Epidemiology and Health

Methods

Plan and operations of the 10th Korea National Health and Nutrition Examination Survey (2025–2027): Sun-Ja Kim, Sihyun Park, Sunja Kim, Suyeon Park, Yoonjung Kim, Yunjung Choi, Sungha Yun, Kyungwon Oh; Epidemiol Health. 2026;48:e2026001. Published online January 2, 2026; DOI: https://doi.org/10.4178/epih.e2026001

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Abstract Summary PDF Supplementary Material: Abstract
The Korea National Health and Nutrition Examination Survey (KNHANES) is a national health survey mandated by Article 16 of the National Health Promotion Act to assess the health and nutritional status of the Korean population. Over the past 2 decades, the survey has continuously introduced timely survey components while strengthening its survey methodology and operational systems to enhance both the policy relevance and scientific utility of its findings. The 10th KNHANES (2025–2027) preserves the statistical representativeness of its sampling design while expanding the use of web-based self-administered questionnaires to improve participant convenience. In response to Korea’s transition into a super-aged society, the 10th KNHANES incorporates enhanced older-adult health surveys, including osteoporosis assessment and older adults’ life functioning, and newly introduces items addressing social support as part of the social determinants of health. In addition, a longitudinal follow-up survey system has been established to monitor long-term changes in population health. Collectively, these changes are expected to improve understanding of aging-related health issues, support evidence-based national health policy development, and expand the applicability of KNHANES data for academic research.; Summary

Korean summary
국민건강영양조사는 국민건강증진법 제16조에 근거하여 1998년부터 우리 국민의 건강 및 영양 수준을 파악해 온 국가 단위 건강조사이다. 제10기(2025–2027) 국민건강영양조사는 통계적 대표성을 유지하면서 온라인 조사로의 지속적인 개선·확대, 초고령 사회 등 사회·보건환경 변화에 대응한 신규 조사항목 도입, 추적조사 체계 구축을 통해 국가 건강정책 및 만성질환 예방·관리 전략 수립을 위한 근거 생산을 강화하고자 한다.

Key Message
The Korea National Health and Nutrition Examination Survey (KNHANES) is a national health survey mandated by Article 16 of the National Health Promotion Act that has assessed the health and nutritional status of the Korean population since 1998. The 10th KNHANES (2025–2027) maintains statistical representativeness while further improving and expanding web-based self-administered surveys, incorporating new survey components in response to social and public health changes such as the transition to a super-aged society, and establishing a longitudinal follow-up system to strengthen the evidence base for national health policy development and chronic disease prevention and management.

Original Articles

Age-related trajectories of blood lipids and lipoproteins by sex, region, and waist circumference changes in Korea: a longitudinal cohort study: Mi Kyoung Son, Nam-Kyoo Lim, Joong-Yeon Lim, Hyun-Young Park; Epidemiol Health. 2025;47:e2025066. Published online December 9, 2025; DOI: https://doi.org/10.4178/epih.e2025066

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Abstract Summary PDF Supplementary Material: Abstract
OBJECTIVES
This study aimed to evaluate the longitudinal trajectories of lipid and lipoprotein levels with aging according to sex and changes in waist circumference (ΔWC) from midlife to late life.
METHODS
We included 4,345 male and 4,804 female participants aged 40-69 years at baseline from the Korean Genome and Epidemiology Study (2001-2018). The annual ΔWC was estimated using linear regression. Marginal models were fitted using mixed-effects regression.
RESULTS
The trajectories of total cholesterol (TC), non-high-density lipoprotein cholesterol (non-HDL-C), and low-density lipoprotein cholesterol (LDL-C) levels displayed an increasing trend until the 60s age range in females (approximately 10-15 mg/dL) and the late 40s in males (approximately 3-5 mg/dL), with a subsequent decline. In females, HDL-C levels increased until the early 50s, declined thereafter, and rose again from the 70s onward, with a more pronounced rise in urban than in rural areas, while remaining relatively stable in males. Triglyceride (TG) levels decreased with advancing age in males, whereas in females they increased up to the age of 70 years, followed by a decrease. Females exhibited greater increases in TC, non-HDL-C, HDL-C, LDL-C, and TG across all ages compared with males. Both males and females with a decrease in waist circumference (WC) during follow-up showed improvements in lipid and lipoprotein profiles relative to those with stable or increased WC.
CONCLUSIONS
Trends in lipid and lipoprotein levels vary according to age and sex, and a decrease in WC significantly improves lipid and lipoprotein profiles.; Summary

