Hand and Oral Hygiene Practices of South Korean Adolescents Before and During the COVID-19 Pandemic

Trends in adolescent violence victimization pre-, intra-, and post-COVID-19 pandemic in South Korea, 2012-2023: a nationwide cross-sectional study

BACKGROUND

Adolescent violence victimization is a major public health concern, but research has been limited by short durations and small samples, restricting long-term understanding. This study examined its trends and vulnerabilities in South Korea, focusing on the impact of COVID-19 pandemic.

METHODS

Data were collected from 740,687 nationally representative samples (7-12th grade adolescents) through the Korean Youth Risk Behavior Web-based Survey from 2012 to 2023. Violence victimization was defined as treatment at a hospital in the past 12 months due to physical, mental, or property victimization. To assess the impact of the COVID-19 pandemic, the data were categorized into pre-(2012-2019), intra-(2020-2022), and post-(2023) pandemic periods, and analyzed using weighted regression models.

RESULTS

A total of 740,687 participants (379,021 boys [51.17 %]) were included in this analysis from 2012 to 2023. The overall prevalence of adolescent violence victimization significantly declined from 2.91 % [95 % CI, 2.77-3.04] to 1.94 % [1.86-2.02] in pre-pandemic, then decreased to 1.13 % [1.03-1.24] during the early intra-pandemic, before rising to 2.29 % [2.12-2.46] in the post-pandemic. Vulnerable subgroups included students in 7-9th grades, those with depressive symptoms, attendees of all-boys schools, residents of facilities, current substance users, all exhibiting greater susceptibility to violence victimization.

CONCLUSION

This study identified a U-shaped trend in adolescent violence victimization in South Korea throughout the pandemic. Relative risk was associated with school and living environments, psychosocial factors, and substance use. Findings highlight the need for a systemic approach to interventions, addressing both individual vulnerabilities and structural factors to strengthen prevention.

National trends in dyslipidemia prevalence, awareness, treatment, and control in South Korea from 2005 to 2022

Dyslipidemia has steadily increased in South Korea over the past two decades, emerging as a major public health concern and key risk factor for cardiovascular disease. Thus, our study aimed to investigate long-term trends in the prevalence, awareness, treatment, and control of dyslipidemia in South Korea, including the COVID-19 pandemic. This study utilized data from nationally representative cross-sectional surveys conducted as part of the Korea National Health and Nutrition Examination Survey from 2005 to 2022, analyzing long-term trends of dyslipidemia among 98,396 individuals aged over 30. Weighted linear and binary logistic regression were performed to calculate the β coefficients, βdiff, and weighted odds ratios with 95% confidence intervals (CIs). Weighted odds ratios were computed for various socioeconomic groups using aggregated data from 2005 to 2022. The prevalence of dyslipidemia increased from 41.30% (95% CI 40.40-42.21) in 2005-2009 to 48.41% (47.36-49.47) in 2020-2022. Awareness increased from 17.87% (16.75-18.99) to 48.90% (47.34-50.47), treatment from 7.10% (6.39-7.80) to 38.19% (36.61-39.76), and control among prevalence from 6.49% (5.79-7.19) to 31.82% (30.33-33.32). Treatment (βdiff, 3.94 [1.97-5.92]) and control among prevalence (βdiff, 3.52 [1.67-5.38]) increased more rapidly during the pandemic. Higher odds of dyslipidemia were associated with male sex, older population, rural residence, high BMI, central adiposity, low education and income levels, smoking, and high-risk alcohol consumption. Lower odds of awareness, treatment, and control among individuals with dyslipidemia were associated with male sex, younger population, rural residence, higher education and income levels, smoking, and high-risk alcohol consumption. Over the past 18 years, the prevalence, awareness, treatment, and control of dyslipidemia have steadily increased, with persistent disparities among socioeconomic groups.

Nationwide Trends in Screen Time and Associated Risk Factors by Family Structures Among Adolescents, 2008-2022: Nationwide Cross-Sectional Study

BACKGROUND

Although understanding long-term trends in adolescent screen time and the influence of family structure is essential, there is a lack of research addressing these issues comprehensively.

OBJECTIVE

This study aimed to conduct comprehensive investigations into adolescent screen time before and during the COVID-19 pandemic, with a particular focus on family structures.

METHODS

This study used nationwide, large-scale data from the Korea Youth Risk Behavior Web-Based Survey from South Korea. We aimed to indicate the changes in adolescent screen time over 15 years from 2008 to 2022. Weighted linear regression was used to analyze annual trends in screen time before and during the pandemic, and stratified analyses were conducted to examine associated risk factors across different family structures.

