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Lim GY, Chang Y, Kim I, Ryu S, Kwon R, Song J. Long working hours and increased risks of lean non-alcoholic fatty liver disease among Korean men and women. Sci Rep 2023; 13:12230. [PMID: 37507409 PMCID: PMC10382542 DOI: 10.1038/s41598-023-39154-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Accepted: 07/20/2023] [Indexed: 07/30/2023] Open
Abstract
Despite the increasing prevalence of lean nonalcoholic fatty liver disease (NAFLD), its risk factors are not well established. We examined the association between long working hours and incident NAFLD in lean Korean workers with emphasis on sex-based effect modification. This cohort study involved 46,113 non-overweight (BMI < 23 kg/m2) and NAFLD-free Korean workers (mean age, 35.5 years). Working hours were categorized into 35-40 (reference), 41-52, and ≥ 53 h. The presence of fatty liver and its severity were determined using ultrasonography and NAFLD fibrosis score (NFS), respectively. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using parametric proportional hazards models. Incident cases of 5901 lean NAFLD developed over a median follow-up of 3.8 years. The incidence of lean NAFLD increased with increasing working hours with a stronger association in men than in women (P for interaction < 0.001). For men, multivariable-adjusted HRs (95% CIs) for lean NAFLD in time-dependent models comparing working hours of 41-52 and ≥ 53 h compared to the reference category were 1.17 (1.07-1.28) and 1.25 (1.12-1.39), respectively. The excess relative risk of developing lean NAFLD with intermediate/high NFS was observed in working hours of 41-52 and ≥ 53 h with a corresponding HR of 1.66 (1.13-2.43) and 1.54 (0.94-2.51), respectively. Conversely, no significant associations were found between working hours and incidence of lean NAFLD in women. In conclusion, long working hours were significantly associated with an increased incidence of lean NAFLD and its severe form in men but not in women.
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Affiliation(s)
- Ga-Young Lim
- Center for Cohort Studies, Total Healthcare Center, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, 04514, Korea
- Institute of Medical Research, Sungkyunkwan University School of Medicine, Suwon, 16419, Korea
| | - Yoosoo Chang
- Center for Cohort Studies, Total Healthcare Center, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, 04514, Korea.
- Department of Occupational and Environmental Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Samsung Main Building B2, 250, Taepyung-Ro 2Ga, Jung-Gu, Seoul, 04514, Korea.
- Department of Clinical Research Design and Evaluation, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul, 06355, Korea.
| | - Inah Kim
- Hanyang University Graduate School of Public Health, Seoul, 04763, Korea
- Department of Occupational and Environmental Medicine, Hanyang University College of Medicine, Seoul, 04763, Korea
| | - Seungho Ryu
- Center for Cohort Studies, Total Healthcare Center, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, 04514, Korea
- Department of Occupational and Environmental Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Samsung Main Building B2, 250, Taepyung-Ro 2Ga, Jung-Gu, Seoul, 04514, Korea
- Department of Clinical Research Design and Evaluation, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul, 06355, Korea
| | - Ria Kwon
- Center for Cohort Studies, Total Healthcare Center, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, 04514, Korea
- Institute of Medical Research, Sungkyunkwan University School of Medicine, Suwon, 16419, Korea
| | - Jaechul Song
- Department of Occupational and Environmental Medicine, College of Medicine and Graduate School of Public Health, Hanyang University, 222 Wangshimni-Ro, Seoul, 04763, Korea.
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Le MH, Yeo YH, Li X, Li J, Zou B, Wu Y, Ye Q, Huang DQ, Zhao C, Zhang J, Liu C, Chang N, Xing F, Yan S, Wan ZH, Tang NSY, Mayumi M, Liu X, Liu C, Rui F, Yang H, Yang Y, Jin R, Le RHX, Xu Y, Le DM, Barnett S, Stave CD, Cheung R, Zhu Q, Nguyen MH. 2019 Global NAFLD Prevalence: A Systematic Review and Meta-analysis. Clin Gastroenterol Hepatol 2022; 20:2809-2817.e28. [PMID: 34890795 DOI: 10.1016/j.cgh.2021.12.002] [Citation(s) in RCA: 239] [Impact Index Per Article: 119.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 11/25/2021] [Accepted: 12/02/2021] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS The increasing rates of obesity and type 2 diabetes mellitus may lead to increased prevalence of nonalcoholic fatty liver disease (NAFLD). We aimed to determine the current and recent trends on the global and regional prevalence of NAFLD. METHODS Systematic search from inception to March 26, 2020 was performed without language restrictions. Two authors independently performed screening and data extraction. We performed meta-regression to determine trends in NAFLD prevalence. RESULTS We identified 17,244 articles from literature search and included 245 eligible studies involving 5,399,254 individuals. The pooled global prevalence of NAFLD was 29.8% (95% confidence interval [CI], 28.6%-31.1%); of these, 82.5% of included articles used ultrasound to diagnose NAFLD, with prevalence of 30.6% (95% CI, 29.2%-32.0%). South America (3 studies, 5716 individuals) and North America (4 studies, 18,236 individuals) had the highest NAFLD prevalence at 35.7% (95% CI, 34.0%-37.5%) and 35.3% (95% CI, 25.4%-45.9%), respectively. From 1991 to 2019, trend analysis showed NAFLD increased from 21.9% to 37.3% (yearly increase of 0.7%, P < .0001), with South America showing the most rapid change of 2.7% per year, followed by Europe at 1.1%. CONCLUSIONS Despite regional variation, the global prevalence of NAFLD is increasing overall. Policy makers must work toward reversing the current trends by increasing awareness of NAFLD and promoting healthy lifestyle environments.
