Korean Adolescent Population Research Articles

Association of the COVID-19 lockdown with health risk behaviors in South Korean adolescents.

Since there is no certainty about when the coronavirus disease 2019 (COVID-19) lockdown will be affected by health risk behaviors, so we investigate the effect of COVID-19-related health risk behavior changes using school-based self-reported data from a nationally representative South Korean adolescent population. We analyzed web-based self-reported data from the Korea Youth Risk Behavior Web-based Survey in 111,878 participants (57,069 in COVID-19 prepandemic); 54,809 in during the COVID-19 pandemic. This study included 12 to 18-year-olds. Self-report questionnaires were used to assess socioeconomic status, health risk behaviors, and psychological factors. Health risk behaviors such as alcohol consumption, substance use, and sexual experience significantly decreased in COVID-19 pandemic than in COVID-19 prepandemic. Psychosomatic changes such as stress levels, violence experience, depression, suicidal ideation, suicidal plans, and suicide attempts were significantly lower in COVID-19 pandemic compared to COVID-19 prepandemic (P < .001). After adjusting for multiple confounding variables, less alcohol consumption (odds ratio [OR] = 0.98; 95% confidence interval [CI] = 0.88-0.93), less exercise (OR = 0.92; 95% CI = 0.89-0.94), less sexual experience (OR = 0.82; 95% CI = 0.77-0.86), less violence experience (OR = 0.61; 95% CI = 0.55-0.67), less stress (OR = 0.86; 95% CI = 0.84-0.88), less depression (OR = 0.85; 95% CI = 0.83-0.88), less suicidal ideation (OR = 0.93; 95% CI = 0.89-0.97), plans (OR = 0.82; 95% CI = 0.76-0.88), attempts (OR = 0.78; 95% CI = 0.71-0.85) were significantly associated with the COVID-19 pandemic compared to COVID-19 prepandemic. The COVID-19 pandemic was associated with changes in health risk behaviors among Korean adolescents, resulting in alcohol drinking, sexual experience, drug use, violence experience, and suicidal behaviors (idea, plan, and attempts) being decreased during the lockdown period.

Network Structure and Clustering Analysis Relating to Individual Symptoms of Problematic Internet Use in a Community Adolescent Population

Introduction: Problematic internet use (PIU) is a psychopathology that includes multiple symptoms and psychological constructs. Because no studies have considered both network structures and clusters among individual symptoms in the context of PIU in a Korean adolescent population, this study aimed to investigate network structures and clustering in relation to PIU symptoms in adolescents. Methods: Overall, 73,238 adolescents were included. PIU severity was assessed using a self-rating scale comprising 20 items and 6 subscales, namely, the Internet Addiction Proneness Scale for Youth-Short Form; KS scale. Network structures and clusters among symptoms were analyzed using a Gaussian graphical model and exploratory graph analysis, respectively. Centrality of strength, closeness, and betweenness scores was also calculated. Results: Our study identified four clusters: disturbance in adaptive functioning, virtual interpersonal relationships, withdrawal, and tolerance. The symptom of confidence served as a node bridging the cluster of virtual interpersonal relationships and other clusters of withdrawal and disturbances of adaptive function. The symptom of craving served as a bridge between the clusters of withdrawal and tolerance with high betweenness centrality. Conclusion: This study identified network structures and clustering among PIU symptoms in adolescents and revealed that positive experiences derived from online interpersonal relationships were an important mechanism underlying PIU. These are novel insights concerning the interconnection among multiple symptoms and related clustering for the mechanism of adolescent PIU in terms of KS-scale PIU assessment.

Association between COVID-19 lockdown and sleep behaviors in Korean adolescents.

