Epidemiology and Health

Most-download articles are from the articles published in 2021 during the last three month.

Original Articles

Incidence of edentulism among older adults using the Korean National Health Insurance Service database, 2013-2018: Hyeonjeong Go, Eun-Kyong Kim, Hoi-In Jung, Song Vogue Ahn, Hosung Shin, Atsuo Amano, Youn-Hee Choi; Epidemiol Health. 2022;44:e2022091. Published online October 17, 2022; DOI: https://doi.org/10.4178/epih.e2022091

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Abstract PDF: Abstract
OBJECTIVES
Population aging is rapidly accelerating worldwide. Oral diseases related to aging are also on the rise. This study examined trends in the incidence of edentulism among the older Korean population using data from the Korean National Health Insurance Service (KNHIS).
METHODS
Data on older adults, aged ≥75 years of age, were obtained from the KNHIS for the period 2013-2018. Edentulism was defined as a treatment history of complete dentures in the KNHIS database. The exclusion criteria consisted of both disease codes and treatment codes related to conservative dental treatment, including periodontal and extraction treatment afterward. Crude incidence rates (CIRs) and age-standardized incidence rates (AIRs) with 95% confidence intervals were calculated and reported per 100,000 person-years by the direct method. Trends were tested by Cochrane Armitage models.
RESULTS
Statistically significant increasing trends in both CIRs and AIRs were found among the older Korean population registered in the KNHIS (CIRs, 707.92 to 895.92; AIRs, 705.11 to 889.68; p<0.01). The incidence tended to increase in both genders (p<0.01). Both CIRs and AIRs in specific regions also showed slight but significant annual increases except for Jeju Island (p<0.01 or <0.05). The incidence showed increasing trends (p<0.01) in all income quintiles apart from the highest quintile. The edentulism incidence was highest in the lowest income group (the first quintile).
CONCLUSIONS
Our data showed that the incidence of edentulism among the elderly showed an increasing trend from 2013 to 2018. This result provides a basis for future epidemiological studies on the incidence of edentulism in the older Korean population.; Summary

Korean summary

Key Message

No evidence of delay in colorectal cancer diagnosis during the COVID-19 pandemic in Gwangju and Jeonnam, Korea: Hye-Yeon Kim, Min-Gyeong Kim, Mi-Ran Kang, Jeong-Ho Yang, Min-Ho Shin, Sun-Seog Kweon; Epidemiol Health. 2022;44:e2022092. Published online October 17, 2022; DOI: https://doi.org/10.4178/epih.e2022092

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Abstract Summary PDF: Abstract
OBJECTIVES
We evaluated whether the coronavirus disease 2019 (COVID-19) pandemic caused delays in the diagnosis and treatment of colorectal cancer (CRC) in Korea, where there have been no regional or hospital lockdowns during the pandemic period.
METHODS
Data on CRC patients (n=1,445) diagnosed in Gwangju Metropolitan City and Jeonnam Province between January 2019 and December 2021 were assessed. The stage at the time of CRC diagnosis, route to diagnosis, time to initial cancer treatment, and length of hospital admission were compared before and during the COVID-19 pandemic. Logistic regression was also performed to identify factors associated with the risk for diagnosis in an advanced stage.
RESULTS
No negative effects indicating a higher CRC stage at diagnosis or delayed treatment during the pandemic were observed. Instead, the risk for an advanced stage at diagnosis (TNM stage III/IV) decreased in CRC patients diagnosed during the pandemic (odds ratio, 0.768; 95% confidence interval, 0.647 to 0.911). No significant differences in the interval from diagnosis to operation or chemotherapy were observed.
CONCLUSIONS
No negative effects on CRC diagnosis and treatment were found until the end of 2021, which may be related to the small magnitude of the COVID-19 epidemic, the absence of a lockdown policy in Korea, and the rebound in the number of diagnostic colonoscopy procedures in 2021.; Summary

Korean summary
COVID-19 판데믹 시기에 진단된 대장암환자에서 진단병기의 지연과 치료의 지연이 발생한 증거는 찾을 수 없었다. 이것은 2021년까지 한국에서는 유행규모가 크지 않았고, 의료기관 또는 지역단위의 봉쇄정책이 거의 없었기 때문일 것으로 추정된다.

