Epidemiology and Health

Volume 46; 2024

Original Articles

Associations of active and passive tobacco exposure with elevated blood pressure in Korean adolescents: Hyerin Park, Hyunsuk Jeong, Hyeon Woo Yim, Sanghyuk Bae; Epidemiol Health. 2024;46:e2024028. Published online February 13, 2024; DOI: https://doi.org/10.4178/epih.e2024028

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Abstract Summary PDF Supplementary Material: Abstract
OBJECTIVES
To test the hypothesis that tobacco exposure is associated with elevated blood pressure (EBP) in Korean adolescents, and that the association is dose dependent.
METHODS
This cross-sectional study used data from the 2011-2020 Korea National Health and Nutrition Survey (KNHANES). Subjects were eligible if they were 13-18 years at the time of participation in KNHANES. Tobacco exposure was defined by urine cotinine level. The main outcomes were EBP and hypertension. Statistical analyses were conducted using SAS version 9.4 with appropriate sampling weights to account for the complex survey design, stratification, and cluster variable.
RESULTS
A total of 2,518 adolescents was included in the analysis, representing 2.5 million Korean adolescents. The mean± standard deviation participant age was 15.3±1.7 years, and 55.3% were male. The number of participants with active tobacco smoke exposure was 283 (11.2%), passive tobacco smoke exposure was 145 (5.8%), and no smoke exposure was 2,090 (83.0%). Analysis of the 2,518 urine-cotinine-verified participants showed that tobacco smoke exposure had a significant effect on EBP: with an odds of elevated blood pressure of 3.00 (95% confidence interval [CI], 1.14 to 7.89). The odds of hypertension were 3.61 (95% CI, 1.13 to 11.49) in the active smoking group compared with the no tobacco exposure group after adjustment for potential confounders.
CONCLUSIONS
It is necessary to present a range of public health plans to reduce tobacco exposure that affects adolescents’ blood pressure, and further research with a larger number of participants using urine cotinine as a biomarker is needed.; Summary

Korean summary
청소년기의 고혈압은 성인기의 다양한 질병을 초래할 수 있는 주요 원인이다. 흡연과 고혈압의 관계에 관한 다수의 연구들이 있으나 상반된 결과들이 보고되었고 국내 청소년의 직 간접적 담배 연기 노출과 혈압과의 연관성은 명확하게 밝혀지지 않았다. 따라서 본 연구에서는 한국 청소년에서 담배 연기 노출과 혈압 상승과의 연관성을 확인해 보고자 하였다. 연구 결과 직접 흡연을 하는 청소년들은 비흡연군에 비하여 3배 이상 혈압이 증가하는 것으로 나타났다.

Key Message
Hypertension during adolescence is a leading cause of disease in adults. The relationship between smoking and hypertension has been studied, but findings between studies are conflicting. Nicotine is a known toxin, but the relationship between active and passive smoking and blood pressure in adolescents is not clear. So that we tested and found adolescents in Korea who were active smokers showed over 3-fold increased risk of elevated blood pressure.

Associations of depressive symptoms with lower extremity function and balance in Korean older adults: Bong Jo Kim, Kyupin Ha, Hyun Soo Kim, Hye Ran Bae, Minkook Son; Epidemiol Health. 2024;46:e2024021. Published online January 15, 2024; DOI: https://doi.org/10.4178/epih.e2024021

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Abstract PDF: Abstract
OBJECTIVES
The relationship of depressive symptoms to lower extremity function and balance, especially in older adults without a depression diagnosis, remains unclear. Therefore, our study analyzed this relationship using a large sample of Korean older adults.
METHODS
We used data from the Korean National Health Insurance Service’s Health Screening Program database. Individuals aged 66 years who had undergone the National Screening Program for Transitional Ages in Korea and were without a diagnosis of depressive disorder were included. The lower extremity function and balance were evaluated using 2 physical tests, while depressive symptoms were assessed using a 3-question survey. Multivariable-adjusted logistic regression analysis was used to examine the association between depressive symptoms and lower extremity function and balance.
RESULTS
Among 66,041 individuals, those with depressive symptoms showed significantly higher rates of abnormal lower extremity function and abnormal balance. The adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for the association of depressive symptoms to abnormal lower extremity function and abnormal balance were (aOR, 1.34; 95% CI, 1.25 to 1.44) and (aOR, 1.38; 95% CI, 1.29 to 1.48), respectively. Assessment of the relationship based on depressive symptom scores revealed that higher scores were associated with higher aORs (p for trend <0.001). Subgroup analyses further confirmed this relationship, especially among patients with cerebrovascular disease or dementia.
CONCLUSIONS
This study revealed an association between depressive symptoms and the abnormal lower extremity function and balance of 66-year-old individuals without a diagnosis of depressive disorder.; Summary

Association of plain water intake with self-reported depression and suicidality among Korean adolescents: Jung Woo Lee, Yookyung Kim; Epidemiol Health. 2024;46:e2024019. Published online January 9, 2024; DOI: https://doi.org/10.4178/epih.e2024019