RESULTS

This study used data from a total of 836,972 individuals (n=403,456, 48.2% women), with an age range of 12-18 years. The analysis revealed an overall increase in screen time prepandemic (β=8.06, 95% CI 7.74-8.39), with a notable increase observed at the onset of the pandemic (β=162.06, 95% CI 159.49-164.64). Among diverse family structures, the orphanage group showed the most substantial increase in screen time during the pandemic (βdiff=221.90, 95% CI 159.62-284.17). Risk factors associated with screen time during the pandemic varied by family structure. Notably, the nuclear family group presented distinct screen time-related risk factors, including grade, region of residence, physical activity frequency, sadness and despair, and the highest education level of parents.

CONCLUSIONS

There has been a notable increase in average screen time among adolescents since the onset of the pandemic, with the orphanage group exhibiting a pronounced trend. The risk factors associated with screen time during the pandemic varied for each family structure. Findings from this study suggest that the implementation of individualized measures tailored to each family structure should be adopted to effectively address the increased issue of adolescent screen time since the pandemic.

Association between behavioral and sociodemographic factors and high subjective health among adolescents: a nationwide representative study in South Korea

The need to understand subjective health has increased during the COVID-19 pandemic, given its substantial impact on lifestyle habits and perceptions. Thus, this study aimed to investigate the trends and association of subjective health with demographic and behavioral factors, primarily focusing on the change when the COVID-19 pandemic emerged. This study used data from the Korea Youth Risk Behavior Web-based Survey, comprising 1,190,468 adolescents aged 12-18 years (female, 48.49%). We investigated the trends and association of subjective health with demographic and behavioral factors from 2006 to 2023. A weighted linear regression and joinpoint regression were conducted to evaluate the trend in adolescent subjective health, while logistic regression was used to assess associated factors. A stratification analysis was performed for subgroups to determine variations across different demographic and behavioral groups. The prevalence of reporting high subjective health increased throughout the years before the COVID-19 pandemic; however, subjective health exhibited a decreasing trend during the pandemic. Regarding demographic factors, female sex (ratio of odds ratio [ROR], 0.85 [95% CI, 0.83-0.87]), low-income households (ROR, 0.67 [95% CI, 0.64-0.69]), and low academic achievement (ROR, 0.83 [95% CI, 0.81-0.85]) were associated with less likelihood of reporting high subjective health. Healthier behavioral factors (ROR, breakfast consumption, 1.13 [95% CI, 1.10-1.16]; sufficient fruit intake, 1.12 [95% CI, 1.09-1.15]; sufficient physical activity, 2.02 [95% CI, 1.95-2.09]) were associated with higher subjective health, and the disparities increased during the COVID-19 pandemic. To address the observed decline in subjective health among adolescents during the COVID-19 pandemic, targeted interventions aimed at promoting healthy behaviors among particularly vulnerable demographics are crucial.

Nationwide trends in sadness, suicidal ideation, and suicide attempts among multicultural and monocultural adolescents in South Korea during the COVID-19 pandemic, 2011-2022

BACKGROUND

Researches on the mental health of Korean adolescents during COVID-19 have largely focused on those from monocultural families, but there is limited data on sadness, suicidal ideation, and suicide attempts in multicultural adolescents.

METHODS

This nationwide serial cross-sectional study included 688,708 adolescents aged 12-18 years who participated in the Korean Youth Risk Behavior Web-based Survey from 2011 to 2022. We compared and analyzed the prevalence of sadness, suicidal ideation, and suicide attempts among multicultural and monocultural adolescents. Multicultural adolescents were defined as those with at least one non-Korean parent.

RESULTS

In 2021, the prevalence of sadness among multicultural adolescents was 31.86% [95% confidence interval (CI) 30.00-33.71], suicidal ideation 17.17% (15.74-18.61), and suicide attempts 4.25% (3.51-4.99). Among monocultural adolescents, the prevalence rates were 26.09% (25.50-26.69) for sadness, 12.41% (11.97-12.85) for suicidal ideation, and 1.92% (1.76-2.67) for suicide attempts. Adolescents from multicultural backgrounds were found to have higher rates of sadness, suicidal ideation, and suicide attempts. In the general population, these rates had decreased during the pre-pandemic period but increased after the onset of the pandemic then stabilized from 2020 to 2021. Female gender, smoking, alcohol use, and low school performance emerged as significant risk factors. However, no distinct risk factors specifically linked to suicide attempts were identified. Joinpoint regression analysis results aligned with the beta slope values in the main findings, reflecting a consistent pattern across both analyses.

CONCLUSIONS

This study revealed that sadness, suicidal ideation, and suicide attempts increased during the pandemic, reversing a pre-pandemic decline. Multicultural adolescents faced these issues more than monocultural ones, underlining the need for targeted public health measures to support at-risk adolescents during pandemics.

