000–March 2022. Data from a cohort study using electronic health records from 5 hospitals, converted to the Observational Medical Outcomes Partnership Common Data Model (OMOP-CDM), were used to identify the association between total cholesterol (TC) levels and asthma in children. This cohort study used the Cox proportional hazards model to examine hazard ratio (HR) of asthma after propensity score matching, and included an aggregate meta-analysis of HR. Results We examined 11 studies reporting an association between dyslipidemia and asthma in children. Most were cross-sectional; however, their results were inconsistent. In OMOP-CDM multicenter analysis, the high TC (>170 mg/dL) group included 29,038 children, while the normal TC (≤170 mg/dL) group included 88,823 children including all hospital datasets. In a meta-analysis of this multicenter cohort, a significant association was found between high TC levels and later development of asthma in children

BackgroundMycoplasma pneumoniae infection is common in the general population and may be followed by immune dysfunction, but links with subsequent autoimmune disease remain inconclusive.ObjectiveTo estimate the association of M. pneumoniae infection with the risk of subsequent autoimmune disease.MethodsThis 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.ResultsThe 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).ConclusionM. pneumoniae infection requiring hospitalization may be associated with an increase in subsequent diagnoses of autoimmune diseases.

Background Human coronaviruses (HCoV) cause mild upper respiratory infections; however, in 2019, a novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged, causing an acute respiratory disease pandemic. Coronaviruses exhibit marked epidemiological and clinical differences. Purpose This study compared the clinical, laboratory, and radiographic findings of children infected with SARS-CoV-2 versus HCoV. Methods SARS-CoV-2 data were obtained from the Korea Disease Control and Prevention Agency (KDCA) registry and 4 dedicated coronavirus disease 2019 (COVID-19) hospitals. Medical records of children admitted with a single HCoV infection from January 2015 to March 2020 were collected from 10 secondary/tertiary hospitals. Clinical data included age, sex, underlying disease, symptoms, test results, imaging findings, treatment, and length of hospital stay. Results We compared the clinical characteristics of children infected with HCoV (n=475) to those of children infected with SARS-CoV-2 (272 from KDCA, 218 from COVID-19 hospitals). HCoV patients were younger than KDCA patients (older than 9 years:3.6% vs. 75.7%; P

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.

Abstract Introduction Macrolide‐resistant Mycoplasma pneumoniae (MRMP) has become prevalent in children. This study investigated the clinical and laboratory variables of MRMP and macrolide‐sensitive M. pneumoniae (MSMP) and identified factors associated with prolonged hospital admission in children. Methods A prospective multicenter study was conducted in 1063 children

Purpose Teenagers’ sleep patterns show physiological delays influenced by sexual maturation and other external time-related factors. However, Korean adolescents show differences in the onset of pubertal development and have shorter sleep durations than other adolescents worldwide. Therefore, we assessed sleep patterns and sexual maturation in Korean early adolescents to evaluate changes in sleep patterns in relation to sexual maturation in early adolescents with sleep deprivation. Methods From March to August 2017, we surveyed children aged 10 to 12 years in Seongnam (Seongnam Atopy Project). We evaluated items related to sleep and sexual maturation, assessed sleep duration and sleepiness scale scores, and analyzed the relationships of sleep parameters with sex, height, weight, and sexual maturation rating (SMR). Results In total, 620 children were included. Sleep duration was 8.63±0.81 hours in boys and 8.40±0.98 hours in girls. Sleep started from PM 11:00±AM 0:47 in boys and PM 11:13±AM 1:06 in girls, and ended at AM 7:38±AM 0:27 in boys and AM 7:34±AM 0:27 in girls. After adjusting for sex and standardized body mass index, bedtime was delayed as the SMR increased (mean delay for each rating increase, 0.251 hours; P=0.001; 95% confidence interval [CI], 0.105 to 0.397). SMR did not influence the wake-up time, although sleep duration decreased as the SMR increased (mean decrease for each rating increase, 0.258 hours; P=0.001; 95% CI, –0.403 to –0.114). The sleepiness scale scores showed no relationship with SMR. Conclusion Sleep patterns, especially sleep duration and bedtimes, show changes with sexual maturation in adolescents, who are vulnerable to sleep deprivation.