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Abstract Summary PDF: Abstract
OBJECTIVES
Adolescent depression and suicidality are serious health problems worldwide. Lower plain water intake has been proposed as a risk factor for depression in adults. This study investigated the association of daily plain water intake with self-reported depression and suicidality among Korean adolescents.
METHODS
We used nationwide data from 112,250 students aged 12-18 years who participated in the Korean Youth Risk Behavior Web-based Surveys in 2019 and 2020. Daily plain water intake was categorized as <1 glass, 1-2 glasses, and ≥3 glasses. The adjusted odds ratios (aORs) with 95% confidence intervals (CIs) for self-reported depression and suicidality were calculated using multiple regression analyses.
RESULTS
The weighted prevalence rates of self-reported depression, suicidal ideation, suicide planning, and suicide attempts were 26.7%, 12.0%, 3.8%, and 2.5%, respectively. Of the participants, 3.9%, 18.5%, and 77.7% were categorized into the <1 glass/day, 1-2 glass/day, and ≥3 glass/day groups, respectively. Compared to the reference group (≥3 glass/day), the lowest level of water intake (<1 glass/day) was associated with higher odds of self-reported depression (aOR, 1.30; 95% CI, 1.20 to 1.39), suicidal ideation (aOR, 1.39; 95% CI, 1.27 to 1.55), suicide planning (aOR, 1.46; 95% CI, 1.25 to 1.69), and suicide attempts (aOR, 1.38; 95% CI, 1.15 to 1.67). Moderately lower water intake (1-2 glass/day) showed slightly increased odds of self-reported depression (aOR, 1.05; 95% CI, 1.01 to 1.10) and suicidal ideation (aOR, 1.08; 95% CI, 1.03 to 1.14).
CONCLUSIONS
Lower plain water intake was significantly associated with a higher risk of self-reported depression and suicidality among Korean adolescents. Since this cross-sectional study is unable to establish a causal relationship, it underscores the need for additional longitudinal research.; Summary

Korean summary
- 한국 청소년들에서 하루 물 섭취량이 적을수록 스스로 느끼는 우울감과 자살성향 위험이 증가하였다. - 이 연구는 하루 물 섭취량 측정이 청소년 우울증과 자살성향을 선별할 수 있음을 시사한다.

Key Message
- Lower daily plain water intake is significantly associated with a higher risk of self-reported depression and suicidality in Korean adolescents. - It suggests that daily plain water consumption could potentially serve as a screening indicator to identify depression and suicidality in adolescents.

A prospective association between dietary mushroom intake and the risk of type 2 diabetes: the Korean Genome and Epidemiology Study–Cardiovascular Disease Association Study: Yu-Mi Kim, Hye Won Woo, Min-Ho Shin, Sang Baek Koh, Hyeon Chang Kim, Mi Kyung Kim; Epidemiol Health. 2024;46:e2024017. Published online January 8, 2024; DOI: https://doi.org/10.4178/epih.e2024017

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Abstract Summary PDF Supplementary Material: Abstract
OBJECTIVES
Mushrooms, known for their nutritious and functional components, are considered healthy and medicinal. This study investigated the prospective association between dietary mushroom consumption and the incidence of type 2 diabetes among Korean adults aged ≥40 years.
METHODS
In total, 16,666 participants who were not taking anti-diabetic medication or insulin and had normal fasting blood glucose (FBG; <126 mg/dL) were included. We used the cumulative average dietary consumption of mushrooms as an exposure metric, calculated from food frequency questionnaires at every follow-up, along with covariates collected during a baseline survey. To estimate incidence rate ratios (IRRs) for type 2 diabetes, a modified Poisson regression model with a robust error estimator was applied.
RESULTS
In multivariable models, dietary mushroom consumption was inversely associated with type 2 diabetes incidence in both genders (men: IRR, 0.65; 95% confidence interval [CI], 0.47 to 0.90; p<sub>linearity</sub>=0.043 in the highest quartile (Q4) vs. the lowest quartile (Q1); women: IRR, 0.70; 95% CI, 0.54 to 0.93; p<sub>linearity</sub>=0.114 in Q4 vs. Q1). The inverse association remained after adjustment for dietary factors instead of dietary quality index, the baseline FBG, and the exclusion of incidence within the first year. Additionally, no significant interaction was found regarding the risk of type 2 diabetes between dietary mushroom consumption and participants’ gender or other factors.
CONCLUSIONS
Dietary mushroom consumption was inversely linked with the risk of type 2 diabetes incidence in both genders, indicating the beneficial role of mushrooms in preventing the disease.; Summary

Korean summary
- 흔히 사용하는 버섯의 식이 섭취량이 증가함에 따라 한국 40세 이상 성인에서 제2형 당뇨병 발생 위험이 낮았다. - 이러한 역관계는 성별과 다양한 식이 배경에서도 일관성을 유지하였고, 이는 버섯이 제2형 당뇨병 예방에 있어 잠재적인 식이요소로서의 가능성을 보여주는성을 보여주는 보여주는 결과이다.

Key Message
• Increased dietary consumption of commonly used mushrooms is associated with a lower risk of type 2 diabetes incidence among adults aged 40 years or older in Korea. • This inverse relationship remains consistent across genders and various dietary backgrounds, underscoring the potential of mushrooms as a preventive dietary component against.