Korean summary
• 40세 이상 한국 성인을 대상으로 한 전향적 코호트에서 지질 및 지단백 궤적은 연령, 성별, 지역에 따라 상이한 양상을 보였으며, 총콜레스테롤, 저밀도 지단백 콜레스테롤, 비고밀도 지단백 콜레스테롤 수준은 농촌 지역에 비해 도시 지역에서 전반적으로 불리한 양상으로 나타났다. • 여성은 남성에 비해 5개 지질 및 지단백 지표 전반에서 더 큰 증가 폭을 보였으며, 여성의 고밀도 지단백 콜레스테롤은 폐경 이행기를 전후로 감소한 이후 다시 증가하였다. • 허리둘레의 지속적인 감소는 지질 및 지단백 프로파일의 개선과 관련되었으며, 이러한 결과는 복부비만 관리에 있어 연령과 성별을 고려한 맞춤형 접근의 중요성을 시사한다.

Key Message
• In a prospective cohort analysis of Korean adults aged 40 years and older, lipid and lipoprotein trajectories varied by age, sex, and region, with total cholesterol, low- density llipoprotein cholesterol, and non-high-density lipoprotein cholesterol levels generally showing less favorable patterns in urban than rural areas. • Females exhibited greater increases across all five lipid and lipoprotein measures than males, while high-density cholesterol levels in females declined around the menopausal transition and increased again in later life. • A sustained decrease in waist circumference was associated with improvements in lipid and lipoprotein profiles, highlighting the importance of age- and sex-specific approaches to abdominal obesity management.

Age-specific findings on lifestyle and trajectories of cognitive function from the Korean Longitudinal Study of Aging: Seungju lim, Eunyoung Yoo, Ickpyo Hong, Ji-Hyuk Park; Epidemiol Health. 2023;45:e2023098. Published online November 2, 2023; DOI: https://doi.org/10.4178/epih.e2023098

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Abstract Summary PDF

Abstract

OBJECTIVES
Few longitudinal studies have explored age-related differences in the relationship between lifestyle factors and cognitive decline. This study investigated lifestyle factors at baseline that slow the longitudinal rate of cognitive decline in young-old (55-64 years), middle-old (65-74 years), and old-old (75+ years) individuals.

METHODS

We conducted an 11-year follow-up that included 6,189 older adults from the Korean Longitudinal Study of Aging, which is a cohort study of community-dwelling older Koreans. Lifestyle factors, including physical activity, social activity (SA), smoking, and alcohol consumption were assessed at baseline. Cognitive function was measured at 2-year intervals over 11 years. Latent growth modeling and multi-group analysis were performed.

RESULTS

The influence of lifestyle factors on the rate of cognitive decline differed by age. Smoking at baseline (-0.05; 95% confidence interval [CI], -0.11 to -0.00, per study wave) accelerated cognitive decline in young-old individuals, whereas frequent participation in SA at baseline (0.02; 95% CI, 0.01 to 0.03, per study wave) decelerated cognitive decline in middle-old individuals. None of the lifestyle factors in this study decelerated cognitive decline in old-old individuals.

CONCLUSIONS

Cognitive strategies based on modifiable lifestyle factors such as smoking cessation in young-old individuals and frequent SA participation in middle-old age individuals may have great potential for preventing cognitive decline. Because the influence of lifestyle factors varied by age group, age-specific approaches are recommended to promote cognitive health.

Summary

Korean summary
본 연구는 국내 노인인구를 연령대별로 구분하여 연소노인(55-64세), 중고령노인(65-74세), 고령노인(75세+)의 인지저하 기울기를 가속 혹은 감속시키는 라이프스타일 요인을 파악하였다. '흡연'은 연소노인의 인지저하를 가속, '사회활동 참여 빈도'는 중고령노인의 인지저하를 감속시키는 것으로 나타났으며, 고령노인의 경우 유의미한 변수가 나타나지 않았다. 본 결과는 노인의 인지건강에 있어 연령대별 차별화된 라이프스타일 전략이 필요할 것을 시사한다.