Associations between weight-control methods and depression among Korean adolescents: a study based on a national dataset

BACKGROUND/OBJECTIVES

The increasing prevalence of overweight and obesity has become a significant global burden, with more than 40% of the global adult population attempting to lose weight. Previous studies on the impact of weight-control methods on mental health, especially among adolescents, are limited. Thus, this study aimed to investigate the association between various weight-control methods and depression among adolescents, with the goal of informing healthier weight management decisions and promoting effective methods.

SUBJECTS/METHODS

This nationwide study utilized data from the Korea Youth Risk Behavior Web-based Survey, including a sample of 418,254 adolescents collected over 12 yrs (2007-2019). We conducted a weighted complex sample analysis to compare depression rates associated with specific weight-control methods, including exercise, fasting (≥ 24 h), eating less, taking prescription/non-prescription weight-loss medication, taking laxatives or diuretics, vomiting, one-food diet, taking oriental medicine, and diet foods.

RESULTS

Of the 418,254 participants, 45.96% (192,246) were male. Among male participants, fasting (≥ 24 h; weighted odds ratio [wOR], 1.43; 95% confidence interval [CI], 1.36-1.51) and vomiting (wOR, 1.49; 95% CI, 1.35-1.66) were associated with an increased risk of depression. Among female participants, prescribed (wOR, 0.82; 95% CI, 0.74-0.90) and non-prescribed (wOR, 0.89; 95% CI, 0.82-0.97) weight-loss medication reduced the risk of depression. However, fasting (≥ 24 h; wOR, 1.47; 95% CI, 1.41-1.52) and vomiting (wOR, 1.45; 95% CI, 1.36-1.55) significantly increased the risk of depression.

CONCLUSION

The risk of depression varies depending on the weight-control method, with a consistent trend observed across both sexes. Methods such as vomiting, fasting, taking oriental medicine for weight loss, and consuming diet foods increased the risk of depression, while weight-loss medications were associated with reduced depression symptoms in females. These findings highlight the need for further research on weight-control medications and policies that support effective weight management while reducing depressive effects.

National trends in adolescents' mental health by income level in South Korea, pre- and post-COVID-19, 2006-2022

Despite the significant impact of the COVID-19 pandemic on various factors related to adolescent mental health problems such as stress, sadness, suicidal ideation, and suicide attempts, research on this topic has been insufficient to date. This study is based on the Korean Youth Risk Behavior Web-based Survey from 2006 to 2022. We analyzed the mental health problems of adolescents based on questionnaires with medical interviews, within five income groups and compared them with several risk factors. A total of 1,138,804 participants were included in this study, with a mean age (SD) of 15.01 (0.75) years. Of these, 587,256 were male (51.57%). In 2022, the recent period from the study, the weighted prevalence of stress in highest income group was 40.07% (95% CI, 38.67-41.48), sadness was 28.15% (26.82-29.48), suicidal ideation was 13.92% (12.87-14.97), and suicide attempts was 3.42% (2.90-3.93) while the weighted prevalence of stress in lowest income group was 62.77% (59.42-66.13), sadness was 46.83% (43.32-50.34), suicidal ideation was 31.70% (28.44-34.96), and suicide attempts was 10.45% (8.46-12.45). Lower income groups showed a higher proportion with several risk factors. Overall proportion had decreased until the onset of the pandemic. However, a significant increase has been found during the COVID-19 pandemic. Our study showed an association between household income level and the prevalence of mental illness in adolescents. Furthermore, the COVID-19 pandemic has exacerbated mental illness among adolescents from low household income level, underscoring the necessity for heightened public attention and measures targeted at this demographic.

Hand-Washing Habits in a Sample of Spanish Soft Contact Lens Wearers

Contact lens (CL) wear is a safe method for the correction of refractive errors. However, rare, severe ocular complications may occur which may lead to visual loss. As most of these complications are related to poor patient compliance with care and maintenance instructions, resulting in the contamination of hands, CLs and accessories, it was the purpose of this study to assess hand-washing habits in a sample of Spanish soft CL wearers. Hand hygiene was explored through a self-reported online survey and via an in-office practical demonstration in a subset of those users answering the survey. A total of 198 surveys were analyzed, and 18 CL users participated in the practical demonstration. Overall, hand-washing habits were not adequate, with 35 (17.8%) and 103 (52.2%) participants reporting not always washing their hands prior to CL or storage case manipulation, respectively. While 161 (81.3%) participants dried their hands after washing, 132 of these (82.1%) used non-disposable cloth towels. Participants receiving specific hand-washing information from their practitioners (141, or 71.1%) had better hand hygiene (p < 0.05). During the practical demonstration, 13 (72.2%) participants used water and soap to wash their hands, but only 3 (16.7%) displayed correct hand washing routines. Complete patient education, as well as practical reminders at all follow-up visits, are essential to ensure better hand hygiene in order to reduce the probability of ocular complications and to guarantee safe and satisfactory CL use.