COVID-19: Original Article

The bounds of meta-analytics and an alternative method: Ramalingam Shanmugam, Mohammad Tabatabai, Derek Wilus, Karan P. Singh; Epidemiol Health. 2024;46:e2024016. Published online January 7, 2024; DOI: https://doi.org/10.4178/epih.e2024016

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Abstract Summary PDF Supplementary Material: Abstract
OBJECTIVES
Meta-analysis is a statistical appraisal of the data analytic implications of published articles (Y), estimating parameters including the odds ratio and relative risk. This information is helpful for evaluating the significance of the findings. The Higgins I2 index is often used to measure heterogeneity among studies. The objectives of this article are to amend the Higgins I2 index score in a novel and innovative way and to make it more useful in practice.
METHODS
Heterogeneity among study populations can be affected by many sources, including the sample size and study design. They influence the Cochran Q score and, thus, the Higgins I2 score. In this regard, the I2 score is not an absolute indicator of heterogeneity. Q changes by bound as Y increases unboundedly. An innovative methodology is devised to show the conditional and unconditional probability structures.
RESULTS
Various properties are derived, including showing that a zero correlation between Q and Y does not necessarily mean that they are independent. A new alternative statistic, S2, is derived and applied to mild cognitive impairment and coronavirus disease 2019 vaccination for meta-analysis.
CONCLUSIONS
A hidden shortcoming of the Higgins I2 index is overcome in this article by amending the Higgins I2 score. The usefulness of the proposed methodology is illustrated using 2 examples. The findings have potential health policy implications.; Summary

Key Message
An approach to overcome the hidden shortcomings of Higgens I2 in meta-analysis. The approach has potential health policy implications.

Original Articles

An epidemic of cataract surgery in Korea: the effects of private health insurance on the National Health Insurance Service: Hyejin Lee, Soo-Hee Hwang, Choon-Seon Park, Seol-Hee Chung, Catherine L. Chen, Jin Yong Lee, Jin Soo Lee; Epidemiol Health. 2024;46:e2024015. Published online January 6, 2024; DOI: https://doi.org/10.4178/epih.e2024015

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Abstract Summary PDF: Abstract
OBJECTIVES
In Korea, the National Health Insurance Service (NHIS) covers essential healthcare expenses, including cataract surgery. To address concerns that private health insurance (PHI) might have inflated the need for such procedures, we investigated the extent of the PHI-attributable increase in cataract surgery and its impact on NHIS-reimbursed expenses.
METHODS
This retrospective, observational study uses nationwide claims data for cataract surgery from 2016 to 2020. We examined trends in utilization and cost, and we estimated the excess numbers of (1) cataract operations attributable to PHI and (2) types of intraocular lenses used for cataract surgery in 2020.
RESULTS
Between 2016 and 2020, a 36.8% increase occurred in the number of cataract operations, with increases of 63.5% and 731.8% in the total healthcare costs reimbursed by NHIS and PHI, respectively. Over a 5-year period, the surgical rate per 100,000 people doubled for patients aged <65 years (from 328 in 2016 to 664 in 2020). Among the 619,771 cases in 2020 of cataract surgery reimbursed by the Korean diagnosis-related group system, more non-NHIS-covered intraocular lenses were used for patients aged <65 years than ≥65 years (68.1 vs. 14.2%). In 2020 alone, an estimated 129,311 excess operations occurred, accounting for an excess cost of US$115 million.
CONCLUSIONS
A dramatic increase in the number and cost of cataract operations has occurred over the last 5 years. The PHI-related increase in operations resulted in increased costs to NHIS. Measures to curtail the non-indicated use of cataract surgery should be implemented regarding PHI.; Summary

Korean summary
백내장 수술에서 실손보험으로 인한 의료비 증가 수준을 확인하고 건강보험급여 비용에 미치는 영향을 조사했을 때 2016년과 2020년 사이에 백내장 수술 건수는 36.8% 증가했으며, 건강보험과 실손보험에서 지급한 총 의료 비용은 각각 63.5%와 731.8% 증가했다. 백내장 수술은 65세 미만에서 주로 증가하였으며, 이 연령층은 공단에서 급여하지 않는 고가의 인공수정체를 더 많이 사용하였다. 추정 초과 수술 건수는 2020년에만 129,311건으로 1억 1,500만 달러의 초과 비용이 발생했다.

Determinants of unhealthy living by gender, age group, and chronic health conditions across districts in Korea using the 2010-2017 Community Health Surveys: Thi Tra Bui, Thi Huyen Trang Nguyen, Jinhee Lee, Sun Young Kim, Jin-Kyoung Oh; Epidemiol Health. 2024;46:e2024014. Published online January 4, 2024; DOI: https://doi.org/10.4178/epih.e2024014