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.

Abstract 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.

Abstract Background Respiratory infections among children, particularly community-acquired pneumonia (CAP), is a major disease with a high frequency among outpatient and inpatient visits. The causes of CAP vary depending on individual susceptibility, the epidemiological characteristics of the community, and the season. We performed this study to establish a nationwide surveillance network system and identify the causative agents for CAP and antibiotic resistance in Korean children with CAP. Methods The monitoring network was composed of 28 secondary and tertiary medical institutions. Upper and lower respiratory samples were assayed using a culture or polymerase chain reaction (PCR) from August 2018 to May 2020. Results A total of 1023 cases were registered in patients with CAP, and PCR of atypical pneumonia pathogens revealed 422 cases of M. pneumoniae (41.3%). Respiratory viruses showed a positivity rate of 65.7% by multiplex PCR test, and human rhinovirus was the most common virus, with 312 cases (30.5%). Two hundred sixty four cases (25.8%) were isolated by culture, including 131 cases of S. aureus (12.8%), 92 cases of S. pneumoniae (9%), and 20 cases of H. influenzae (2%). The cultured, isolated bacteria may be colonized pathogen. The proportion of co-detection was 49.2%. The rate of antibiotic resistance showed similar results as previous reports. Conclusions This study will identify the pathogens that cause respiratory infections and analyze the current status of antibiotic resistance to provide scientific evidence for management policies of domestic respiratory infections. Additionally, in preparation for new epidemics, including COVID-19, monitoring respiratory infections in children and adolescents has become more important, and research on this topic should be continuously conducted in the future.

Abstract Background During puberty, changes in body composition due to sex hormones are associated with lung mechanics. However, little is known about the mediation effect of sex differences in body composition during puberty with total airway resistance. Methods We prospectively recruited 620 children (10–12 years old) from the general population and conducted a cross-sectional study. This study assessed pubertal status according to the five Tanner stages using a questionnaire, line drawings, and each subject’s blood sex hormone profile. Both the impulse oscillation system for total lung mechanics and multifrequency bioelectrical impedance for body composition analyses were conducted. The effects of puberty on body composition and subsequent total lung resistance were evaluated using mediation analysis. Results Among the 503 children enrolled, there were 261 males (51.9%) and 242 females (48.1%). In males, higher testosterone levels corresponded with reduced total lung resistance (β = –0.13, 95% CI = –0.21 to –0.05, p

PurposeThis study aimed to investigate associations of socioeconomic status (SES) with asthma exacerbation and asthma-related hospital utilization factors among children with asthma in the Republic of Korea.MethodsThis study retrospectively analyzed population-level data from the Korean National Health Insurance Service, collected from 2013 through 2019. SES was classified into five categories according to the national health insurance premiums quantiles (0 [lowest] to 4 [highest]). The hazard ratios (HRs) for asthma exacerbation, emergency department (ED) visits, hospital admission, and intensive care unit (ICU) admission were analyzed with respect to SES.ResultsAmong the five SES groups, SES group 0 (medical aid), had the highest tallies and proportions of children who experienced asthma exacerbations (n = 1,682, 4.8%), ED visits (n = 932, 2.6%), hospital admission (n = 2,734, 7.7%) and ICU admission (n = 14, 0.04%). Compared with SES group 4, SES group 0 had adjusted HRs of 3.73 (p = 0.0113) and 1.04 (p