To find the effect of coronavirus disease 2019 (COVID-19)-related sleep behavior changes using school-based self-reported data from a nationally representative Korean adolescent population. We analyzed web-based self-reported data from the Korean Youth Risk Behavior Web-based Survey in 98,126 participants (51,651 in 2019 [before the COVID-19 pandemic]; 46,475 in 2020 [during COVID-19 pandemic] 12 through 18 years old were included in this study. Self-report questionnaires were used to assess socioeconomic status, health behaviors, psychological factors, and sleep patterns. During the COVID-19 pandemic, Korean adolescents had a later weekend bedtime (≥1:00 am: 68.2% vs 71.5%, P < .001) and late weekend wake time (≤7:00 am: 13.3% vs 10.7%, P < .001) compared to before COVID-19 pandemic. Average sleep duration (434.7 ± 102.6 vs 428.2 ± 100.4 minutes; P < .001) was significantly lower during the COVID-19 pandemic and weekend catch-up sleep >2 hours (42.1% vs 43.7%; P < .001), late chronotype (17.1% vs 22.9%, P < .001) were significantly higher during COVID-19 pandemic. After adjusting for multiple confounding variables, short sleep duration (≦5 hours, odds ratio [OR] 1.14; 95% confidence interval [CI] 1.10-1.19), 6 hours, OR 1.07; 95% CI 1.03-1.12), long weekend catch-up sleep (OR, 1.08; 95% CI, 1.06-1.11) and late chronotype (OR, 1.43; 95% CI, 1.38-1.47) were significantly associated with COVID-19 pandemic. The COVID-19 pandemic was associated with changes in sleep behavior among Korean adolescents, resulting in later bed and wake-up times, increased weekend catch-up sleep, and a shift of chronotype toward eveningness.

Socioeconomic Disparities in Adolescents' Caries Prevalence

Introduction: Policymakers and academics have explored the behavioral approach in their attempts to explain and address the socioeconomic disparities in adolescents' oral health. However, evidence regarding this issue is scarce in the Korean adolescent population. This study aimed to examine whether socioeconomic status is associated with dental caries and whether oral health-related behaviors (OHRBs) explain or moderate the hypothesized association in Korean adolescents. Methods: A secondary analysis was conducted using the Korea National Health and Nutrition Examination Survey data from 2016 to 2019. Adolescents (n = 1062) aged 13–18 years were included in the analysis. The association between income and untreated decayed permanent teeth (DT) was investigated, focusing on the intermediary roles of OHRBs, using hierarchical negative binomial regression models. Results: Higher income (incidence rate ratio [IRR] 0.70, P &lt; 0.001), regular breakfast intake (IRR 0.64, P &lt; 0.001), higher fruit and vegetable consumption (IRR 0.93, P &lt; 0.001), preventive dental check-ups (IRR 0.84, P &lt; 0.001), and frequent toothbrushing (IRR 0.73, P &lt; 0.001) were associated with lower DT. The income-DT association remained significant and its magnitude was only slightly attenuated, after adjusting for OHRBs (IRR 0.74, P &lt; 0.001). Significant interaction effects were found between income and each OHRB on DT (all with P &lt; 0.001), and interaction patterns differed by behavior type: The income-DT association was stronger in the presence of unfavorable dietary-and favorable dental care-behaviors. Conclusion: The study findings suggested that adolescent oral health equity interventions should prioritize the structural approach and give more thorough consideration to the interactions between socioeconomic and behavioral factors.

Relationship between subjective sleep quality and periodontal disease-related symptom in the Korean adolescent population

Relationship between subjective sleep quality and periodontal disease-related symptom in the Korean adolescent population

Energy-drink consumption is associated with asthma, allergic rhinitis, and atopic dermatitis in Korean adolescents

Few studies have evaluated the effects of energy drinks on allergic diseases. The purpose of this investigation was to evaluate the association between energy drinks and various allergic diseases, including asthma, allergic rhinitis, and atopic dermatitis, in a large representative Korean adolescent population. This cross-sectional study used data from the Korea Youth Risk Behavior Web-based Survey collected from 2015 to 2016. A total of 129,809 participants (n = 67,056 for males; n = 62,753 for females) aged 12-18 years were included and were asked about their frequency of consumption of energy drinks such as Hot6®, Redbull®, and Bacchus®. Their history of asthma, allergic rhinitis, and atopic dermatitis throughout life and in the last 12 months were obtained. The association between the frequency of energy-drink consumption and allergic diseases was analyzed using multiple logistic regression with adjustment for various covariates. Age, sex, physical activity, obesity, region of residence, economic level, paternal and maternal educational level, smoking, and alcohol consumption differed significantly according to the frequency of energy-drink consumption (each P < 0.001). Frequent energy-drink consumption (≥7 times a week) was significantly associated with asthma throughout life (odds ratio [OR] = 1.30, 95% confidence interval (CI) = 1.03-1.64, P = 0.025), asthma within the last 12 months (OR = 1.65, 95% CI = 1.16-2.35, P = 0.006), allergic rhinitis within the last 12 months (OR = 1.21, 95% CI = 1.02-1.44, P = 0.030), and atopic dermatitis within the last 12 months (OR = 1.49, 95% CI = 1.17-1.90, P = 0.001) compared to no energy-drink consumption in the full-adjusted model. Frequent energy-drink consumption is associated with allergic diseases, including asthma, allergic rhinitis, and atopic dermatitis, in Korean adolescents.