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Abstract Summary PDF Supplementary Material: Abstract
OBJECTIVES
We investigated the prevalence and determinants of unhealthy living by gender, age, and comorbidities across Korean districts.
METHODS
For 806,246 men and 923,260 women from 245 districts who participated in the 2010-2017 Korean Community Health Surveys, risk scores were calculated based on obesity, physical inactivity, smoking, and high-risk alcohol consumption, each scored from 0 (lowest risk) to 2 (highest risk). A risk score ≥4 was defined as indicating unhealthy living, and weighted proportions were calculated for each district. Using multivariate regression, an ecological model including community socioeconomic, interpersonal, and neighborhood factors was examined by gender, age, and comorbidities.
RESULTS
The mean age-standardized rate of unhealthy living was 24.05% for men and 4.91% for women (coefficients of variation, 13.94% and 29.51%, respectively). Individuals with chronic diseases more frequently exhibited unhealthy lifestyles. Unhealthy lifestyles were associated with educational attainment (β-coefficients: men, -0.21; women, -0.15), high household income (β=0.08 and 0.03, respectively), pub density (β=0.52 and 0.22, respectively), and fast-food outlet density (β=2.81 and 1.63, respectively). Negative associations were observed with manual labor, social activity participation, and hospital bed density. Unhealthy living was positively associated with living alone among women and with being unemployed among middle-aged men. Access to parks was negatively associated with unhealthy living among young men and women. The ecological model explained 32% of regional variation in men and 41% in women.
CONCLUSIONS
Improving the neighborhood built and socioeconomic environment may reduce regional disparities in lifestyle behaviors; however, the impacts may vary according to socio-demographic traits and comorbidities.; Summary

Korean summary
- 시군구 지역단위의 불건강생활(흡연, 음주, 비만, 신체활동 부족 각 0-2점, 합 4점 이상 불건강) 유병률은 여자보다 남자에서 높고, 연령이 높아지면서 감소한다. - 지역사회 환경개선(술집 개수, 패스트푸드점 밀도, 공원 면적, 병상밀도)과 사회경제적 수준 강화(교육수준, 가구소득, 고용)를 통해 생활습관적 건강행태의 지역 격차를 줄일 수 있다. - 이러한 향상 노력의 효과는 지역의 건강상태 수준이나 사회인구학적 특성에 따라 다를 수 있다.

Key Message
• District prevalence rates of unhealthy living were higher among men than women and decreased with advancing age. • Efforts to reduce regional disparities in lifestyle behaviors could benefit from enhancements to the neighborhood environment and the socioeconomic status of the area. • The effectiveness of such improvements may vary based on socio-demographic characteristics and health conditions.

Systematic Review

Effectiveness of community-based interventions for older adults living alone: a systematic review and meta-analysis: Inhye Kim, Hyunseo An, Sohyeon Yun, Hae Yean Park; Epidemiol Health. 2024;46:e2024013. Published online January 3, 2024; DOI: https://doi.org/10.4178/epih.e2024013

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Abstract Summary PDF Supplementary Material: Abstract
OBJECTIVES
This study examined the effectiveness of community-based interventions designed for older adults living alone through a systematic review and meta-analysis.
METHODS
The study incorporated 4 randomized controlled trials (RCTs) and 5 non-RCTs to evaluate various interventions. The methodological quality of these studies was assessed using the Downs and Black checklist, while Q-statistic and I-square tests were performed to examine statistical heterogeneity. Additionally, visual inspection of funnel plots and the trim-and-fill method were employed to investigate potential publication bias. Of the 2,729 identified studies, 9 met the criteria for inclusion in this review. Independent variables were categorized into 5 groups (physical activity, nutrition, social relationships, social participation, and combined intervention) to examine their effects. Dependent variables were similarly classified into 5 subgroups to identify the specific effects of the interventions.
RESULTS
Interventions focusing on nutrition and combined approaches were the most effective, yielding effect sizes of 0.96 (95% confidence interval [CI], 0.66 to 1.25) and 0.43 (95% CI, 0.26 to 0.60), respectively. The interventions had the greatest impacts on the health behavior and mental health of the participants, with effect sizes of 0.98 (95% CI, 0.73 to 1.22) for health behavior and 0.67 (95% CI, 0.19 to 1.16) for mental health.
CONCLUSIONS
This study suggests a direction for the development of community-based interventions tailored to the needs of older adults living alone. Additionally, it provides evidence to inform policy decisions concerning this demographic.; Summary

Korean summary
본 연구는 독거 노인들 대상으로 한 지역사회 기반 중재의 효과에 대하여 탐색하고 그 효과 크기를 확인하기 위하여 체계적고찰 및 메타분석을 실시하였다. 영양 및 복합 중재가 특히 효과적이었으며, 이는 건강 행동과 정신건강에 있어 중요한 긍정적 효과를 나타내어 추후 개별적 맞춤 중재의 잠재적 효과성을 나타낸다. 이러한 발견은 독거노인 집단의 웰빙 향상을 위한 프로그램과 정책 입안에 근거로 활용될 수 있다.

Key Message
This systematic review and meta-analysis evaluated the impact of community-based interventions for older adults living alone, incorporating 9 studies to assess effectiveness in areas like nutrition and combined strategies. Results indicated significant benefits, particularly in health behavior and mental health, demonstrating the potential of tailored interventions. These findings support the development of targeted programs and policy decisions aimed at improving the well-being of this demographic.