Background An adequate large-scale pediatric cohort based on nationwide administrative data is lacking in Korea. Purpose This study established the National Investigation of Birth Cohort in Korea study 2008 (NICKs-2008) based on data from a nationwide population-based health screening program and data on healthcare utilization for children. Methods The NICKs-2008 study consisted of the Korean National Health Insurance System (NHIS) and the National Health Screening Program for Infants and Children (NHSPIC) databases comprising children born in 2008 (n=469,248) and 2009 (n=448,459) in the Republic of Korea. The NHIS database contains data on age, sex, residential area, income, healthcare utilization (International Classification of Diseases-10 codes, procedure codes, and drug classification codes), and healthcare providers. The NHSPIC consists of 7 screening rounds. These screening sessions comprised physical examination, developmental screening (rounds 2–7), a general health questionnaire, and age-specific anticipatory guidance. Results During the 10-year follow-up, 2,718 children (0.3%) died, including more boys than girls (hazard ratio, 1.145; P

Rhinitis is among the most common respiratory diseases in children. Nonallergic rhinitis, which involves nasal symptoms without evidence of systemic allergic inflammation or infection, is a heterogeneous entity with diverse manifestations and intensities. Nonallergic rhinitis accounts for 16%–89% of the chronic rhinitis cases, affecting 1%–50% (median 10%) of the total pediatric population. The clinical course of nonallergic rhinitis is generally rather mild and less likely to be associated with allergic comorbidities than allergic rhinitis. Here, we aimed to estimate the rate of coexisting comorbidities of nonallergic rhinitis. Nonallergic rhinitis is more prevalent during the first 2 years of life; however, its underestimation for children with atopic tendencies is likely due to low positive rates of specific allergic tests during early childhood. Local allergic rhinitis is a recently noted phenotype with rates similar to those in adults (median, 44%; range, 4%–67%), among patients previously diagnosed with nonallergic rhinitis. Idiopathic rhinitis, a subtype of nonallergic rhinitis, has been poorly studied in children, and its rates are known to be lower than those in adults. The prevalence of nonallergic rhinitis with eosinophilia syndrome is even lower. A correlation between nonallergic rhinitis and pollution has been suggested owing to the recent increase in nonallergic rhinitis rates in highly developing regions such as some Asian countries, but many aspects remain unknown. Conventional treatments include antihistamines, intranasal corticosteroids, and recent treatments include combination of intranasal corticosteroids with azelastin or decongestants. Here we review the prevalence, diagnosis, comorbidities, and treatment recommendations for nonallergic rhinitis versus allergic rhinitis in children.

Abstract Background The purpose was to determine the association between infant exposure to humidifier disinfectant (HD) with neuropsychiatric problems in pre-school children. Methods A total of 2,150 children (age 4–11 months) were enrolled in the Panel Study of Korean Children (PSKC) study. The Korean version of the Child Behavior Checklist (CBCL) was used for assessments of neuropsychiatric problems. 1,113 children who participated in all the first to third PSKC studies and answered a question about HD exposure were finally enrolled. Results There were 717 (64.5%) children in non-HD group who were not exposed to HD and 396 (35.5%) in HD group with former exposure to HD. Exposure to HD was associated with total neuropsychiatric problems (adjusted odds ratio, aOR = 1.54, 95% CI = 1.15–2.06), being emotionally reactive (aOR = 1.55, 95% CI = 1.00–2.39), having attention problems (aOR = 1.96, 95% CI = 1.10–3.47), having oppositional defiant problems (aOR = 1.70, 95% CI = 1.07–2.71), and having attention deficit/hyperactivity problems (aOR = 11.57, 95% CI = 1.03–2.38). The risks for neuropsychiatric problems were clearly increased in boy, firstborn, and secondary smoker. Conclusions Exposure to HD during early childhood had a potential association with subsequent behavioral abnormalities.

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.

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 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.