National trends in type 2 diabetes mellitus stratified by central adiposity using waist-to-height ratio in South Korea, 2005-2022

Studies investigating the association between type 2 diabetes mellitus and central adiposity are lacking. Therefore, this study aimed to investigate trends in type 2 diabetes mellitus stratified by central adiposity using waist-to-height ratio (WHtR). Trends in type 2 diabetes mellitus were examined by central adiposity, using WHtR, with data from the Korea National Health and Nutrition Examination Survey (2005-2022). Individuals aged 30 years and over who participated in the survey were selected. Type 2 diabetes mellitus was identified based on serum glucose or HbA1c levels, the use of diabetes medications, or a prior diagnosis by a physician. Weighted β-coefficients or odd ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess changes in disease prevalence. A total of 79,368 participants were included in the database (female: 45,163 [56.9%]). from 2005 to 2022, the prevalence of type 2 diabetes mellitus increased from 3.3 to 5.8% in the healthy central adiposity group, from 11.2 to 17.1% in the increased central adiposity group, and from 18.0 to 26.7% in the high central adiposity group. Males, older population, lower education level, lower household income, and smoking are associated with a higher risk of type 2 diabetes. In the high central adiposity group, overweight and obese individuals had higher susceptibility than underweight or normal-weight individuals, with ORs of 5.85 (95% CI, 2.54-13.47) and 8.24 (3.79-17.94), respectively. The prevalence of type 2 diabetes mellitus has increased in all central adiposity groups in the past decade. This underscores the need for tailored interventions to address disparities and improve diabetes management in at-risk populations.

National Trends in the Prevalence of Self-Perceived Overweight Among Adolescents Between 2005 and 2022: Nationwide Representative Study

BACKGROUND

Despite several studies on self-evaluation of health and body shape, existing research on the risk factors of self-perceived overweight is insufficient, especially during the COVID-19 pandemic.

OBJECTIVE

This study aims to identify the risk factors affecting self-perceived overweight and examine how the prevalence of self-perceived overweight has changed before and during the COVID-19 pandemic. Specifically, we analyzed the impact of altered lifestyles due to COVID-19 on this phenomenon.

METHODS

The data used in the study were obtained from middle and high school students who participated in the Korean Youth Risk Behavior Web-based Survey (N=1,189,586). This survey was a 2-stage stratified cluster sampling survey representative of South Korean adolescents. We grouped the survey results by year and estimated the slope in the prevalence of self-perceived overweight before and during the pandemic using weighted linear regression, as well as the prevalence tendencies of self-perceived overweight according to various risk factors. We used prevalence ratios to identify the risk factors for self-perceived overweight. In addition, we conducted comparisons of risk factors in different periods to identify their associations with the COVID-19 pandemic.

RESULTS

The prevalence of self-perceived overweight was much higher than BMI-based overweight among 1,189,586 middle and high school participants (grade 7-12) from 2005 to 2022 (female participants: n=577,102, 48.51%). From 2005 to 2019 (prepandemic), the prevalence of self-perceived overweight increased (β=2.80, 95% CI 2.70-2.90), but from 2020 to 2022 (pandemic) it decreased (β=-0.53, 95% CI -0.74 to -0.33). During the pandemic, individuals with higher levels of stress or lower household economic status exhibited a more substantial decrease in the rate of self-perceived overweight. The prevalence of self-perceived overweight tended to be higher among individuals with poor academic performance, lower economic status, poorer subjective health, and a higher stress level.

CONCLUSIONS

Our nationwide study, conducted over 18 years, indicated that self-perceived overweight decreased during the COVID-19 period while identifying low academic performance and economic status as risk factors. These findings suggest the need for policies and facilities to address serious dieting and body dissatisfaction resulting from self-perceived overweight by developing counseling programs for adolescents with risk factors such as lower school performance and economic status.

Global public concern of childhood and adolescence suicide: a new perspective and new strategies for suicide prevention in the post-pandemic era

BACKGROUND

Suicide is the second leading cause of death in young people worldwide and is responsible for about 52,000 deaths annually in children and adolescents aged 5-19 years. Familial, social, psychological, and behavioral factors play important roles in suicide risk. As traumatic events such as the COVID-19 pandemic may contribute to suicidal behaviors in young people, there is a need to understand the current status of suicide in adolescents, including its epidemiology, associated factors, the influence of the pandemic, and management initiatives.