Original Articles

Identifying pregnancy episodes and estimating the last menstrual period using an administrative database in Korea: an application to patients with systemic lupus erythematosus: Yu-Seon Jung, Yeo-Jin Song, Jihyun Keum, Ju Won Lee, Eun Jin Jang, Soo-Kyung Cho, Yoon-Kyoung Sung, Sun-Young Jung; Epidemiol Health. 2024;46:e2024012. Published online December 19, 2023; DOI: https://doi.org/10.4178/epih.e2024012

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Abstract Summary PDF Supplementary Material: Abstract
OBJECTIVES
This study developed an algorithm for identifying pregnancy episodes and estimating the last menstrual period (LMP) in an administrative claims database and applied it to investigate the use of pregnancy-incompatible immunosuppressants among pregnant women with systemic lupus erythematosus (SLE).
METHODS
An algorithm was developed and applied to a nationwide claims database in Korea. Pregnancy episodes were identified using a hierarchy of pregnancy outcomes and clinically plausible periods for subsequent episodes. The LMP was estimated using preterm delivery, sonography, and abortion procedure codes. Otherwise, outcome-specific estimates were applied, assigning a fixed gestational age to the corresponding pregnancy outcome. The algorithm was used to examine the prevalence of pregnancies and utilization of pregnancy-incompatible immunosuppressants (cyclophosphamide [CYC]/mycophenolate mofetil [MMF]/methotrexate [MTX]) and non-steroidal anti-inflammatory drugs (NSAIDs) during pregnancy in SLE patients.
RESULTS
The pregnancy outcomes identified in SLE patients included live births (67%), stillbirths (2%), and abortions (31%). The LMP was mostly estimated with outcome-specific estimates for full-term births (92.3%) and using sonography procedure codes (54.7%) and preterm delivery diagnosis codes (37.9%) for preterm births. The use of CYC/MMF/MTX decreased from 7.6% during preconception to 0.2% at the end of pregnancy. CYC/MMF/MTX use was observed in 3.6% of women within 3 months preconception and 2.5% during 0-7 weeks of pregnancy.
CONCLUSIONS
This study presents the first pregnancy algorithm using a Korean administrative claims database. Although further validation is necessary, this study provides a foundation for evaluating the safety of medications during pregnancy using secondary databases in Korea, especially for rare diseases.; Summary

Korean summary
임산부의 약물 사용 안전성에 대한 근거 제공을 위해 실제 인구집단에서의 임신 중 약물 치료 안전성을 평가하는 청구자료 기반 연구가 중요하다. 본 연구에서는 국내 청구자료에 적용할 수 있는 임신 정의 및 임신 결과 조작적 정의 알고리즘을 개발하였다. 본 알고리즘은 임신 결과 간의 우선순위를 고려한 계층 구조를 활용하며, 조기 분만 및 초음파 검사 코드 등을 통해 최종 월경 기간을 추정하였다. 또한 알고리즘을 전신홍반루푸스 환자에 적용하여 유산, 사산 등의 유병률을 산출하고 임신 중 잠재적으로 부적절한 면역억제제 사용을 파악하여 국내 청구자료의 특성을 고려한 임신 중 약물 사용 연구의 기반을 마련하였다.

Key Message
Limited safety data for pregnant women prompted recent studies on medication during pregnancy using real-world databases. This study developed a tailored algorithm for Korean healthcare claims database, employing a hierarchy of pregnancy outcomes and incorporating pre-term delivery and sonography codes for last menstrual period estimation. Applied to systemic lupus erythematosus (SLE) patients, this study presented the prevalence and drug utilization pattern of pregnancy-incompatible immunosuppressants from preconception to pregnancy end, laying a foundation for further claims database studies on medication pregnancy safety.

The association between migraine and Parkinson’s disease: a nationwide cohort study in Korea: Woo-Seok Ha, Jaeho Kim, Hee Won Hwang, Sue Hyun Lee, Ji In Kim, Jin Yong Hong, Sang Hyun Park, Kyung Do Han, Min Seok Baek; Epidemiol Health. 2024;46:e2024010. Published online December 18, 2023; DOI: https://doi.org/10.4178/epih.e2024010

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Abstract Summary PDF Supplementary Material: Abstract
OBJECTIVES
Clinical studies have suggested an association between migraine and the occurrence of Parkinson’s disease (PD). However, it is unknown whether migraine affects PD risk. We aimed to investigate the incidence of PD in patients with migraine and to determine the risk factors affecting the association between migraine and PD incidence.
METHODS
Using the Korean National Health Insurance System database (2002-2019), we enrolled all Koreans aged ≥40 years who participated in the national health screening program in 2009. International Classification of Diseases (10th revision) diagnostic codes and Rare Incurable Diseases System diagnostic codes were used to define patients with migraine (within 12 months of enrollment) and newly diagnosed PD.
RESULTS
We included 214,193 patients with migraine and 5,879,711 individuals without migraine. During 9.1 years of follow-up (55,435,626 person-years), 1,973 (0.92%) and 30,664 (0.52%) individuals with and without migraine, respectively, were newly diagnosed with PD. Following covariate adjustment, patients with migraine showed a 1.35-fold higher PD risk than individuals without migraine. The incidence of PD was not significantly different between patients with migraine with aura and those without aura. In males with migraine, underlying dyslipidemia increased the risk of PD (p=0.012). In contrast, among females with migraine, younger age (<65 years) increased the risk of PD (p=0.038).
CONCLUSIONS
Patients with migraine were more likely to develop PD than individuals without migraine. Preventive management of underlying comorbidities and chronic migraine may affect the incidence of PD in these patients. Future prospective randomized clinical trials are warranted to clarify this association.; Summary

Korean summary
편두통 환자들은 편두통이 없는 이들보다 장기적으로 파킨슨병이 발병할 위험이 더 높습니다. 더불어, 이 관계는 편두통의 아형(전조 vs. 무전조)보다는 편두통의 빈도(삽화성 vs. 만성)와 더 밀접한 연관성을 갖는 것으로 보입니다.