Abstract Propyl-paraben exposure is associated with aeroallergen sensitization, but its association with atopic dermatitis (AD) is inconclusive. No studies have been conducted on the metabolomic pathways underlying these associations. We investigated the associations between propyl-paraben exposure and aeroallergen sensitization, AD, and Eczema Area and Severity Index (EASI) score and identified the underlying pathways using untargeted metabolomics analysis. We enrolled 455 children in a general population study. Skin prick tests were performed with the assessment of EASI score. Urinary propyl-, butyl-, ethyl-, and methyl-paraben levels were measured. Untargeted metabolomics analysis was performed on the first and fifth urine propyl-paraben quintile groups. The highest urine propyl-paraben quintile group was associated with aeroallergen sensitization, but not with AD. Glycine, threonine, serine, ornithine, isoleucine, arabinofuranose, d-lyxofuranose, citrate, and picolinic acid levels were higher, whereas palmitic acid and 2-palmitoylglycerol levels were lower in the highest quintile propyl-paraben group, than in the lowest quintile group. The propyl-paraben-induced metabolic perturbations were associated with serine and glycine metabolisms, branched-chain amino acid metabolism, and ammonia recycling. Propyl-paraben exposure was associated with aeroallergen sensitization and EASI score, partially via metabolomic changes related with oxidative stress, mTOR, peroxisome proliferator-activated receptors pathway, aryl hydrocarbon receptor signaling pathways, and tricarboxylic acid cycle.

Abstract Lipopolysaccharide (LPS)-binding protein (LBP) is an acute-phase reactant that mediates innate immune responses triggered by LPS. Recent studies indicated a positive correlation of circulating LBP level with chronic low-grade inflammation, a condition present in many non-communicable diseases. We determined the association of serum LBP concentration with allergic sensitization in a general pediatric population. Serum LBP was measured in a sample of children (n = 356; mean age = 9.6 ± 0.2 years) in this population-based cross-sectional study. Skin prick tests (SPTs) were performed to assess allergic sensitization to 22 common inhalant and food allergens. One hundred and seven children (30.1%) were nonsensitized, 160 (44.9%) were monosensitized, and 89 (25.0%) were polysensitized. Children who were mono- or polysensitized had a significantly higher median serum LBP level (25.5 ng/mL, inter-quartile range [IQR] 20.3–30.7) than those who were nonsensitized (20.3 ng/mL, IQR = 14.81–25.8, P

Abstract Background Community–acquired pneumonia (CAP) is one of the leading worldwide causes of childhood morbidity and mortality. Its disease burden varies by age and etiology and is time dependent. We aimed to investigate the annual and seasonal patterns in etiologies of pediatric CAP requiring hospitalization. Methods We conducted a retrospective study in 30,994 children (aged 0–18 years) with CAP between 2010 and 2015 at 23 nationwide hospitals in South Korea. Mycoplasma pneumoniae (MP) pneumonia was clinically classified as macrolide-sensitive MP, macrolide-less effective MP (MLEP), and macrolide-refractory MP (MRMP) based on fever duration after initiation of macrolide treatment, regardless of the results of in vitro macrolide sensitivity tests. Results MP and respiratory syncytial virus (RSV) were the two most commonly identified pathogens of CAP. With the two epidemics of MP pneumonia (2011 and 2015), the rates of clinical MLEP and MRMP pneumonia showed increasing trends of 36.4% of the total MP pneumonia. In children