Key Message
This study aimed to identify lifestyle factors that accelerate or decelerate the cognitive decline slope in the older population in South Korea, categorized by age groups: young-old adults (55-64), middle-old adults (65-74), and old-old adults (75+). The findings indicated that 'smoking' accelerates cognitive decline in young-old adults, while 'frequency of social activity participation' decelerates cognitive decline in middle-old adults. However, no significant lifestyle variables were identified for old-old adults. These results suggest the necessity of differentiated lifestyle strategies based on age groups for promoting cognitive health in the older population.

Citations

Citations to this article as recorded by

Predictive roles of oral and mental health among Korean older adults experiencing functional cognitive impairment: A secondary data analysis from the 2019 Community Health Survey
Kyungae Kim
Medicine.2026; 105(1): e46141. CrossRef
A rapid scoping review on operationalizing cognitive and social activities in research on dementia risk reduction
Jeroen Bruinsma, Ruud Roodbeen, Giselle G. A. Menting, Kay Deckers, Stevie Hendriks, Rik Crutzen
Aging & Mental Health.2025; 29(10): 1788. CrossRef
Genetic association of social participation with cognitive function: A bidirectional Mendelian randomization study
Aoqiang Zhai, Ruiqi Zou, Tianrun Lv, Siqi Yang, Yanjie Zhong, Yang Xiong, Fuyu Li, Haijie Hu
Journal of Alzheimer’s Disease.2025; 106(1): 259. CrossRef
The prevalence and the correlates of mental disorders among the elderly population: results from China Mental Health Survey
Jingjuan Pang, Minghui Li, Zhaorui Liu, Yueqin Huang, Xiaofei Hou, Guoli Yan, Xiangdong Xu, Limin Wang, Yongping Yan, Shuiyuan Xiao, Lingjiang Li, Jie Yan, Yaqin Yu, Xiufeng Xu, Zhizhong Wang, Yifeng Xu, Tao Li, Tingting Zhang, Huifang Yin, Guangming Xu
BMC Public Health.2025;[Epub] CrossRef
Social activities in multidomain dementia prevention interventions: insights from practice and a blueprint for the future
Jeroen Bruinsma, Leonie N. C. Visser, Alara Abaci, Anna Rosenberg, Ana Diaz, Sten Hanke, Rik Crutzen, Francesca Mangialasche, Miia Kivipelto, Charlotta Thunborg
Frontiers in Psychiatry.2024;[Epub] CrossRef
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Yue Chen, Xin Zheng, Yiming Wang, Chenan Liu, Jinyu Shi, Tong Liu, Shiqi Lin, Hailun Xie, Heyang Zhang, Xiaoyue Liu, Zhaoting Bu, Li Deng, Shouling Wu, Hanping Shi
Food & Function.2024; 15(15): 7837. CrossRef
Independent and Joint Associations of Socioeconomic Status and Lifestyle behaviors with Cognitive Impairment among Elderly Chinese Population
Y. Feng, S. Jia, W. Zhao, X. Wu, Y. Zuo, S. Wang, L. Zhao, M. Ma, X. Guo, C.S. Tarimo, Y. Miao, Jian Wu
The Journal of Prevention of Alzheimer's Disease.2024; 11(5): 1513. CrossRef

Long working hours and the risk of hypothyroidism in healthy Korean workers: a cohort study: Yesung Lee, Woncheol Lee, Hyoung-Ryoul Kim; Epidemiol Health. 2022;44:e2022104. Published online November 8, 2022; DOI: https://doi.org/10.4178/epih.e2022104

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Abstract Summary PDF Supplementary Material

Abstract

OBJECTIVES
Long working hours have been reported to cause various health problems, but are currently practiced in many countries. Building upon a previous cross-sectional study, the authors aimed to elucidate the causal relationship between long working hours and hypothyroidism through a longitudinal study.

METHODS

Data were collected at baseline from 45,259 participants without thyroid disease and with consistent weekly working hours (36-40, 41-52, 53-60, and >60 hours) during the follow-up period. Hypothyroidism was defined using the reference limits of serum thyroid-stimulating hormone and free thyroxine levels. By estimating hazard ratios (HRs) and 95% confidence intervals (CIs) using Cox proportional hazards regression analysis, the risk of incident hypothyroidism was evaluated with 36-40 hours of work per week as the reference.