Key Message
Patients with migraine are more likely to develop Parkinson’s disease than individuals without migraine. Furthermore, this association appears to be more strongly linked to the frequency of migraines (episodic vs. chronic) rather than the subtype of migraine (with aura vs. without aura).

Decrease in household secondhand smoking among Korean adolescents associated with smoke-free policies: grade-period-cohort and interrupted time series analyses: Hana Kim, Heewon Kang, Sung-il Cho; Epidemiol Health. 2024;46:e2024009. Published online December 13, 2023; DOI: https://doi.org/10.4178/epih.e2024009

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Abstract Summary PDF Supplementary Material: Abstract
OBJECTIVES
Smoke-free areas have expanded and related campaigns have been implemented since 1995 in Korea. As a result, household secondhand smoke (SHS) exposure has decreased over the past 15 years. We assessed the cohort effect, the effect of a 2008 campaign on household SHS exposure, and the impact of a complete smoking ban in public places along with increased penalties, as implemented in December 2011.
METHODS
Nationally representative cross-sectional 15-wave survey data of Korean adolescents were used. The 810,516 participants were classified into 6 grade groups, 15 period groups, and 20 middle school admission cohorts. An age-period-cohort analysis, conducted with the intrinsic estimator method, was used to assess the cohort effect of household SHS exposure, and interrupted-time series analyses were conducted to evaluate the effects of the smoke-free policy and the campaign.
RESULTS
For cohorts who entered middle school from 2002 to 2008, the risk of household SHS exposure decreased among both boys and girls. Immediately after implementation of the smoke-free policy, the prevalence of household SHS exposure by period decreased significantly for boys (coefficient, -8.96; p<0.05) and non-significantly for girls (coefficient, -6.99; p=0.07). After the campaign, there was a significant decrease in household SHS exposure by cohort among boys, both immediately and post-intervention (coefficient, -4.84; p=0.03; coefficient, -1.22; p=0.02, respectively).
CONCLUSIONS
A school-admission-cohort effect was found on household SHS exposure among adolescents, which was associated with the smoke-free policy and the campaign. Anti-smoking interventions should be implemented consistently and simultaneously.; Summary

Korean summary
지난 15년 동안 한국 청소년의 가정 내 간접흡연 노출은 감소했다. 가정 내 간접흡연 노출에 대하여 중학교 입학 코호트 효과가 존재하였다. 또한, 청소년의 가정 내 간접흡연 노출 감소는 2011년 12월 공공장소에서의 금연구역 규제와 2008년 시행된 캠페인과 연관되어 있었다.

Key Message
Household secondhand smoke (SHS) exposure among Korean adolescents has decreased over the past 15 years. There was a school admission cohort effect on household SHS exposure. A complete smoking ban in public space with increased penalties in December 2011 and a campaign in 2008 to avoid SHS exposure were associated with reduced household SHS exposure among adolescents.

Validation of the Korean Academy of Geriatric Dentistry screening questionnaire and oral frailty diagnostic criteria in community-dwelling older adults: Jeong-Hyun Kang, Seong-Chan Park, Hoi-In Jung, Sun Jae Jung, Hye-Jin Park, Soo-Min Kim, Min-Ji Jo, Yun-Seon Lee, Sun-Young Han; Epidemiol Health. 2024;46:e2024008. Published online December 11, 2023; DOI: https://doi.org/10.4178/epih.e2024008

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Abstract Summary PDF Supplementary Material: Abstract
OBJECTIVES
This study aimed to establish the validity—specifically, the sensitivity and specificity—of the screening questionnaire and diagnostic criteria for oral frailty proposed by the Korean Academy of Geriatric Dentistry (KAGD) among community-dwelling older adults.
METHODS
This study enrolled 100 participants. Among various definitions of oral frailty, this study used the criteria proposed by Tanaka as the reference test. The screening questionnaire consisted of 11 items for screening physical frailty, chewing ability, swallowing difficulties, oral dryness, and tongue and lip motor function. Each question had a different scoring weight, and if the total score was 1 or higher, an oral frailty diagnostic examination proposed by the KAGD would be recommended. The diagnostic test was the oral frailty diagnostic criteria proposed by the KAGD including 6 measures: chewing ability, occlusal force, tongue pressure, oral dryness, swallowing difficulty, and oral hygiene. If a participant exhibited 2 or more positive measures, this participant was classified as “oral frail.” The screening questionnaire was analyzed using a cut-off value of 1 or higher, while the diagnostic criteria utilized a cut-off of 2 or more positive measures. Sensitivity and specificity were calculated.
RESULTS
The screening questionnaire showed significant power for screening oral frailty (area under the receiver operating characteristic curve, 0.783; sensitivity, 87.8%; specificity, 52.5%). The diagnostic accuracy of the newly proposed diagnostic criteria was acceptable (sensitivity, 95.1%; specificity, 42.4%).
CONCLUSIONS
The newly proposed screening questionnaire and diagnostic criteria in Korea appear to be a useful tool to identify oral frailty in community-dwelling older adults.; Summary