Background and Objectives: Anaphylaxis, a severe allergic disease, can be triggered by various causes. This study investigated the association between allergic sensitization and anaphylactic symptoms and the severity of anaphylaxis in children.Patients and Methods: A retrospective review of 107 pediatric patients with anaphylaxis was performed between January 1, 2015, and December 31, 2017; 74 patients underwent allergen testing for specific immunoglobulin E. Allergic sensitizations and associations with anaphylactic symptoms and severity were investigated.Results: Overall, 64 (86.5%) patients were sensitized to food or inhalant allergens. In children under 2 years of age, 90.5% were sensitized to food (P = 0.001); in those over 6 years of age, 84.6% were sensitized to inhalant allergens (P = 0.001). Milk sensitization was significantly associated with severe anaphylaxis (P = 0.036). The following symptoms showed significant associations with certain allergen sensitizations: facial edema with food; wheezing with milk; dyspnea with mite, etc. Certain allergen sensitizations presenting as risk factors for anaphylactic symptoms: wheat (adjusted odds ratio [aOR] = 4.644, P = 0.044) and nuts (aOR=3.614, P = 0.041) for wheezing, nuts (aOR=5.201, P = 0.026) for dyspnea, and milk (aOR=4.712, P = 0.048) for vomiting.Conclusion: The allergen sensitization status differed according to the age of the children experiencing anaphylaxis. The severity, symptoms, and signs of anaphylaxis differed depending on the allergen sensitization status.

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.

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.

Background: Solar irradiation affects sensitization to aeroallergens and the prevalence of allergic diseases. Little is known, however, about how the time and amount of solar irradiation during pregnancy affects such risks in children. We aimed to find out how solar irradiation during pregnancy affects sensitization to aero-allergens and the prevalence of allergic diseases in children. Methods: This population-based cross-sectional study involved 7301 aged 6 years and aged 12 years children. Maternal exposure to solar irradiation during pregnancy was evaluated using data from weather stations closest to each child's birthplace. Monthly average solar irradiation during the second and third trimesters was calculated with rank by quartiles. Risks of allergic sensitization and allergic disease were estimated. Results: Relative to the first (lowest) quartile, the adjusted odds ratio (aOR) for allergic sensitization in the fourth (highest) quartile was lowest within solar irradiation during pregnancy months 5–6 (aOR = 0.823, 95% CI 0.720–0.942, p

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.

Abstract The Global Initiative for Asthma (GINA) guidelines do not specify a bronchodilator range for bronchodilator response (BDR) testing and simply recommend a salbutamol dose of 200 to 400 μg. We determined the oscillometric BDR results of children given low-dose (2 puffs, 200 μg) and standard-dose (4 puffs, 400 μg) salbutamol to compare the small airway responses of healthy controls (defined using criteria based on the guidelines developed at the American Thoracic Society) and exclusion subjects (defined as any child that did not meet the inclusion criteria for healthy controls). The oscillometric reactance of small airways is significantly associated with the dose of salbutamol used for BDR testing in exclusion children. We suggest use of the standard-dose of salbutamol for oscillometric BDR testing.

Background/purpose: Activation of cell surface CD30 by immobilized anti-CD30 monoclonal antibodies (mAb) induces strong apoptosis in human eosinophils. This anti-CD30 mAb-induced eosinophil apoptosis is inhibited by the addition of inhibitors of p38, ERK1/2 mitogen-activated protein kinases, and phosphatidylinositol 3-kinase. However, there is little data investigating the role of Bcl-2 and caspases in eosinophil apoptosis induced by anti-CD30 mAb. We sought to determine whether anti-CD30 mAb induces human eosinophil apoptosis via Bcl-2 and caspase pathways. Methods: Peripheral blood was drawn from 37 healthy volunteers. The CD30 expression on eosinophils was measured at various time points. Eosinophils were then cultured in plates precoated with anti-CD30 mAb (clone Ber-H8), isotype control immunoglobulin G1, interleukin (IL)-5, or dexamethasone. Western blot analysis was performed to determine the expression of Bcl-2, procaspase-8, -9, and -3, and caspase-8, -9, and -3 after cross-linking of CD30. Human eosinophils were also cultured in plates precoated with anti-CD30 mAb (clone Ber-H8) in the presence or absence of caspase-9 or -3 inhibitors. Eosinophil apoptosis was assessed using flow cytometry. Results: The addition of anti-CD30 mAb significantly increased eosinophil apoptosis compared with controls. In western blot analysis, the addition of anti-CD30 mAb significantly decreased the expression of Bcl-2 and procaspase-9 and -3 and increased the expression of caspase-9 and -3. The addition of caspase-9 or -3 inhibitors decreased anti-CD30 mAb-induced human eosinophil apoptosis. Procaspase-8 or caspase-8 expression was not changed in response to various stimuli. Conclusion: Anti-CD30 mAb-induced human eosinophil apoptosis is likely to be mediated through Bcl-2 and caspase-9 and -3.