Key Message
No evidence of delayed diagnosis and treatment of colorectal cancer was found during the COVID-19 pandemic period (2020-2021) in Gwangju-Jeonnam, Korea. It may be related to the small magnitude of the COVID-19 epidemic, the absence of a lockdown policy in Korea.

The associations of the national health and productivity management program with corporate profits in Japan: Yuichiro Yano, Hiroshi Kanegae, Koichi Node, Atsushi Mizuno, Akira Nishiyama, Hiromi Rakugi, Hiroshi Itoh, Kaori Kitaoka, Naoki Kashihara, Fumiaki Ikeno, Ichiro Tsuji, Kunio Okada; Epidemiol Health. 2022;44:e2022080. Published online September 23, 2022; DOI: https://doi.org/10.4178/epih.e2022080

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Abstract PDF: Abstract
OBJECTIVES
Using a dataset from a survey on national health and productivity management, we identified health and productivity factors associated with organizational profitability.
METHODS
The Ministry of Economy, Trade and Industry conducted an annual survey on Health and Productivity Management between 2014 and 2021. We assessed the associations of organizational health and productivity management using survey questions collected in 2017 and 2018, with the rate of change in profits from 2017 and 2018 to 2020. We identified factors associated with organizational profitability using eXtreme Gradient Boosting, and calculated SHapley Additive exPlanation (SHAP) values for each factor.
RESULTS
Among 1,593 companies (n= 4,359,834 employees), the mean age of employees at baseline was 40.3 years and the proportion of women was 25.8%. A confusion matrix for evaluating model performance had an accuracy of 0.997, precision of 0.993, recall of 0.997, and area under the precision-recall curve of 0.999. The most important factors related to an increase in corporate profits were the percentage of current smokers (SHAP value, 0.121), per-employee cost of health services (0.084) and medical services (0.050); the percentage of full-time employees working in sales departments (0.074) and distribution or customer service departments (0.054); the percentage of employees who slept well (0.055); and the percentage of employees within a company who regularly exercised (0.043).
CONCLUSIONS
Employees’ lifestyle-related health risk factors and organizations’ management systems were associated with organizational profitability. Lifestyle medicine professionals may demonstrate a significant return on investment by creating a healthier and more productive workforce.; Summary

Korean summary

Key Message

Mediation analysis of leisure activities on the association between cognitive function and mortality: a longitudinal study of 42,942 Chinese adults 65 years and older: Xingxing Chen, Wenfan Wu, Xian Zhang, Tingxi Long, Wenyu Zhu, Rundong Hu, Xurui Jin, Lijing L. Yan, Yao Yao; Epidemiol Health. 2022;44:e2022112. Published online November 27, 2022; DOI: https://doi.org/10.4178/epih.e2022112

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Abstract PDF: Abstract
study aimed to evaluate whether leisure activities causally mediate these associations.
METHODS
This longitudinal study included 42,246 participants aged over 65 years from the Chinese Longitudinal Healthy Longevity Survey. The Mini-Mental State Examination and a self-reported scale were used to measure cognitive status and leisure activities, respectively. We examined the associations of cognitive function and leisure activities with mortality using Cox proportional hazards models. Causal mediation analysis was used to assess whether leisure activities mediated the association between cognitive function and mortality.
RESULTS
Cognitive function and leisure activities were inversely associated with mortality. Leisure activities accounted for 28.3% (95% confidence interval [CI], 25.6 to 31.1) of the total effect of cognitive function and mortality. A higher mediated proportion (PM) was observed for physical leisure activities (PM, 20.1%; 95% CI, 18.0 to 22.3) than for social leisure activities (PM, 17.7%; 95% CI, 15.7 to 19.7). The mediating effect was higher among participants at younger ages (PM, 41.5%; 95% CI, 21.3 to 65.4), those with higher education levels (PM, 30.5%; 95% CI, 25.3 to 36.2), and residents of rural China (PM, 42.5%; 95% CI, 25.4 to 62.5).
CONCLUSIONS
Cognitive function was associated with inverse mortality. Leisure activities significantly mediated this association. Participation in leisure activities at the early stages of mild cognitive impairment could reduce the risk of mortality, which has a major impact on interventional strategies for healthy aging.; Summary

Korean summary

Key Message
Both cognitive function and leisure activities were associated with inverse mortality. Leisure activities were an important mediator of the association between cognitive function and mortality. A planned intervention for leisure activities, at an early stage of mild cognitive impairment, could promote health outcomes and optimally reduce the risk of mortality.