Korean summary
본 연구는 지역사회에 거주하는 노인들의 구강 노쇠에 대한 선별검사 설문지와 진단 기준을 검증하는 것을 목표로 했습니다. 민감도와 특이도가 계산되었으며, 스크리닝 설문지는 구강 노쇠를 식별하는 데 상당한 힘을 보여주었고(민감도 87.8%, 특이도 52.5%), 진단 기준은 수용 가능한 정확도(민감도 95.1%, 특이도 42.4%)를 나타냈습니다. 연구 결과는 제안된 선별 설문지와 진단 기준이 한국 지역사회에 거주하는 노인들의 구강 노쇠를 식별하는 데 유용한 도구임을 시사합니다.

Key Message
This study aimed to validate a screening questionnaire and diagnostic criteria for oral frailty among older adults living in the community. Sensitivity and specificity were calculated, with the screening questionnaire demonstrating a significant power for identifying oral frailty (sensitivity 87.8%, specificity 52.5%) and the diagnostic criteria showing acceptable accuracy (sensitivity 95.1%, specificity 42.4%). The findings suggest that the proposed screening questionnaire and diagnostic criteria are valuable tools for identifying oral frailty in community-dwelling older adults in Korea.

Folate, vitamin B12, and homocysteine status in the Korean population: data from the 2013-2015 Korea National Health and Nutrition Examination Survey: Sihan Song, Bo Mi Song, Hyun-Young Park; Epidemiol Health. 2024;46:e2024007. Published online December 11, 2023; DOI: https://doi.org/10.4178/epih.e2024007

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Abstract Summary PDF Supplementary Material: Abstract
OBJECTIVES
We aimed to assess the serum folate, vitamin B12, and homocysteine status in Korean adolescents and adults using national data.
METHODS
Blood samples were collected from participants aged ≥10 years in the Korea National Health and Nutrition Examination Survey 2013-2015. The stored serum samples were used to measure folate, vitamin B12, and homocysteine concentrations. A total of 8,016 participants were included in this analysis. Unweighted descriptive statistics and adjusted geometric means of the B vitamins and homocysteine concentrations were estimated.
RESULTS
Females had higher serum folate and vitamin B12 concentrations and lower serum homocysteine concentrations than males. Folate deficiency (<6.8 nmol/L) and hyperhomocysteinemia (>15 μmol/L) were found in 8.6% and 11.8% of males, respectively. Approximately 3% of males had low or marginally low vitamin B12 status (≤221 pmol/L). Folate and vitamin B12 deficiencies and hyperhomocysteinemia were found in <2% of females. Suboptimal folate status was prevalent among adolescents and young adults, while suboptimal vitamin B12 status and hyperhomocysteinemia were relatively higher in older adults. Adjusted mean homocysteine concentrations were sharply decreased from the first to second decile of serum folate in males.
CONCLUSIONS
In the Korean population, the proportion of males who achieved desirable folate and homocysteine concentrations were lower than those of females. Although most Koreans have adequate vitamin B12, a suboptimal folate status is common, particularly among adolescents and young adults. These findings could establish a foundation for public health initiatives aimed at improving folate levels in the Korean population.; Summary

Korean summary
엽산과 비타민B12는 전 생애에 걸쳐 건강에 영향을 미치는 필수 비타민이다. 그러나 해당 비타민 상태에 대한 국내 자료는 부족한 실정이다. 본 연구는 국민건강영양조사 참여자로부터 수집된 혈청으로부터 엽산, 비타민B12, 그리고 이들의 기능성 지표인 호모시스테인 농도를 측정하였고 성별과 연령별 분포와 적합 상태를 평가하였다. 엽산 결핍과 고호모시스테인혈증은 남성에서 높은 유병률을 가졌다. 적정 엽산 상태를 충족하지 못하는 비율은 청소년과 젊은 성인에서 흔하게 관찰되었다. 대부분의 한국인은 충분한 비타민B12 수준을 가졌으나, 노인의 경우 정기적인 평가가 필요하다. 본 연구는 한국인이 최적의 엽산과 비타민B12 상태를 유지하기 위한 기반적 근거를 제공한다.

Key Message
Folate and vitamin B12 have significant health impacts throughout the life cycle. However, national-level data on B vitamins in Korea are limited. Serum folate, vitamin B12, and homocysteine concentrations were measured from samples stored during the national survey. In our study, the proportions of folate deficiency and hyperhomocysteinemia were higher in men than in women.Suboptimal folate status was common among adolescents and young adults. Most Koreans had adequate levels of vitamin B12; however, regular monitoring is warranted, especially in the older population. The current data provide a future direction for achieving optimal B vitamin status in the Korean population.