YKL-40, also known as chitinase-3-like protein 1, is an inflammatory glycoprotein that is secreted by various cell types under acute, chronic, and subclinical inflammation conditions. Elevated serum YKL-40 levels are reportedly independently related to diabetes mellitus, coronary artery disease, acute myocardial infarction, and cardiovascular mortality in adults. Therefore, we aimed to investigate the relationship between serum YKL-40 levels, lipid abnormalities, and the atherogenic index of plasma (AIP) in children. We enrolled 479 children aged 10–12 years (mean age: 11.52) in this general population-based, cross-sectional study. All subjects completed questionnaires and were subjected to multifrequency bioelectrical impedance analysis (BIA) to measure their height, weight, and body mass index (BMI). We collected serum samples from all participants to measure YKL-40, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglyceride (TG) levels. Mean serum YKL-40 levels were significantly higher in the low-HDL-C (p=0.017) and high-TG (p=0.010) groups but were not related to TC and LDL-C levels. YKL-40 levels were also higher in the high AIP group (p=0.007). After adjusting for age, gender, and BMI z-score, the associations between serum YKL-40 levels and TG levels (p=0.003), the TG-to-HDL-C ratio (p=0.019), and the AIP value (p=0.012) remained significant. Based on these findings, we suggest that serum YKL-40 may be a useful initial screening tool or follow-up risk indicator for lipid abnormalities, atherosclerosis, and cardiovascular disease in children and adolescents with risk factors, regardless of obesity.

PurposeChest radiography is often performed on patients hospitalized with typical clinical manifestations of bronchiolitis. We aimed to determine the proportion of subjects with pathologic chest radiographic findings and the clinical predictors associated with pathologic chest radiographic findings in young children admitted with the typical presentation of bronchiolitis.MethodsWe obtained the following data at admission: sex, age, neonatal history, past history of hospitalization for respiratory illnesses, heart rate, respiratory rate, the presence of fever, total duration of fever, oxygen saturation, laboratory parameters (i.e., complete blood cell count, high-sensitivity C-reactive protein [hs-CRP], etc.), and chest radiography.ResultsThe study comprised 279 young children. Of these, 26 had a chest radiograph revealing opacity (n=24) or atelectasis (n=2). Multivariate logistic regression analysis showed that after adjustment for confounding factors, the clinical predictors associated with pathologic chest radiographic findings in young children admitted with bronchiolitis were elevated hs-CRP level (>0.3 mg/dL) and past history of hospitalization for respiratory illnesses (all P

PurposeBronchopulmonary dysplasia (BPD) is characterized by inflammation with proteolytic damage to the lung extracellular matrix. The results from previous studies are inconsistent regarding the role of proteinases and antiproteinases in the development of BPD. The aim of the present study was to investigate whether matrix metalloproteinase (MMP)-8, MMP-9, tissue inhibitor of metalloproteinase (TIMP)-2, and TIMP-1 levels in the serum of preterm infants at birth are related to the development of BPD.MethodsSerum was collected from 62 preterm infants at birth and analyzed for MMP-8, MMP-9, TIMP-2, and TIMP-1 by using enzyme-linked immunosorbent assay. MMPs and TIMPs were compared in BPD (n=24) and no BPD groups (n=38). Clinical predictors of BPD (sex, birth weight, gestational age, etc.) were assessed for both groups. The association between predictors and outcome, BPD, was assessed by using multivariate logistic regression.ResultsSex, birth weight, and mean gestational age were similar between the groups. BPD preterm infants had significantly lower TIMP-2 levels at birth compared with no BPD preterm infants (138.1±23.0 ng/mL vs. 171.8±44.1 ng/mL, P=0.027). No significant difference was observed in MMP-8, MMP-9, and TIMP-1 levels between the two groups. Multivariate logistic regression analysis indicated that the TIMP-2 levels were predictive of BPD after adjusting for sex, birth weight, gestational age, proteinuric preeclampsia, and intraventricular hemorrhage (β=-0.063, P=0.041).ConclusionLow TIMP-2 serum levels at birth may be associated with the subsequent development of BPD in preterm infants.