Relationship between Insufficient Sleep and Bad Breath in Korean Adolescent Population.

This cross-sectional study sought to evaluate the association between insufficient sleep and bad breath among Korean adolescent population. It was based on the 13th Korea Youth Risk Behavior Web-Based Survey (2017). From 64,991 participants (aged 13–18 years), the final participation rate in the survey was 95.8% (62,276 participants; 31,624 boys and 30,652 girls). A complex sample logistic regression was performed to identify the relationship between insufficient sleep and halitosis, after adjusting for all covariates. In Model II for estimating the adjusted odds ratio (AOR) for general characteristics, students who answered “not at all sufficient”, indicating insufficient sleep, were at higher risk of bad breath than those who answered “completely sufficient” (AOR = 2.09, 95% confidence interval, CI = 1.91–2.30). In Model III, for estimating the AOR adjusted for all covariates, students who answered “not at all sufficient”, indicating insufficient sleep, were at higher risk of bad breath than those who answered “completely sufficient” (AOR = 1.47, 95% CI = 1.33–1.83). It is necessary for families and schools to have health education lessons that recognize insufficient sleep among adolescents may be a cause of bad breath and therefore optimal sleeping habits and oral health behaviors should be promoted.

Gene expression profiling in the hippocampus of adolescent rats after chronic alcohol administration.

In South Korea, the average age of onset of alcohol drinking is 13.3years and half of adolescents drink alcohol more than once a month; 8.45% of the Korean adolescent population become future high-risk alcohol drinkers. Chronic alcohol abuse causes physical and psychiatric health problems such as alcohol addiction, liver disease, stroke and cognitive impairments. This study aimed to investigate the effect of alcohol on gene expression and their function in the hippocampus of adolescent rats. After chronic alcohol administration in male (control, n=6; alcohol, n=6) Sprague-Dawley rats for 6weeks, we analysed up- or down-regulated genes using RNA-sequencing technology. We found 83 genes more than 1.5-fold up- or down-regulated in the alcohol-treated group. Among them, genes (Dnai1, Cfap206 and Dnah1) associated with cilium movement were up-regulated in the alcohol-treated group. Mlf1, related to cell cycle arrest, was also up-regulated in the alcohol-treated group. On the other hand, genes (Smad3 and Plk5) involved in negative regulation of cell proliferation were down-regulated in the hippocampus by chronic alcohol administration. In addition, expression levels of genes associated with oxidative stress (Krt8 and Car3) and migration (Vim) were changed by chronic alcohol administration. These results pave a path for a better understanding of the neuromolecular mechanisms mediated by chronic alcohol exposure in the hippocampus of adolescents and negative pathology due to chronic alcohol abuse.

SUN-134 The Frequency of Type 1 Diabetes among Adolescent Patients with Moyamoya Disease