DATA SOURCES

We investigated global and regional suicide mortality rates among children and adolescents aged 5-19 years using data from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019. The suicide mortality rates from 1990 to 2019 were examined in 204 countries and territories across six World Health Organization (WHO) regions. Additionally, we utilized electronic databases, including PubMed/MEDLINE and Scopus, and employed various combinations of terms such as "suicide", "adolescents", "youth", "children", "risk factors", "COVID-19 pandemic", "prevention", and "intervention" to provide a narrative review on suicide within the pediatric population in the post-pandemic era.

RESULTS

Despite the decreasing trend in the global suicide mortality rate from 1990 to 2019, it remains high. The mortality rates from suicide by firearms or any other specified means were both greater in males. Additionally, Southeast Asia had the highest suicide rate among the six WHO regions. The COVID-19 pandemic seems to contribute to suicide risk in young people; thus, there is still a strong need to revisit appropriate management for suicidal children and adolescents during the pandemic.

CONCLUSIONS

The current narrative review integrates up-to-date knowledge on suicide epidemiology and the effects of the COVID-19 pandemic, risk factors, and intervention strategies. Although numerous studies have characterized trends in suicide among young people during the pre-pandemic era, further studies are required to investigate suicide during the pandemic and new strategies for suicide prevention in the post-pandemic era. It is necessary to identify effective prevention strategies targeting young people, particularly those at high risk, and successful treatment for individuals already manifesting suicidal behaviors. Care for suicidal children and adolescents should be improved with parental, school, community, and clinical involvement.

National trends in sexual intercourse and usage of contraception among Korean adolescents

BACKGROUND

The exact influence of the COVID-19 pandemic on sexual intercourse and usage of contraception remains largely uncharted territory. To bridge this gap in knowledge, we conducted a comprehensive, cross-sectional examination of long-term trends in the prevalence of sexual intercourse and usage of contraception among South Korean adolescents from 2006 to 2022.

METHODS

In our research, we drew upon data encompassing 1,138,799 South Korean adolescents aged 12 to 18 years, derived from the Korean Youth Risk Behavior Web-based Survey (KYRBS) over a period spanning from 2006 to 2022. We focused on the prevalence of sexual intercourse, contraception utilization, and the underlying associated factors among this demographic. The KYRBS data was collected using a complex sampling strategy to determine the national prevalence estimates and shifts in prevalence before (2006-2019) and during (2020-2022) the COVID-19 pandemic era.

RESULTS

During the pre-pandemic period, a decrease in adolescent sexual intercourse was observed (6.34% in 2006, 5.53% in 2012, and 5.87% in 2019). However, in the post-pandemic period (2020-2022), there was a surge in sexual intercourse (4.55% in 2020 and 6.20% in 2022). This evident alteration in sexual intercourse trajectory between pre- and post-pandemic periods was statistically significant [βdiff, 0.950; 95% confidence interval (CI), 0.756-1.144]. Regarding contraceptive use among South Korean adolescents, there was an increase in the pre-COVID-19 pandemic phase across all demographic segments (14.61% in 2006, 22.30% in 2012, and 47.69% in 2022) but a notable decline when compared with the pre- and post-pandemic periods (βdiff, - 0.319; 95% CI, - 0.454 to - 0.184). Additionally, during the study period, a decrease in sexual intercourse was observed in the pre-pandemic period (β, - 0.129; 95% CI, - 0.148 to - 0.110), followed by an increase in the post-pandemic period (β, 0.821; 95% CI, 0.627 to 1.014). This shift is highlighted by an effect size of 0.96 [weighted odds ratio (wOR); 95% CI, 0.92 to 1.00], indicating a substantial change in adolescent sexual behaviors across study periods.

CONCLUSIONS

The increase in sexual intercourse and decrease in usage of contraception observed in our study between the pre- and post-COVID-19 periods suggests a potential threat to sexual health among South Korean adolescents. This trend emphasizes the ongoing necessity of raising awareness about adolescent sexual behavior in South Korea.

Association of Soda Drinks and Fast Food with Allergic Diseases in Korean Adolescents: A Nationwide Representative Study

INTRODUCTION

A high consumption of carbonated soft drinks (i.e., soda drinks) and fast food is potentially associated with the observed global rise in adolescent allergic diseases. Thus, our study aimed to examine the potential associations between the consumption of soda drinks and fast food and allergic conditions, identifying specific relationships across subgroups and each allergic condition (asthma, allergic rhinitis, and atopic dermatitis).

METHODS

This study uses large-scale data from the Korea Youth Risk Behavior Web-Based Survey (total n = 865,614). Soda drinks and fast food were defined by a self-reported questionnaire and allergic conditions by physician-diagnosed within 1 year. Multivariable logistic regression was used to analyze the weighted odds ratios (ORs), along with 95% confidence intervals (CIs), for allergic diseases associated with the intake of soda drinks and fast food.