PurposeThe clinical interpretation of children sensitized to allergens is challenging, particularly in children with food allergies. We aimed to examine clinical differences between children with monosensitization and those with polysensitization to common food allergens and to determine risk factors for polysensitization in young children

PurposeWheezing following viral lower respiratory tract infections (LRTIs) in children

Atopic sensitization is a complex phenomenon that changes dynamically with age throughout childhood; its prevalence increases with age in young children. Additionally, with increasing age, the prevalence of sensitization to inhalant allergens and the prevalence of polysensitization to allergens increase. It is also well established that the development of atopic sensitization is the result of a complex interplay of genetic and environmental factors. However, there is considerable heterogeneity in the literature in terms of the effect of different environmental exposures in young children on the subsequent risk of atopic sensitization and allergic diseases. Previous studies on the relationship, in early life, between pet ownership, sex, exposure to secondhand smoke, exposure to traffic-related air pollution components, and atopic sensitization have yielded different results. Recent studies have highlighted the importance of gene-environment interactions, especially during early childhood, on the risk of subsequent atopic sensitization and allergic diseases. Therefore, pediatricians should consider the genetic and environmental determinants of atopic sensitization in infants and young children when diagnosing and treating patients with allergic diseases. Determining ways in which early exposure to these risk factors in young children may be reduced could be beneficial in preventing the likelihood of developing atopic sensitization.

PurposeAllergic disease and its comorbidities significantly influence the quality of life. Although the comorbidities of allergic diseases are well described in adult populations, little is known about them in preschool children. In the present study, we aimed to assess the prevalence and comorbidity of allergic diseases in Korean preschool children.MethodsWe conducted a cross-sectional study comprising 615 Korean children (age, 3 to 6 years). Symptoms of allergic diseases were assessed using the Korean version of the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire that was modified for preschool children. Comorbidities of allergic diseases were assessed by 'In the last 12 months, has your child had symptoms?'.ResultsThe prevalence of symptoms of asthma, allergic rhinitis, and atopic dermatitis as recorded using the ISAAC questionnaire, within the last 12 months was 13.8%, 40.7%, and 20.8%, respectively. The symptom rates of allergic conjunctivitis, food allergy, and drug allergy were 14.8%, 10.4%, and 0.8%, respectively. The prevalence of allergic rhinitis in children with asthma was 64.3% and that of asthma in children with allergic rhinitis was 21.6%. The prevalence of rhinitis in children with conjunctivitis was 64.8% and that of conjunctivitis in children with rhinitis was 23.6%.ConclusionThe prevalence of current rhinitis in our preschool children is shown to be higher than that previously reported. Allergic conjunctivitis is closely associated with asthma and allergic rhinitis. However, further studies are warranted to determine the prevalence and effects of these comorbidities on health outcomes in preschool children.