Background: Moyamoya disease is a rare cerebrovascular condition characterized by stenosis or occlusion of the anterior circulation vessels of the brain, with development of the collateral vessels. The pathogenesis of moyamoya is not well known. The role of immunology as well as the role of genetics has been suggested, and recent reports have noted an association between moyamoya and type 1 diabetes mellitus (T1DM). In this study, we evaluated the frequency of T1DM in children and adolescents with moyamoya disease. Methods: All children and adolescents who were confirmed moyamoya disease by magnetic resonance angiography (MRA) before the age of 20 years in Severance Hospital were included. Retrospectively chart review was conducted and we evaluated the frequency of endocrine autoimmune disease among patients with moyamoya disease. In addition, the clinical characteristics of patients with both of T1DM and moyamoya disease are described. Results: Seven hundreds and two patients (current mean age, 14.7 ± 4.8 years) were included. They were diagnosed moyamoya disease at an average age of 9.0 years. Female patients were 57.3%. Five of them (0.71%, mean age 13.3 years, one male) were noted T1DM. This prevalence was significantly higher than that in general Korean adolescent (0.081%). The incidence of T1DM in Moyamoya disease was 125 per 100,000 per year and this was also significantly higher than that in general Korean adolescent population (3.19 per 100,000 per year). One of them had been diagnosed both of T1DM and Grave’s disease. Two patients with T1DM were diagnosed with moyamoya disease earlier than T1DM, and at the time of diagnosis with diabetes, their C-peptide levels were not definitely low. However, their C-peptide levels decreased gradually in a short period of time and they also had GAD antibody. All patients had Moyamoya disease, bilaterally. Conclusion: In the present study, not a few patients have both of moyamoya disease and T1DM. This supports a possible autoimmune component to the pathogenesis of moyamoya disease. Because stroke-like symptoms in moyamoya syndrome are similar to hypoglycemic symptoms, we recommend that clinicians consider the T1DM when evaluating patients with moyamoya disease.

1.47 Association Between Smartphone Use and Mental Health in Adolescents: National Cross-Sectional Study

Smartphones are adopted as a universal tool for information, communication, education, and entertainment, especially among adolescents. We aimed to investigate the association of smartphone use with depressive symptoms and suicidal behaviors in a large, representative Korean adolescent population.

The Effects of Parental Management of Peer Relationships on Male and Female Adolescents’ Social Skills, Friendship Qualities, Loneliness, and Delinquency

This study purported to examine relationships between parental peer management and adolescents' social skills, friendship quality, loneliness, and delinquency and further shed light on gender differences in these relationships. Four-hundred-seventy adolescents living in Seoul, Gyunggi, and Incheon areas (240 males and 230 females) completed pencil-and-paper assessments of parental management of adolescent peer relationships, adolescent social skills, adolescent friendship quality, adolescent loneliness, and adolescent delinquency. Given the lack of research validating the Parental Management of Peer relationship Inventory (PMPI; Mounts, 2001) using a Korean adolescent population and the possibility of cross-cultural differences in the structure of the parental peer management behaviors, exploratory factor analyses were conducted for the original PMPI items and developed the four scales (Consulting on Peer Relationships, Insisting/Prohibiting Certain Friendships, Emphasizing Healthy Friendships, and Autonomy Granting in Peer Relationships). Correlation and hierarchical multiple regression analyses suggest that parental consulting, autonomy granting, and emphasizing healthy friendships are positive parental peer management dimensions, with positive effects on adolescent social outcomes and negative or no effects on adolescent loneliness and delinquency. On the other hand, parental insisting/prohibiting was found to contribute to adolescents' feeling lonely and engaging in delinquent behaviors and have no effects on other adolescent outcomes. Gender differences were found in some relationships involving parental consulting and autonomy granting. Clinical implications of these findings were discussed.

The associations between internet use time and school performance among Korean adolescents differ according to the purpose of internet use.

Although overuse of the internet has been suggested to be related to poor academic performance, the effects of internet use for education on academic performance showed conflict results in previous studies. Accordingly, the associations of school performance with internet use for study and for general purpose were explored in a large population of Korean adolescents. Cross-sectional data from the 2013 Korean Youth Risk Behaviour Web-based Survey (KYRBWS) were retrieved for 59,105 12- to 18-year-old adolescents. The associations between school performance and internet use were analysed using multinomial logistic regression with complex sampling. Days of physical activity, sex, obesity, region of residence, income level, parental education level, stress, sleep time, smoking, alcohol consumption, drug use, and total study time were recorded and adjusted for as confounders. Higher school performance was positively associated with longer internet use for study (adjusted odds ratio, AOR, of 2+ h [95% confidence interval] = 2.43 [2.10–2.82], 2.02 [1.78–2.30], 1.66 [1.46–1.89], and 1.30 [1.15–1.47] for performance groups A, B, C, and D, respectively, P < 0.001) but negatively associated with longer internet use for general purpose (AOR of 3+ h [95% confidence interval] = 0.68 [0.60–0.78], 0.85 [0.76–0.94], 0.83 [0.75–0.92], and 0.98 [0.89–1.08] for performance groups A, B, C, and D, respectively, P < 0.001). Higher school performance significantly positively correlated with internet use for study but negatively correlated with internet use for general purpose. Academic use of the internet could be a means of achieving good school performance.