Regional disparities in the availability of cancer clinical trials in Korea: Jieun Jang, Wonyoung Choi, Sung Hoon Sim, Sokbom Kang; Epidemiol Health. 2024;46:e2024006. Published online December 11, 2023; DOI: https://doi.org/10.4178/epih.e2024006

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Abstract Summary PDF Supplementary Material: Abstract
OBJECTIVES
Unequal access to cancer clinical trials is an important issue, given the potential benefits of participation for cancer patients. We evaluated regional disparities in access to cancer clinical trials in Korea.
METHODS
From the Ministry of Food and Drug Safety database, we extracted 2,465 records of all cancer clinical trials approved between January 2012 and April 2023. To measure disparities in cancer clinical trial access, we calculated the ratio of clinical trials open to non-capital areas relative to those open to capital areas. We then analyzed temporal trends in this ratio, which we termed the trial geographical equity index (TGEI).
RESULTS
Disparities in access to cancer clinical trials, as indicated by the TGEI, did not significantly improve during the study period (regression coefficient, 0.002; p=0.59). However, for phase II/III trials sponsored by global pharmaceutical companies, the TGEI improved significantly (regression coefficient, 0.021; p<0.01). In contrast, the TGEI deteriorated for trials initiated by investigators or those testing domestically developed therapeutics (regression coefficient, -0.015; p=0.05). Furthermore, the increasing trend of TGEI for phase II/III trials sponsored by global companies began to reverse after 2019, coinciding with the outbreak of coronavirus disease 2019 (COVID-19).
CONCLUSIONS
Over the past decade, access to cancer clinical trials has improved in Korea, particularly for phase II/III trials evaluating therapeutics from global companies. However, this increase in accessibility has not extended to trials initiated by investigators or those assessing domestically developed therapeutics. Additionally, the impact of COVID-19 on disparities in clinical trial access should be closely monitored.; Summary

Korean summary
본 연구는 개시된 암 임상시험 수가 국내 수도권에 비해 비수도권에서 절대적으로 부족하고, 이러한 부족이 지난 10년간 개선되지 않았음을 보여줍니다. 다만, 글로벌 제약회사의 치료제를 검증하는 2상/3상 암 임상시험의 경우 임상시험 접근성에 대한 이러한 지역적 격차가 의미 있게 감소했으나 이러한 개선 또한 2019년 이후로는 정체되었을 수 있습니다. 상기 결과들은 임상시험 가용성의 형평성을 향상시키기 위해서는 국내 임상시험 개시 규모가 지역적 불균형을 이루고 있음에 대한 인식이 높아져야 하고, 비수도권 지역에서 임상시험 개시를 방해하는 장벽을 식별하는 데 추가적인 노력이 필요함을 강조합니다.

Key Message
The findings in this study indicate scarcity of cancer clinical trials in non-capital areas compared to that in capital areas of Korea, which has not improved over the past decade. However, this regional disparity in the access to clinical trials meaningfully decreased for phase II/III trials testing therapeutics from global pharmaceutical companies, though this progress may have stalled after 2019. This study highlights that increasing awareness of the regional imbalance in clinical trial access is vital and further efforts are needed to identify the barriers impeding the initiation of clinical trials in non-capital areas to improve the equity of availability.

The mediating role of atrial fibrillation in causal associations between risk factors and stroke: a Mendelian randomization study: Shanmei Qin, Mengmeng Wang, Dipender Gill, Zhizhong Zhang, Xinfeng Liu; Epidemiol Health. 2024;46:e2024005. Published online December 6, 2023; DOI: https://doi.org/10.4178/epih.e2024005

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Abstract Summary PDF Supplementary Material: Abstract
OBJECTIVES
Atrial fibrillation (AF) contributes to stroke development and progression. We aimed to quantify the mediating role of AF in the causal associations between a wide range of risk factors and stroke via a Mendelian randomization (MR) framework.
METHODS
We assessed the associations of 108 traits with stroke and its subtypes in a 2-sample univariable MR approach, then conducted a bidirectional MR analysis between these 108 traits and AF to evaluate the presence and direction of their causal associations. Finally, to further investigate the extent to which AF mediated the effects of eligible traits on stroke, we applied multivariable and 2-step MR techniques in a mediation analysis where outcomes were restricted to stroke types causally affected by AF (any stroke [AS], any ischemic stroke [AIS], and cardioembolic stroke [CES]).
RESULTS
Among 108 traits, 42 were putatively causal for at least 1 stroke type; of these 42 traits, 20 that had no bidirectional relationship with AF were retained. Finally, 33 associations of 15 eligible traits were examined in the mediation analysis. The mediation analyses for AS, AIS, and CES each included 11 eligible traits. After AF adjustment, the direct effects of all traits on CES were attenuated to null (all p>0.05), while the associations with AS and AIS persisted for most traits (AF-mediated proportion: from 6.6% [95% confidence interval, 2.7 to 0.6] to 52.0% [95% confidence interval, 39.8 to 64.3]).
CONCLUSIONS
The causal associations between all eligible traits and CES were largely mediated through AF, while most traits affected AS and AIS independently of AF.; Summary

Key Message
Previous studies have not systematically detected and quantified the mediating role of AF in causal associations between a wide range of risk factors and stroke types. This study, using several MR approaches, found that the causal associations between risk factors and stroke, and the role of AF in mediating these associations, varied across stroke types. Although AF largely mediated the trait-CES associations, most traits affected AS and AIS independently of AF, highlighting the need for accurate disease classification in clinical practice and trials.

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