The association between tobacco or nicotine product use behaviors and non-compliance with mask-wearing during the COVID-19 pandemic: a cross-sectional study in Korea: Da-eun Lee, Heewon Kang, Sung-il Cho; Epidemiol Health. 2022;44:e2022087. Published online October 7, 2022; DOI: https://doi.org/10.4178/epih.e2022087

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Abstract Summary PDF Supplementary Material: Abstract
OBJECTIVES
It is necessary to investigate tobacco or nicotine product (TNP) use which acts as a risk factor for coronavirus disease 2019 (COVID-19) infection. Especially, wearing a mask is difficult to practice while using TNP. Therefore, this study aimed to examine the association between TNP use behaviors and non-compliance with mask-wearing during the COVID-19 pandemic.
METHODS
The samples of 208,618 Korean adults from 2020 Community Health Survey in Korea were used. As an independent variable, TNP use behaviors such as TNP use status, changes in TNP use after the COVID-19 outbreak, TNP types, and attempt to quit were analyzed. Logistic regression was performed on gender-stratified participants.
RESULTS
Among men, the odds ratio (OR) of current and former TNP users were 2.00 (95% confidence interval [CI], 1.66 to 2.40) and 1.32 (95% CI, 1.09 to 1.60), respectively, compared to never users. In women, OR was 1.50 (95% CI, 1.00 to 2.26) for former users. Cigarette use was more associated with not wearing a mask than non-cigarette tobacco or nicotine product (NCTNP) use (OR, 1.53; 95% CI, 1.12 to 2.08). Men whose TNP use decreased had lower non-compliance (OR, 0.52; 95% CI, 0.36 to 0.74); while women whose TNP use increased had lower non-compliance (OR, 0.13; 95% CI, 0.07 to 0.26).
CONCLUSIONS
Current and former users were less likely to wear masks. Cigarette use was more associated with not wearing a mask than NCTNP use. Changes in TNP use showed association for men and women; however, in the opposite direction. Therefore, more attention should be paid to TNP use prevention and cessation support during the epidemic of respiratory infectious diseases. Moreover, it is necessary to identify risk factors of cigarette users in compliance with mask-wearing.; Summary

Korean summary
담배 또는 니코틴 제품 (Tobacco or Nicotine Products, TNPs) 현재사용자와 과거사용자는 비사용자 대비 마스크 미착용 연관성이 높고, 비궐련 담배 또는 니코틴 제품 (Non-Cigarette Tobacco or Nicotine Products, NCTNPs) 사용자보다는 일반담배 사용자의 마스크 미착용 연관성이 높다. 남성에서는 코로나19 유행 이전 대비 TNPs 사용이 감소했을 때, 여성에서는 증가했을 때 마스크 미착용 연관성이 낮았다. 따라서 호흡기 감염병 유행 시기에는 더욱 TNPs 사용 예방과 금연 지원에 관심을 가질 것을 제안한다.

Key Message
During the epidemic of respiratory infectious diseases, more attention should be paid to tobacco or nicotine products (TNPs) use prevention and cessation support.

Brief Communication

Clinical severity according to the primary infection variant in patients with suspected SARS-CoV-2 reinfection in Korea: Myung-Jae Hwang, Insob Hwang, Chungmin Park, Hanul Park, Taejong Son, Jong-Hun Kim; Epidemiol Health. 2023;45:e2023007. Published online December 21, 2022; DOI: https://doi.org/10.4178/epih.e2023007

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Abstract PDF: Abstract
OBJECTIVES
We aimed to evaluate the severity of suspected severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reinfection according to variants of concern in Gyeongsangbuk-do and Daegu, Korea.
METHODS
The database of coronavirus disease 2019 (COVID-19) cases reported from epidemiological investigations through the integrated system operated by the Korea Disease Control and Prevention Agency, from January 20, 2020 to May 7, 2022 was combined with data from the Health Insurance Review and Assessment Service system. The severity odds ratio (SOR) in secondary infection episodes compared with primary infection was estimated using a generalized linear model with a binomial distribution.
RESULTS
In all patients, the SOR of SARS-CoV-2 reinfection was 0.89 (95% confidence interval [CI], 0.82 to 0.95), and the severity was lower than in the first infection. Patients who had been vaccinated within 91 days showed a more attenuated SOR (0.85; 95% CI, 0.74 to 0.98). However, despite vaccination, in patients with both primary and secondary infections caused by the Omicron variant, the severity was reduced to a lesser extent than in patients primarily infected with other variants.
CONCLUSIONS
We could make efforts to relieve the severity of COVID-19 in vulnerable populations, in which death is more likely, by recommending booster vaccinations in case of a resurgence.; Summary

Korean summary

Key Message

Original Articles

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: 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.