Allergic rhinitis, atopic dermatitis, and asthma are associated with differences in school performance among Korean adolescents.

Several studies have reported negative relations between allergic diseases and school performance but have not simultaneously considered various allergic diseases, including allergic rhinitis, asthma, and atopic dermatitis, and only examined a limited number of participants. The present study investigated the associations of allergic rhinitis, asthma, and atopic dermatitis with school performance in a large, representative Korean adolescent population. A total of 299,695 7th through 12th grade students participated in the Korea Youth Risk Behaviour Web-based Survey (KYRBWS) from 2009 to 2013. The subjects’ history of allergic rhinitis, asthma, and atopic dermatitis and number of school absences due to these diseases in the previous 12 months were examined and compared. School performance was classified into 5 levels. The relations between allergic disorders and school performance were analyzed using multiple logistic regressions with complex sampling and adjusted for the subjects’ durations of sleep, days of physical activity, body mass indexes (BMIs), regions of residence, economic levels, parents’ education levels, stress levels, smoking status, and alcohol use. A subgroup analysis of the economic groups was performed. Allergic rhinitis was positively correlated with better school performance in a dose-dependent manner (adjusted odds ratios, AOR, [95% confidence interval, CI] = 1.50 [1.43–1.56 > 1.33 [1.28–1.38] > 1.17 [1.13–1.22] > 1.09 [1.05–1.14] for grades A > B > C > D; P < 0.001). Asthma was negatively correlated with better school performance (AOR [95% CI] = 0.74 [0.66–0.83], 0.87 [0.79–0.96], 0.83 [0.75–0.91], 0.93 [0.85–1.02] for performance A, B, C, and D, respectively; P < 0.001). Atopic dermatitis was not significantly correlated with school performance. The subgroup analysis of the students’ economic levels revealed associations between allergic diseases and school performance. Compared to other allergic disorders, the asthma group had more school absences due to their symptoms (P < 0.001). School performance was positively correlated with allergic rhinitis and negatively correlated with asthma in Korean adolescents, even after adjusting for other variables. The asthma group had an increased number of school absence days, which presumably contributes to these students’ poor school performance.

Inverse relationship between sleep duration and myopia.

To investigate the association between sleep duration and myopia. This population-based, cross-sectional study using a nationwide, systemic, stratified, multistage, clustered sampling method included a total of 3625 subjects aged 12-19 years who participated in the Korean National Health and Nutrition Examination Survey 2008-2012. All participants underwent ophthalmic examination and a standardized interview including average sleep duration (hr/day), education, physical activity and economic status (annual household income). Refractive error was measured by autorefraction without cycloplegia. Myopia and high myopia were defined as ≤-0.50 dioptres (D) and ≤-6.0 D, respectively. Sleep durations were classified into 5 categories: <5, 6, 7, 8 and >9 hr. The overall prevalence of myopia and high myopia were 77.8% and 9.4%, respectively, and the overall sleep duration was 7.1 hr/day. The refractive error increased by 0.10 D per 1 hr increase in sleep after adjusting for potential confounders including sex, age, height, education level, economic status and physical activity. The adjusted odds ratio (OR) for refractive error was 0.90 (95% confidence interval [CI], 0.83-0.97) per 1 hr increase in sleep. The adjusted OR for myopia was decreased in those with >9 hr of sleep (OR, 0.59; 95% CI, 0.38-0.93; p for trend = 0.006) than in those with <5 hr of sleep. However, high myopia was not associated with sleep duration. This study provides the population-based, epidemiologic evidence for an inverse relationship between sleep duration and myopia in a representative population of Korean adolescents.