RESULTS

Among 865,614 adolescents in grades 7-12 (male, 51.40%), patients with asthma, allergic rhinitis, and atopic dermatitis were 18,568 (2.15%), 153,536 (17.74%), and 59,014 (6.82%), respectively. Current asthma was associated with soda drinks (OR, 1.07; 95% CI, 1.03-1.12) and fast food consumption (1.25; 1.17-1.33). Interestingly, stronger associations were observed for female high schoolers, compared to male high schoolers and middle schoolers, in relation to the consumption of soda drinks (1.31; 1.19-1.44) and fast food (1.46; 1.26-1.69) with asthma. Current allergic rhinitis and atopic dermatitis had no significant association with fast food consumption and soda drinks.

CONCLUSION

This first large-scale study suggests that fast food and soda drinks consumption are potentially associated with current asthma, with stronger associations observed in females than males, underscoring the need for sex-specific allergy prevention programs.

National prevalence of atopic dermatitis in Korean adolescents from 2009 to 2022

Previous studies have examined the prevalence of allergic diseases in adolescents 1-2 years after the emergence of the COVID-19 pandemic. However, more data is needed to understand the long-term impact of COVID-19 on allergic diseases. Thus, we aimed to examine the trend of the atopic dermatitis prevalence in Korean adolescents before and during the COVID-19 pandemic across 14 years. Additionally, we analyze the risk factors of atopic dermatitis (AD) based on the results. The Korean Disease Control and Prevention Agency conducted the Korea Youth Risk Behavior Web-based Survey from 2009 to 2022, from which the data for this study were obtained. Prevalence trends were compared across subgroups, and the β difference (βdiff) was calculated. We computed odds ratios to examine changes in the disease prevalence before and during the pandemic. This study included a total of 917,461 participants from 2009 to 2022. The prevalence of atopic dermatitis increased from 6.79% (95% CI 6.66-6.91) in 2009-2011 to 6.89% (95% CI 6.72-7.05) in 2018-2019, then decreased slightly to 5.82% (95% CI 5.60-6.04) in 2022. Across the 14 years, middle school student status, low parent's highest education level, low household income, non-alcohol consumption, non-smoker smoking status, no suicidal thoughts, and no suicide attempts were associated with increased risk of atopic dermatitis, while female sex, rural residence, high BMI, low school performance, low household income, and no feelings of sadness and despair was associated with a small increase. This study examined the prevalence of atopic dermatitis across an 18-year, and found that the prevalence increased in the pre-pandemic then decreased during the start of the pandemic and remained constant throughout the pandemic. This trend could be explained mainly by the large scale social and political changes that occurred during the COVID-19 pandemic.

Machine Learning-Based Prediction of Suicidal Thinking in Adolescents by Derivation and Validation in 3 Independent Worldwide Cohorts: Algorithm Development and Validation Study

BACKGROUND

Suicide is the second-leading cause of death among adolescents and is associated with clusters of suicides. Despite numerous studies on this preventable cause of death, the focus has primarily been on single nations and traditional statistical methods.

OBJECTIVE

This study aims to develop a predictive model for adolescent suicidal thinking using multinational data sets and machine learning (ML).

METHODS

We used data from the Korea Youth Risk Behavior Web-based Survey with 566,875 adolescents aged between 13 and 18 years and conducted external validation using the Youth Risk Behavior Survey with 103,874 adolescents and Norway's University National General Survey with 19,574 adolescents. Several tree-based ML models were developed, and feature importance and Shapley additive explanations values were analyzed to identify risk factors for adolescent suicidal thinking.

RESULTS

When trained on the Korea Youth Risk Behavior Web-based Survey data from South Korea with a 95% CI, the XGBoost model reported an area under the receiver operating characteristic (AUROC) curve of 90.06% (95% CI 89.97-90.16), displaying superior performance compared to other models. For external validation using the Youth Risk Behavior Survey data from the United States and the University National General Survey from Norway, the XGBoost model achieved AUROCs of 83.09% and 81.27%, respectively. Across all data sets, XGBoost consistently outperformed the other models with the highest AUROC score, and was selected as the optimal model. In terms of predictors of suicidal thinking, feelings of sadness and despair were the most influential, accounting for 57.4% of the impact, followed by stress status at 19.8%. This was followed by age (5.7%), household income (4%), academic achievement (3.4%), sex (2.1%), and others, which contributed less than 2% each.

CONCLUSIONS

This study used ML by integrating diverse data sets from 3 countries to address adolescent suicide. The findings highlight the important role of emotional health indicators in predicting suicidal thinking among adolescents. Specifically, sadness and despair were identified as the most significant predictors, followed by stressful conditions and age. These findings emphasize the critical need for early diagnosis and prevention of mental health issues during adolescence.