Association of the inflammatory balance of diet and lifestyle with colorectal cancer among Korean adults: a case-control study: Shinyoung Jun, Jeonghee Lee, Jae Hwan Oh, Hee Jin Chang, Dae Kyung Sohn, Aesun Shin, Jeongseon Kim; Epidemiol Health. 2022;44:e2022084. Published online September 30, 2022; DOI: https://doi.org/10.4178/epih.e2022084

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Abstract Summary PDF Supplementary Material: Abstract
OBJECTIVES
Dietary and lifestyle exposures may affect the risk of colorectal cancer (CRC) by promoting chronic inflammation. Therefore, we assessed the separate and joint associations of dietary and lifestyle inflammation scores (DIS and LIS, respectively) with CRC.
METHODS
Data from 919 pathologically confirmed CRC cases and 1,846 age- and sex-matched controls recruited at the National Cancer Center Korea were analyzed. We calculated the DIS and LIS, which characterize the collective contributions of 19 dietary and 4 lifestyle factors, respectively, to systemic inflammation by applying weights based on high-sensitivity C-reactive protein. A higher score represented a higher balance of pro- to anti-inflammatory exposures. Unconditional logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for CRC risk compared across the DIS and LIS tertile categories, with the lowest tertile as the reference group.
RESULTS
The highest DIS tertile had significantly increased odds of having CRC (OR, 2.65; 95% CI, 2.10 to 3.36), and the odds increased with increasing DIS. The highest LIS tertile group had 1.28-fold higher odds of having CRC (95% CI, 1.03 to 1.58). In the cross-classification analysis, the odds of having CRC increased as the DIS and LIS jointly increased until the DIS reached the highest tertile, where the risk was very high (3-fold or more) regardless of the LIS.
CONCLUSIONS
In conclusion, a higher balance of pro-inflammatory relative to anti-inflammatory dietary and lifestyle factors, especially dietary factors, was associated with higher CRC risk among Korean adults.; Summary

Korean summary
본 연구는 국립암센터에서 수집한 대장암 환자-대조군 데이터를 활용하여, 새롭게 개발된 식이 염증 지수(Dietary Inflammation Score, DIS) 및 생활습관 염증 지수(Lifestyle Inflammation Score, LIS)와 대장암 발생 위험 간의 연관성을 탐색하였다. 분석 결과, 식이 염증 지수 혹은 생활습관 염증 지수가 높은 집단에서 대장암 위험이 더 높아, 식이와 생활습관이 체내 염증 수준을 높여 대장암 발생 위험을 높일 가능성이 제기되었다

Key Message
Dietary inflammation score (DIS) and lifestyle inflammation score (LIS) quantify the collective effect of dietary and lifestyle factors, respectively, on systemic inflammation. In this case-control study, we assessed the associations of DIS and LIS with colorectal cancer risk among Korean adults. Our results suggest that a higher balance of pro-to anti-inflammatory dietary and lifestyle factors may be associated with higher risk for colorectal cancer. The findings from our study support that reducing inflammation through dietary or lifestyle changes could potentially reduce the risk for colorectal cancer.

COVID-19: Special Article

Changes in health behaviors and obesity of Korean adolescents before and during the COVID-19 pandemic: a special report using the Korea Youth Risk Behavior Survey: Chang-Mo Oh, Yangha Kim, Jieun Yang, Sunhye Choi, Kyungwon Oh; Epidemiol Health. 2023;45:e2023018. Published online February 14, 2023; DOI: https://doi.org/10.4178/epih.e2023018