Cohort Profile: The JS High School study (JSHS): a cohort study of Korean adolescents

Major aetiologies of atherosclerotic cardiovascular diseases begin in childhood and atherosclerotic vascular abnormalities can be observed among children and adolescents. Adolescent cohort studies have important advantages because they can observe earlier changes in vascular structure and function. The purpose of the JS High School study (JSHS) is to identify biomarkers predicting or indicating early structural and functional vascular change in adolescents. The JSHS is a prospective cohort study of a Korean adolescent population. The target population of the JSHS was first-graders (aged 14 to17 years) at a high school of South Korea. Enrolment and baseline examinations were conducted in years 2007, 2010, 2011 and 2012. Among the total eligible population of 1115 students, 1071 (96.1%) participated in the study and completed all baseline examinations. Informed consent forms were obtained from each participant and his/her parent or guardian. Baseline examinations include: questionnaires on demographics, health behaviours, medical history, and depression symptoms; fasting blood analysis; anthropometric measurement; body impedance analysis; blood pressure measurement; radial artery tonometry; bone densitometry; pulmonary function tests; and carotid ultrasonography. Participants enrolled from 2007 through 2012 were re-examined after 30 months of follow-up, and those who enrolled in 2012 were re-examined after 24 months of follow-up. The corresponding author may be contacted for potential collaboration and data access.

Three clustering patterns among metabolic syndrome risk factors and their associations with dietary factors in Korean adolescents: based on the Korea National Health and Nutrition Examination Survey of 2007-2010.

BACKGROUND/OBJECTIVEEven though the prevalence of metabolic syndrome in adolescents is increasing, little is presently known about this syndrome in adolescents. This study aimed to cluster metabolic risk factors as well as examine the associations between identified patterns and nutrient intake using data from the Korean National Health Examination and Nutritional Assessment (KNHANES).SUBJECTS/METHODSA total of 2,958 subjects aged 10 to 18 years along with both biochemical and dietary data information were obtained from KNHANES 2007-2010. Six components of metabolic syndrome were used to identify any patterns via factor analysis. Individuals were categorized into quartile groups according to their pattern score.RESULTSThree clustering patterns with high loadings were identified and named as follows: 1) high blood pressure, 2) dyslipidemia, and 3) glucose abnormality patterns. The high blood pressure pattern showed high loadings of systolic and diastolic blood pressures, the dyslipidemia pattern showed high loadings of triglyceride and HDL-cholesterol levels, and the glucose abnormality pattern showed high loadings of fasting blood glucose levels. Intakes of fat and riboflavin were significantly decreased, whereas those of sodium and niacin were significantly increased across the quartiles in the dyslipidemia pattern. No nutrient intake except that of thiamin was significantly associated with the high blood pressure or glucose abnormality pattern.CONCLUSIONOur findings show that metabolic syndrome risk factors in the Korean adolescent population are characterized by three distinct patterns, which are differentially associated with dietary factors. Characterizing metabolic risk factors and providing specific dietary guidelines for target groups are important.

Low level of immunity against hepatitis A among Korean adolescents: Vaccination rate and related factors

We evaluated the current vaccination rate and immunity in the Korean adolescent population and analyzed their parents' attitudes toward hepatitis A virus (HAV) vaccination. Between March and April 2011, sera were collected for immunoglobulin (Ig) G anti-HAV testing from students in their first year of high school from 12 different high schools located in southwestern Seoul. Simultaneously, questionnaires were given to the parents of the students to evaluate factors related to HAV vaccination, including demographics, HAV vaccination status, reason for getting the vaccination, and awareness regarding HAV. Sera from 2,879 subjects and questionnaires from their parents were collected. The HAV vaccination rate among adolescents aged between 14 and 17 years was 18.9%, and the seroprevalence was 15.4%. Among subjects who reported receiving the HAV vaccination, the IgG anti-HAV seropositivity rate was only 42.2%. For subjects who were not vaccinated, the IgG anti-HAV seropositivity rate was 9.1%. The most significant reason for receiving the vaccination was recommendation from health care providers; the most important source of information regarding the vaccination was public health organizations. HAV vaccination rate and anti-HAV seroprevalence in Korean adolescents was low; the seropositivity rate in the vaccinated group was lower than expected. Actively recommending HAV vaccination in this group is required, and routine, nationwide, government-sponsored vaccination of adolescents against HAV should be considered.