National trends of allergic diseases and pandemic-related factors among individuals with obesity in South Korea: A nationwide representative serial study, 2005-2021

Background

Although obesity is known to be related to allergic diseases, few studies have investigated the prevalence of allergic diseases in individuals with obesity, especially during the COVID-19 pandemic. Thus, this study aimed to analyze national trends of allergic diseases among individuals with obesity and sociodemographic factors.

Methods

This study used data from the Korea National Health and Nutrition Examination Survey to examine the prevalence of allergic diseases among individuals with obesity in South Korea from 2005 to 2021. A nationally representative sample of 118,275 participants aged over 2 years or above was divided into six groups for analysis. This study used weighted multivariate regression analysis to examine the estimates of related factors. It assessed the weighted odds ratios or β-coefficients for these factors across different categories, including age, sex, region of residence, education level, household income, and body mass index for the entire population.

Results

All allergic diseases showed a general upward trend from 2005 to 2021, but each disease showed different prevalence trends when compared by age. Before the pandemic, those aged ≤39 years had an increasing trend for asthma and AD, but those aged ≥40 years had a decreasing trend. For asthma, β-coefficients were 0.629 (95 % CI, 0.299 to 0.958) for 19-39 years, -0.245 (-0.450 to -0.040) for 40-59 years, and -0.668 (-1.024 to -0.313) for ≥60 years. For AD, β-coefficients were 2.514 (1.258-3.769) in those aged 2-18 years, 0.630 (0.173-1.086) in those aged 19-39 years, -0.458 (-0.648 to -0.268) in those aged 40-59 years, and -0.253 (-0.454 to -0.052) in those aged ≥60 years. However, for both asthma and AD, there were no significant changes in prevalence during the pandemic. In the case of AR, trends were different from those of asthma and AD. Before the pandemic, AR showed an increasing trend in those aged ≤39 years and those aged ≥40 years: β-coefficients were 3.067 (2.344-3.790) in 19-39 years, 2.051 (1.609-2.493) in 40-59 years, and 1.173 (0.820-1.526) in ≥60 years. During the pandemic, there was an increasing trend only among those aged 40-59, with no significant changes in other age groups: β-coefficients were 1.438 (0.065-2.811) in 40-59 years.

Conclusions

From 2005 to 2021, all allergic diseases (asthma, AD, and AR) increased overall, but with different age-related trends. No significant link was found between COVID-19 and allergic diseases, possibly due to preventive measures like mask-wearing and social distancing. Anxiety about accessing healthcare during the pandemic likely contributed to a decline in allergy diagnoses, highlighting the need for comprehensive strategies to manage and prevent allergic diseases.

National prevalence of smoking among adolescents at tobacco tax increase and COVID-19 pandemic in South Korea, 2005-2022

Prior research has predominantly focused on the overall effects of the tobacco tax increase and the COVID-19 pandemic on adolescent smoking behavior. However, there is a need to examine both the immediate and sustained associations of these two factors on subgroups of adolescents, employing an interrupted time-series model. We aimed to investigate the immediate and sustained association of tobacco tax increase and the COVID-19 pandemic on adolescent smoking prevalence. This study utilized data from the Korea Youth Risk Behavior Web-Based Survey to analyze the prevalence of current smoking among all participants (CSP) and the prevalence of daily smoking among current smokers (DSP) of Korean adolescents (n = 1,159,995; mean, age 14.99; male 51.5%) over 18 years from 2005 to 2022. The study examined 18-year trends in CSP and DSP among Korean adolescents, emphasizing the influences of the 2015 tobacco tax increase and the COVID-19 pandemic, using β coefficients and their differences (βdiff) from an interrupted time-series ARIMA model. While CSP exhibited a decreasing trend, DSP exhibited an increasing trend. Tobacco tax increase was associated with both the short and long terms in smoking prevalence, however, the short-term association on prevalence (CSP, - 3.076 [95% CI, - 3.707 to - 2.445]; DSP, - 4.112 [95% CI, - 6.488 to - 1.735]) was stronger. The pandemic was associated with an immediate increase in DSP (9.345 [95% CI, 5.285-13.406]). These effects were strongest among adolescents from low economic status and those exposed to familial secondhand smoking. Supportive programs for adolescents in low-income families will help overcome the effects associated with the pandemic. As a tobacco tax increase was associated with a reduction in smoking prevalence, this could be one method to overcome the effects of the pandemic.