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Abstract Summary PDF: Abstract
OBJECTIVES
This study aimed to investigate changes in health behaviors, including cigarette smoking, alcohol drinking, physical activity, dietary behaviors, and obesity, before and during the coronavirus disease 2019 (COVID-19) pandemic using the Korea Youth Risk Behavior Survey (KYRBS) database.
METHODS
KYRBS data from 2015 to 2021 were used in this study. Differences in health behaviors between before (pre-pandemic period: 2018-2019) and during (pandemic period: 2020-2021) the pandemic were examined. Differences were compared using linear regression and the chi-square test considering the complex survey design after adjusting for grade level.
RESULTS
The prevalence of current cigarette smoking and current alcohol drinking significantly decreased in both male and female students during the pandemic compared to the pre-pandemic period. However, the prevalence of obesity significantly increased in both male and female students during the same period. When examining physical activity and dietary behaviors closely related to obesity, fast food consumption increased and fruit consumption decreased during the pandemic in both male and female students, whereas no significant changes in physical activity were observed in either male or female students.
CONCLUSIONS
The deterioration of adolescent dietary behaviors and an increase in the prevalence of obesity can increase the future disease burden, and concerted efforts at the individual and national levels are needed to reduce obesity and promote healthy dietary behaviors.; Summary

Korean summary
이 연구는 한국 청소년건강행태조사자료(KYRBS)를 사용하여 코로나19 유행 전후의 우리나라 청소년들의 흡연, 음주, 신체활동, 식습관, 비만 등의 건강행태의 변화에 대하여 살펴보고자 하였다. 이 연구에서는 2015년부터 2021년까지의 청소년건강행태조사자료를 사용하여, 코로나19 유행 이전 (2018-2019년)과 코로나 유행 이후 (2020-2021년) 기간의 건강행태의 변화에 대하여 조사하였다. 학년레벨을 보정한 후, 복합표본설계를 고려하여 로지스틱 회귀분석과 카이제곱검정을 이용하여 코로나19 유행 이전 (2018-2019년)과 비교하여, 코로나 유행 이후 (2020-2021년) 기간의 건강행태의 변화가 있었는지에 대하여 확인하였다. 그 결과, 코로나19 유행 이전 (2018-2019년)과 비교하여, 코로나19 유행 기간(2020-2021년) 동안에 현재흡연율과 현재음주율이 유의하게 감소하였다. 그러나 동일한 기간 동안에 남학생과 여학생 모두에서 비만율이 유의하게 증가하였는데, 비만율과 관련된 신체활동 및 식습관에 대하여 살펴보았을 때, 신체활동에서는 유의한 변화가 없었던 반면, 남학생과 여학생 모두에서 패스트푸드 섭취는 증가하고 과일섭취가 감소한 것으로 나타났다. 따라서 코로나19 유행기간 동안 흡연율 및 음주율 등의 청소년 건강에 유익한 변화도 있었으나, 비만율도 같이 증가한 것을 확인할 수 있었다. 청소년기의 식습관의 악화 및 비만율의 증가는 미래 우리나라의 질병부담을 증가시킬 수 있기 때문에, 청소년의 비만율을 낮추고 건강한 식습관을 증진시키기 위한 개인 및 사회 차원의 노력이 필요하다.

Key Message
-The current cigarette smoking and current alcohol drinking rates significantly decreased among Korean adolescents during the pandemic period compared to the pre-pandemic period. -On the other hand, the obesity rate increased significantly especially among Korean male adolescents, which is accompanied by changes in dietary habits such as an increase in fast food intake and a decrease in fruit intake.

Original Articles

Maternal pre-pregnancy anemia and childhood anemia in Indonesia: a risk assessment using a population-based prospective longitudinal study: Fadila Wirawan, Dieta Nurrika; Epidemiol Health. 2022;44:e2022100. Published online November 1, 2022; DOI: https://doi.org/10.4178/epih.e2022100