Prevalence of the metabolic syndrome and abnormal lipid levels among Korean adolescents

Early identification of the metabolic syndrome (MS) and abnormal lipid levels with subsequent life-style intervention is vital to halt disease progression and safeguard the future health of children and adolescents. Data from a representative sample of 1554 adolescents (821 boys and 733 girls) aged 10-19 from the 2007-2008 Korea National Health and Nutrition Examination Survey was analysed. The MS was defined using the paediatric criteria of the International Diabetes Federation. Abnormal lipid levels were classified according to the guidelines of the American Academy of Pediatrics. Approximately 13.7% of adolescents have a body mass index (BMI) between the 85th and 94th percentiles, and 8.4% have a BMI of ≥95th percentile. The prevalence of the MS was 2.3% among all the participants, 2.7% among boys and 2.1% among girls. The prevalence of the MS was 2.8% among overweight adolescents and 23.7% among obese adolescents. A low high-density lipoprotein cholesterol level was the most common component for the MS. Nearly 20% of adolescents (21% of boys and 19% of girls) had at least one lipid abnormality. Approximately 32% of overweight adolescents and 50% of obese adolescents were candidates for therapeutic life-style counselling based on lipid levels. The present study provides the most updated prevalence estimates of the MS in the Korean adolescent population and highlights the strong association of the MS with BMI. The prevalence of abnormal lipid levels in overweight and obese adolescents is high, illustrating the large burden of cardiovascular disease in the future Korean population.

Aminotransferase Upper Reference Limits and the Prevalence of Elevated Aminotransferases in the Korean Adolescent Population

For the pediatric population, upper reference limits (URLs) for aminotransferase levels have not been established. The prevalence of high aminotransferase levels provides important information regarding the burden of liver disease in the current childhood obesity endemic. We set the URL of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) for participants ages 10 to 19 years (n = 2746) from the 2007 to 2009 Korea National Health and Nutrition Examination Survey at the 97.5th percentile of that population who were determined to be at low risk for liver disease (n = 1717; low risk was defined as testing negative for hepatitis B virus surface antigens, the absence of alcohol use disorder, having normal body mass index, and having normal lipid or carbohydrate metabolism). The URLs for ALT were 33 IU/L for boys and 25 IU/L for girls, and the corresponding limits for AST were 33 IU/L for boys and 28 IU/L for girls. The weighted prevalence of elevated ALT levels was 6.5% in the sample, 8.2% in boys and 4.5% in girls. The prevalence of elevated AST levels was 3.9% and had no sex differences. We also found that elevated ALT levels are associated with male sex, older age, obesity, and presence of abnormal lipid levels. Having elevated AST levels is associated with obesity, younger age, and exhibiting laboratory indicators of abnormal lipid metabolism. Aminotransferase URLs are being established for the first time, and our results may be useful in determining a baseline level for monitoring the secular trends of liver disease in future studies of adolescent populations.

Association Between Short Sleep Duration and Obesity Among South Korean Adolescents

Short sleep duration and obesity are common health concerns in youth. This study of South Korean adolescents explores the association between the two conditions analyzing secondary data from the 2007 Korea Youth Risk Behavior Web-Based Survey. The sample is representative of the South Korean adolescent population (N = 73,836). For data analysis, analysis of variance, chi-square test, and logistic regression were used. Findings indicated that (a) sleep duration is inversely associated with levels of body mass index, F(4, 72654) = 240.07, p < .0001, and risks for overweight and obesity, χ(2)(4, 72659) = 27.41, p < .0001; and (b) after controlling for obesity-related factors, reduced sleep is strongly associated with a greater risk for overweight and obesity, OR = 0.94, p < .0001. Given the important link between sleep and obesity, health professionals should consider sleep habits as a significant factor in obesity-related problems of youth.