PurposeAlthough chronic and recurrent rhinosinusitis is prevalent in children, little is known about its causes. Here, we investigated the humoral immunity in children with chronic or recurrent rhinosinusitis.MethodsWe examined 16 children attending the outpatient clinic at the CHA Bundang Medical Center including 11 boys and 5 girls, aged 3.11 years (mean age, 5.6 years), who had rhinosinusitis for >3 months or >3 times per year. The complete blood count with differential and total serum concentrations of Immunoglobulin (Ig) E, IgA, IgD, IgM, IgG, and IgG subclasses (IgG1, IgG2, IgG3, and IgG4) of all children were measured. All subjects received 23-polysaccharide pneumococcal vaccination (PPV), and the levels of antibodies to 5 serologic types (4, 6B, 14, 18C, and 23F) of pneumococcal capsular polysaccharide antigens were measured before and after vaccination. Post-PPV antibody titers ≥0.35 µg/mL or with a ≥4-fold increase were considered as positive responses.ResultsThe titers of IgG, IgA, IgD, and IgM were within normal range in all 16 children, whereas the total IgE concentration was higher than normal in 2 children. IgG1 deficiency was observed in 1 patient and IgG3 deficiency in 3. After PPV, 1 patient failed to respond to all 5 serologic types, 2 failed to respond to 4 serologic types, and 2 failed to respond to 3 serologic types.ConclusionClinicians should consider the evaluation of humoral immune functions in children with chronic or recurrent rhinosinusitis who do not respond to prolonged antibiotic treatment.

BACKGROUND: Bronchodilator responses (BDR) are routinely used in the diagnosis and management of asthma; however, their acceptability and repeatability have not been evaluated using quality control criteria for preschool children.

PurposeThe total number of times a paper is cited, also known as the impact factor (IF) of a medical journal, is widely implied in evaluating the quality of a research paper. We evaluated the citation index data as an IF of Korean J Pediatr in Korean Medical Citation Index (KoMCI) and JCI of Web of Science.MethodsWe calculated the IF of Korean J Pediatr at KoMCI supervised by Korean Association of Medical Journal Editors. And we estimated the IF of Korean J Pediatr by the JCI of Web of Science although it was never officially reported.ResultsThe IF of Korean J Pediatr on KoMCI has increased from 0.100 in the year 2000, to 0.205 in 2008, and 0.326 in 2009. Although the IF of Korean J Pediatr was 0.006 in 2005, 0.018 in 2006, 0.028 in 2008, 0.066 in 2009, and 0.018 in 2010 according to the JCI of Web of Science, the number of citations are steadily increasing.ConclusionUnderstanding and realizing the current status will be a stepping stone for further improvement. The next objective of the Korean J Pediatr is to become registered in the SCI or SCIE. Increasing the IF according to the JCI of Web of Science is crucial in order to achieve this goal.

PurposeThe normal values for lung resistance and lung capacity of children, as determined by impulse oscillometry (IOS), are different for children of different ethnicities. However, reference values there is no available reference value for Korean preschool children have yet to be determined. The aim of the present study was to determine the normal ranges of IOS parameters in Korean preschool children.MethodsA total of 133 healthy Korean preschool children were selected from 639 children (aged 3 to 6 years) who attended kindergarten in Seongnam, Gyeonggi province, Korea. Healthy children were defined according to the European Respiratory Society (ERS) criteria. All subjects underwent lung function tests using IOS. The relationships between IOS value (respiratory resistance (Rrs) and reactance (Xrs) at 5 and 10 Hz and resonance frequency (RF)) and age, height, and weight were analyzed by simple linear and multiple linear regression analyses.ResultsThe IOS success rate was 89.5%, yielding data on 119 children. Linear regression identified height as the best predictor of Rrs and Xrs. Using stepwise multiple linear regressions based on age, height, and weight, we determined regression equations and coefficients of determination (R2) for boys (Rrs5=1.934-0.009×Height, R2=12.1%; Xrs5=0.774+0.006×Height-0.002×Age, R2=20.2% and for girls (Rrs5=2.201-0.012×Height, R2=18.2%; Xrs5=-0.674+0.004×Height, R2=10.5%).ConclusionThis study provides reference values for IOS measurements of normal Korean preschool children. These provide a basis for the diagnosis and monitoring of preschool children with a variety of respiratory diseases.