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Abstract PDF: Abstract
OBJECTIVES
Anemia in children under 5 years of age is often overlooked despite its detrimental effects. The public health approach to anemia prevention includes the maternal pre-pregnancy phase. This study investigated the association between pre-pregnancy anemia and the risk of anemia in children under 5 years of age.
METHODS
This cohort study included non-pregnant women from the 2007 Indonesian Family Life Survey (IFLS) and their children under 5 in the 2014 IFLS. The anemia status of mothers and children was determined based on hemoglobin (Hb) levels using Hemocue. Mantel-Haenszel adjusted relative risks (aRRs), including risk stratification by covariates, were used for the final risk assessment.
RESULTS
In total, 637 children in the 2014 IFLS were included. The risk of having a child with anemia was 1.71-fold higher in women with pre-pregnancy anemia than in women without pre-pregnancy anemia (aRR, 1.71; 95% confidence interval [CI], 1.03 to 2.85). After risk stratification based on potential confounding variables, maternal pre-pregnancy anemia remained an independent risk factor for anemia in children who still breastfed at the time of data collection (relative risk [RR], 2.11; 95% CI, 1.16 to 3.86), in children who were given water earlier than 6 months of age (RR, 2.08; 95% CI, 1.20 to 3.61), in children of mothers with a normal or underweight pre-pregnancy body mass index (RR, 1.94; 95% CI, 1.20 to 3.14), and in children of mothers without current anemia (RR, 2.20; 95% CI, 1.21 to 3.99).
CONCLUSIONS
Pre-pregnancy anemia increased the risk of childhood anemia. A public health approach emphasizing pre-conception maternal health would enable better maternal and child morbidity risk prevention.; Summary

Korean summary

Key Message
Pre-pregnancy anemia increased the risk of childhood anemia by 1.7 times compared to without pre-pregnancy anemia, and increased when the child was still breastfed, given water before 6 months of age, and the mother had a normal or underweight pre-pregnancy BMI, regardless of the mother’s current no anemia status.

Inequitable distribution of excess mortality during the COVID-19 pandemic in Korea, 2020: Jin-Hwan Kim, Saerom Kim, Eunhye Park, Chang-yup Kim; Epidemiol Health. 2022;44:e2022081. Published online September 26, 2022; DOI: https://doi.org/10.4178/epih.e2022081

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Abstract PDF Supplementary Material: Abstract
OBJECTIVES
This study analyzed inequities in excess mortality according to region and socioeconomic position to explain the distribution of excess mortality in Korea in 2020.
METHODS
We acquired weekly all-cause mortality data from January 2015 to December 2020 from (1) the National Health Insurance Database and (2) Vital Statistics. Excess mortality for 2020 was calculated by comparing the weekly observed and expected deaths from the same period (2015-2019) using quasi-Poisson regression.
RESULTS
An inequitable distribution of excess mortality was identified. The estimated excess mortality in Korea was -29,112 (95% confidence interval, -29,832 to -28,391), corresponding to -55 per 100,000, and the ratio of observed deaths to expected deaths was 0.91. Negative excess mortality was observed except for females in the 0-14 age group. Male Medical Aid beneficiaries showed positive excess mortality, while non-disabled and disabled groups showed similar negative values. When the standardized mortality ratio was calculated for the top 10 causes of death, deaths from Alzheimer’s disease and septicemia increased, whereas those from diabetes mellitus and cerebrovascular disease decreased. The decrease in mortality was primarily concentrated in older adults, while the mortality of young females increased due to increased intentional self-harm.
CONCLUSIONS
This study adds essential evidence regarding the overall performance of Korea. The observed inequalities according to various socioeconomic variables indicate that the results of strict measures to control coronavirus disease 2019 were not distributed equitably. Efforts should be made to properly evaluate the current and future problems related to the pandemic.; Summary

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Key Message

The risk of gastric cancer according to changes in smoking status among Korean men: Sung Keun Park, Min-Ho Kim, Chang-Mo Oh, Eunhee Ha, Eun Hye Yang, Woo Yeon Hwang, Ann Hee You, Jae-Hong Ryoo; Epidemiol Health. 2022;44:e2022086. Published online October 7, 2022; DOI: https://doi.org/10.4178/epih.e2022086