RESULTS

During 138,261.7 person-years of follow-up, 2,914 participants developed hypothyroidism (incidence density, 2.11/102 person-years). The multivariable-adjusted HRs of incident hypothyroidism for 41-52 hours, 53-60 hours, and >60 hours of work per week were 1.13 (95% CI, 1.03 to 1.24), 2.53 (95% CI, 2.17 to 2.95), and 2.57 (95% CI, 2.09 to 3.15), respectively. In dose-response analyses, long working hours had an approximately linear relationship with hypothyroidism incidence. The risk of incident hypothyroidism in those who worked 53-60 hours and >60 hours per week compared with the reference group was significantly higher among the older age group (≥36 years, stratified by median age), men, and daytime workers.

CONCLUSIONS

This large-scale cohort study demonstrated the association between long working hours and an increased risk of incident hypothyroidism with a dose-response relationship.

Summary

Korean summary
대규모 코호트연구를 통해 장시간노동을 수행한 노동자들에서 갑상선기능저하증의 위험이 높아지는 것을 확인할 수 있었다. 특히 연령, 성, 교대근무 유무에 따라 층화하여 분석한 결과에서 고연령, 남성, 교대근무를 하지 않는 노동자에서 관련성의 크기가 증가하였다.

Key Message
This large-scale cohort study (The Kangbuk Samsung Health Study), which used 45,259 participants without thyroid disease at baseline and estimated hazard ratios (HRs) using Cox proportional hazards regression analysis, demonstrated the association between long working hours and an increased risk of incident hypothyroidism with a dose-response relationship especially in older age group, men, and daytime workers.

Citations

Citations to this article as recorded by

Effectiveness of Physical Activity-Led Workplace Health Promotion Interventions: A Systematic Review
Shichao Zhang, Mingjian Nie, Jiale Peng, Hong Ren
Healthcare.2025; 13(11): 1292. CrossRef
Association between shift work and the risk of hypothyroidism in adult male workers in Korea: a cohort study
Seonghyeon Kwon, Yesung Lee, Eunhye Seo, Daehoon Kim, Jaehong Lee, Youshik Jeong, Jihoon Kim, Jinsook Jeong, Woncheol Lee
Annals of Occupational and Environmental Medicine.2023;[Epub] CrossRef

Cohort Profile

Cohort profile: Singapore’s nationally representative Retirement and Health Study with 5 waves over 10 years: Reuben Ng, Yi Wen Tan, Kelvin Bryan Tan; Epidemiol Health. 2022;44:e2022030. Published online February 21, 2022; DOI: https://doi.org/10.4178/epih.e2022030

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6 Crossref

Abstract Summary PDF

Abstract

The Retirement and Health Study (RHS) is Singapore’s largest nationally representative cohort with over 15,000 participants (aged 45-85 years) followed across five timepoints in 10 years (2014-2024). Accounting for sample weights, the sample represents 1.2 million Singaporeans and permanent residents of a total population of 5.5 million. The RHS sought consent to link survey responses to relevant administrative data, enabling the cross-validation of self-reports with national databases. There are 10 sections in the RHS with over 400 questions, 50% of which are on respondents’ physical and mental health, healthcare utilization and insurance; the remaining 50% are about employment history, retirement adequacy, wealth, and household expenditure. The RHS was set up to provide microdata to compliment administrative data for whole-of-government policy making given that Singapore will reach super-aged status by 2026. Sample findings include a need for older adults to balance between immediate financial needs and investments regarding their pension funds. Also, 86% of older adults preferred to transit into partial retirement by reducing workloads. On the health front, existing studies utilising the RHS have revealed latent classes of disabilities, and that intentions to seek employment can mitigate disability developments. Another study reported that physical disability and social isolation was projected to increase, with ethnic disparities in social functioning. Overall, the RHS will be used for evidenced-informed policy agenda setting and evaluation across domains of health, finance, retirement adequacy, social and family development.

Summary

Key Message
The Retirement and Health Study (RHS) is Singapore’s largest nationally representative cohort with over 15,000 participants (aged 45-85 years) followed across five timepoints in 10 years (2014-2024). Sample findings include a need for older adults to balance between immediate financial needs and investments regarding their pension funds. Overall, the RHS will be used for evidenced-informed policy agenda setting and evaluation across domains of health, finance, retirement adequacy, social and family development.

Citations

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Childlessness and health in middle age and older adulthood: Evidence from Singapore
Christine Ho, Dahye Kim, Rohan Ray, Bussarawan Teerawichitchainan
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