Incident allergic diseases in post-COVID-19 condition: multinational cohort studies from South Korea, Japan and the UK

As mounting evidence suggests a higher incidence of adverse consequences, such as disruption of the immune system, among patients with a history of COVID-19, we aimed to investigate post-COVID-19 conditions on a comprehensive set of allergic diseases including asthma, allergic rhinitis, atopic dermatitis, and food allergy. We used nationwide claims-based cohorts in South Korea (K-CoV-N; n = 836,164; main cohort) and Japan (JMDC; n = 2,541,021; replication cohort A) and the UK Biobank cohort (UKB; n = 325,843; replication cohort B) after 1:5 propensity score matching. Among the 836,164 individuals in the main cohort (mean age, 50.25 years [SD, 13.86]; 372,914 [44.6%] women), 147,824 were infected with SARS-CoV-2 during the follow-up period (2020-2021). The risk of developing allergic diseases, beyond the first 30 days of diagnosis of COVID-19, significantly increased (HR, 1.20; 95% CI, 1.13-1.27), notably in asthma (HR, 2.25; 95% CI, 1.80-2.83) and allergic rhinitis (HR, 1.23; 95% CI, 1.15-1.32). This risk gradually decreased over time, but it persisted throughout the follow-up period (≥6 months). In addition, the risk increased with increasing severity of COVID-19. Notably, COVID-19 vaccination of at least two doses had a protective effect against subsequent allergic diseases (HR, 0.81; 95% CI, 0.68-0.96). Similar findings were reported in the replication cohorts A and B. Although the potential for misclassification of pre-existing allergic conditions as incident diseases remains a limitation, ethnic diversity for evidence of incident allergic diseases in post-COVID-19 condition has been validated by utilizing multinational and independent population-based cohorts.

Prenatal and postnatal exposure to antibiotics and risk of food allergy in the offspring: A nationwide birth cohort study in South Korea

BACKGROUND

There are only preliminary studies examining the associations of postnatal antibiotic exposure with food allergy in childhood, and the effect of antibiotic exposure in utero has not been resolved. Thus, we aimed to investigate the effect of prenatal and postnatal antibiotic exposure on the risk of food allergy in childhood.

METHODS

Using the nationwide birth cohort in South Korea, all 3,163,206 infants (pairing mother; n = 2,322,735) born in South Korea between 2010 and 2017 were included in the analysis. The primary outcome was the diagnosis of food allergy, and the observation period was between January 1, 2009, and December 31, 2020. We implemented four different designs for the study, which consisted of a full unmatched cohort, 1:1 propensity-matched cohort, sibling comparison cohort, and health screening cohort along with multiple subgroup analyses.

RESULTS

During the follow-up period (median 6.92 years [IQR, 4.72-9.00]) of the 3,161,858 infants (52.6% male) in the birth cohort, 29,973 (1.9%) were diagnosed with food allergies. After a 1:1 propensity score matching, the use of antibiotics increased the risk of overall food allergy (prenatal [HR, 1.05; 95% CI, 1.04-1.09] and postnatal [HR, 1.05; 95% CI, 1.01-1.10] periods). The association was more significantly accentuated when antibiotic exposure was used in the short term, and the children were born preterm or with low birthweight; however, a trimester-specific effect was not observed. We observed more pronounced risks of food allergy in the health screening cohort (prenatal, 17%; postnatal, 15%), thus addressing the adverse effects of critical factors including maternal BMI, smoking status, and type of infant feeding. Similar trends were observed across all four differnt cohorts.

CONCLUSION

This study reported a moderate association between early-life antibiotic use and subsequent food allergy during childhood throughout four different designs of analyses. This study suggests that clinicians need to consider the risks and benefits of antibiotics when administering antibiotics to individuals in the prenatal and postnatal periods.

Disparities in Health and Oral Health Behaviors Among Adolescents from Multicultural Families in South Korea

This study analyzed changes over time in order to identify disparities in health and oral health behaviors among adolescents from multicultural families residing in Korea. This was a cross-sectional analysis of secondary data utilizing raw data from 2011 to 2022 from the Korea Youth Risk Behavior Survey, a statistical dataset provided by the Korea Disease Control and Prevention Agency. The variables included demographic characteristics, socioeconomic characteristics, health behavior (diet, alcohol consumption, smoking), and oral health behavior (toothbrushing behavior, preventive care behavior, oral symptom experience, and school-based oral health education experience). In comparison to non-multicultural adolescents, multicultural adolescents were more likely to perceive their oral health behavior as unhealthy and less likely to engage in toothbrushing after lunch. In addition, multicultural adolescents had higher rates of soda intake and smoking experience than non-multicultural adolescents. During the period between 2011 and 2022, multicultural adolescents had less experience of dental sealants and scaling than non-multicultural adolescents. The disparities in health status and oral health behavior between the 2 groups persisted over a 12-year period. It was necessary to develop active interventions to reduce health and oral health disparities between multicultural and non-multicultural adolescents.