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Abstract Summary PDF: Abstract
OBJECTIVES
Smoking is a risk factor for gastric cancer. Studies have shown that the risk of gastric cancer can vary by smoking status and smoking amount at a single point in time. However, few data have been reported about the effect of changes in smoking status over time on the risk of gastric cancer.
METHODS
This study collected data from the National Health Insurance Corporation in Korea on 97,700 Korean men without gastric cancer who underwent health check-ups from 2002 to 2013. The smoking status (never smoked, quit smoking, and currently smoking) of study participants was assessed in 2003-2004 and 2009, and the results were categorized into 7 groups: never-never, never-quit, never-current, quit-quit, quit-current, current-quit, and current-current. Participants were followed until 2013 to identify incident gastric cancer. A multivariate Cox proportional hazard model was used to calculate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for incident gastric cancer according to changes in smoking status and smoking amount (pack-years).
RESULTS
Compared with group 1 (never-never), participants currently smoking in 2009 (never-current, quit-current, and current-current) had higher HRs for gastric cancer (never-quit: 1.077; 95% CI, 0.887 to 1.306, never-current: 1.347; 95% CI, 0.983 to1.846, quit-quit: 1.086; 95% CI, 0.863 to 1.366, quit-current: 1.538; 95% CI, 1.042 to 2.269, current-quit: 1.339; 95% CI, 1.077 to 1.666, and current-current: 1.589; 95% CI, 1.355 to 1.864, respectively). The risk for gastric cancer was highest in heavy smokers, followed by moderate smokers.
CONCLUSIONS
In all categories of smoking status, current smoking was associated with the highest risk of gastric cancer. Heavy smoking was associated with an increased risk of gastric cancer, even in former smokers.; Summary

Korean summary
현재 흡연자의 경우 과거 흡연여부와 관계 없이 위암의 위험성이 가장 증가한다. 과거 흡연자의 경우에는 흡연량이 많은 경우에는 위암의 위험성이 증가한다. 이런 결과는 금연이나 흡연량을 줄이는 것이 위암의 위험성을 감소시키는데 매우 중요한 요인이란 것을 확인할 수 있다.

Key Message
Current smoking was associated with an increased risk of gastric cancer, regardless of previous smoking status. Although former smoking was not associated with an increased risk of gastric cancer, former smokers with a history of heavy smoking had an increased risk of gastric cancer. These results suggest that smoking cessation and reducing smoking amounts are both important factors in reducing the risk of gastric cancer.

Age at first childbirth and the risk of hypertriglyceridemia among Korean women: Hye Rin Choi, Hyeon Chang Kim; Epidemiol Health. 2023;45:e2023010. Published online December 29, 2022; DOI: https://doi.org/10.4178/epih.e2023010

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Abstract Summary PDF: Abstract
OBJECTIVES
We aimed to investigate the association of age at first childbirth with the risk of hypertriglyceridemia among Korean women.
METHODS
This study used data from the Korean Genome and Epidemiology Study–Cardiovascular Disease Association Study. In total, 16,747 women were included in the cross-sectional analysis, and 6,250 women were included in the longitudinal analysis. The participants were divided based on their age at first childbirth (<20, 20-24, 25-29, and ≥30 years). Hypertriglyceridemia was defined as triglyceride levels of ≥150 mg/dL.
RESULTS
The multivariable-adjusted odds ratio for prevalent hypertriglyceridemia was 1.19 (95% confidence interval [CI], 1.01 to 1.40) in women whose first childbirth was before 20 years of age, compared to those whose first childbirth was at 25-29 years of age, after adjustment for age, study site, body mass index, blood pressure, diabetes, alcohol consumption, carbohydrate intake, income, marital status, education, parity, usage of oral contraceptives, and hormone replacement status. During a median follow-up of 5.2 years, 1,770 women developed hypertriglyceridemia. Compared with women who gave birth to their first child between 25 years and 29 years of age, those giving birth to their first child before 20 years of age had a higher risk for incident hypertriglyceridemia in later life (adjusted hazard ratio, 1.25; 95% CI, 0.99 to 1.57).
CONCLUSIONS
Giving birth to one’s first child before the age of 20 years was associated with an increased risk of hypertriglyceridemia among Korean women.; Summary

Korean summary
한국인유전체역학조사사업의 농촌기반 코호트 자료를 분석한 결과, 20세 이전에 초산을 경험한 한국 여성에서 25-29세에 경험한 군에 비해 고중성지방혈증에 걸릴 위험이 증가하였음 폐경 후 여성을 한정하여 보았을 때도 20세 이전 초산과 고중성지방혈증 간의 유의한 관련성을 보였음 여성의 출산 등 여성력이 심혈관계 질환 발생의 위험요인으로 작용할 수 있으며, 출산력에 따른 혈중 중성지방수치 관리 전략 마련이 필요함

Key Message
Among Korean women, having their first child before the age of 20 was associated with an increased risk of hypertriglyceridemia. Targeted preventive actions should be developed for those women who give birth at an early age in order to manage their blood triglyceride levels.

Methods

Meta-analysis of diagnostic test accuracy studies with multiple thresholds for data integration: Sung Ryul Shim; Epidemiol Health. 2022;44:e2022083. Published online September 28, 2022; DOI: https://doi.org/10.4178/epih.e2022083

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Abstract Summary PDF Supplementary Material: Abstract
OBJECTIVES
The objective of this study is to introduce methods to use all of the information without omission when individual studies provide multiple effect sizes according to multiple cut-off values (thresholds) during diagnostic test accuracy (DTA) for data integration. For diagnostic test meta-analysis, a general performance method for synthesizing data according to one cut value in one study and a performance method for synthesizing data according to two or more cut values in one study were compared and analyzed.
METHODS
As sample data for meta-analysis of DTA studies, 13 DTA studies on prostate cancer (34 effect sizes including total cut-offs) were collected. The summary statistics were calculated and the summary line was analyzed using the “meta”, “mada”, and “diagmeta” packagesof the R software.
RESULTS
The summary statistics of the random effect model univariate analysis of the “meta” package with a single cut-off corresponding to the highest Youden index in a single study and those of the bivariate analysis of the “mada” package were highly similar. However, in the bivariate analysis of the “diagmeta” package including all cut-off values, the sensitivity decreased and the specificity increased as the amount of data increased.
CONCLUSIONS
Considering the heterogeneity of the summary receiver op erating characteristic curve and the use of all given cut-offs, the use of the bivariate analysis model of the “diagmeta” package is recommended. This study focused on practical methods of DTA rather than theoretical concepts for use by researchers whose fields of study are non-statistics related. By performing this study, we hope that many researchers will use R software to determine the DTA more easily, and that there will be greater interest in related research.; Summary

Korean summary
본 연구는 진단검사 메타분석시 개별 대상연구가 다수의 기준치 (cut-off value, threshold)에 따른 여러 개의 효과크기를 제공하고 있을 때, 정보의 누락없이 이를 모두 사용하는 방법과 더불어 기존의 수행방법도 비교 분석하였기에 연구에 적합한 모델 선택에 도움이 될 것이다.

Key Message
The objective of this study is to introduce methods to use all of the information without omission when indi¬vidual studies provide multiple effect sizes according to multiple cut-off values (thresholds) during diagnostic test accuracy (DTA) for data integration.

Original Article

Effect of mammography screening on the long-term survival of breast cancer patients: results from the National Cancer Screening Program in Korea: Xuan Quy Luu, Kyeongmin Lee, Jae Kwan Jun, Mina Suh, Kyu-Won Jung, Kui Son Choi; Epidemiol Health. 2022;44:e2022094. Published online October 26, 2022; DOI: https://doi.org/10.4178/epih.e2022094

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Abstract PDF Supplementary Material: Abstract
OBJECTIVES
This study investigated the effect of mammography screening on the long-term survival of breast cancer (BC) patients aged 40 years or older according to their screening history and duration since screening.
METHODS
The study cohort was organized from 3 nationwide databases of the Korean National Cancer Screening Program, the Korean Central Cancer Registry, and death certificates. We included 24,387 women diagnosed with invasive BC or ductal carcinoma in situ in 2008 and 2009 and followed up until December 31, 2019. Cox proportional-hazards regression was used to investigate the effect of BC screening on the risk of death.
RESULTS
Overall, 20,916 of 24,387 patients (85.8%) were alive at the end of the follow-up period (median: 10.5 years). The long-term survival rate was significantly lower in the never-screened group (80.3%) than in the screened group (88.9%) (p<0.001). A 35% reduction in the risk of BC death (hazard ratio [HR], 0.65; 95% confidence interval [CI], 0.60 to 0.70) from screening was observed. A subgroup analysis according to the cancer stage showed 62%, 36%, and 24% lower risks of BC death for the localized stage, regional stage, and distant stage, respectively. Women aged 40-49 years received the least benefit from BC screening (HR, 0.71; 95% CI, 0.62 to 0.81).
CONCLUSIONS
Mammography screening was effective in reducing the risk of BC-specific death in Asian women across all cancer stages. However, this effect was relatively small among women in their 40s, suggesting that more detailed and specialized screening strategies are needed for that age group.; Summary

Korean summary

Key Message

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