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Affiliation(s)
- Michael H Le
- Division of Gastroenterology and Hepatology, Stanford University Medical Center, Palo Alto, California
| | - Yee Hui Yeo
- Division of Gastroenterology and Hepatology, Stanford University Medical Center, Palo Alto, California; Division of General Internal Medicine, Cedars-Sinai Medical Center, Los Angeles, California
| | - Xiaohe Li
- Division of Gastroenterology and Hepatology, Stanford University Medical Center, Palo Alto, California; Division of Infectious Disease, The Third People's Hospital of Shenzhen, Shenzhen, China
| | - Jie Li
- Department of Infectious Disease, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Ji'nan, Shandong, China
| | - Biyao Zou
- Division of Gastroenterology and Hepatology, Stanford University Medical Center, Palo Alto, California; Department of Epidemiology and Population Health, Stanford University School of Medicine, Stanford, California
| | - Yuankai Wu
- Division of Gastroenterology and Hepatology, Stanford University Medical Center, Palo Alto, California; Department of Infectious Diseases, the Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Qing Ye
- Division of Gastroenterology and Hepatology, Stanford University Medical Center, Palo Alto, California; The Third Central Clinical College of Tianjin Medical University, Tianjin; Department of Hepatology of The Third Central Hospital of Tianjin; Tianjin Key Laboratory of Artificial Cells, Tianjin, China
| | - Daniel Q Huang
- Department of Medicine, Yong Loo Lin School of Medicine and Division of Gastroenterology and Hepatology, Department of Medicine, National University Hospital, Singapore
| | - Changqing Zhao
- Department of Cirrhosis, Institute of Liver Disease, Shuguang Hospital, Shanghai University of T.C.M., Shanghai, China
| | - Jie Zhang
- Department of Gastroenterology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Ji'nan, Shandong, China
| | - Chenxi Liu
- Department of Gastroenterology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Ji'nan, Shandong, China
| | - Na Chang
- Department of Gastroenterology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Ji'nan, Shandong, China
| | - Feng Xing
- Department of Cirrhosis, Institute of Liver Disease, Shuguang Hospital, Shanghai University of T.C.M., Shanghai, China
| | - Shiping Yan
- Department of Gastroenterology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Ji'nan, Shandong, China
| | - Zi Hui Wan
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Natasha Sook Yee Tang
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Maeda Mayumi
- Division of Gastroenterology and Hepatology, Stanford University Medical Center, Palo Alto, California
| | - Xinting Liu
- Medical School of Chinese People's Liberation Army, Beijing, and Department of Pediatrics, the First Medical Center, Chinese People's Liberation Army General Hospital, Beijing, China
| | - Chuanli Liu
- Department of Infectious Disease, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Ji'nan, Shandong, China
| | - Fajuan Rui
- Department of Infectious Disease, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Ji'nan, Shandong, China
| | - Hongli Yang
- Department of Infectious Disease, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Ji'nan, Shandong, China
| | - Yao Yang
- Department of Gastroenterology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Ji'nan, Shandong, China
| | - Ruichun Jin
- Jining Medical University, Jining, Shandong, China
| | - Richard H X Le
- Division of Gastroenterology and Hepatology, Stanford University Medical Center, Palo Alto, California
| | - Yayun Xu
- Department of Infectious Disease, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Ji'nan, Shandong, China
| | - David M Le
- Division of Gastroenterology and Hepatology, Stanford University Medical Center, Palo Alto, California
| | - Scott Barnett
- Division of Gastroenterology and Hepatology, Stanford University Medical Center, Palo Alto, California
| | | | - Ramsey Cheung
- Division of Gastroenterology and Hepatology, Stanford University Medical Center, Palo Alto, California; Division of Gastroenterology and Hepatology, Veterans Affairs Palo Alto Health Care System, Palo Alto, California
| | - Qiang Zhu
- Department of Gastroenterology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Ji'nan, Shandong, China
| | - Mindie H Nguyen
- Division of Gastroenterology and Hepatology, Stanford University Medical Center, Palo Alto, California; Department of Epidemiology and Population Health, Stanford University School of Medicine, Stanford, California.
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Working Hours and Depressive and Anxiety Symptoms According to Shift Work and Gender. J Occup Environ Med 2022; 64:e316-e321. [DOI: 10.1097/jom.0000000000002515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Abstract
Shift work does not synchronize with the 24-hour human circadian rhythm, so shift workers experience various problems related to this disruption. This study investigated the relationship between suicidal risk and emotional difficulties such as depression and anxiety in shift workers according to gender. We analyzed data collected from 79,009 health checkup recipients. We checked psychosocial factors for different genders using the Chi-square test and t-tests. To examine the relationship between shift work and suicidal ideation, we estimated an odds ratio after adjustment for age, depression, and insomnia. There was no difference in terms of the risk of suicidal ideation between shift workers and day workers among women (adjusted odds ratio [AOR], 0.957; 95% confidence interval [CI], 0.826-1.109), whereas the risk of suicidal ideation was significantly higher for shift workers than for day workers among men (AOR, 1.157; 95% CI, 1.021-1.310). This study confirmed that associated factors of shift work-related suicidal ideation could act differently by gender. Shift work for women is generally associated with emotional difficulties such as depression and anxiety, whereas maladaptation to shift work may be related to suicidal ideation among men. A gender-specific suicide prevention approaches will be needed for shift workers.
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Mun E, Lee Y, Lee W, Park S. Cross-sectional association between long working hours and endoscopic gastritis: the Kangbuk Samsung Health Study. BMJ Open 2021; 11:e050037. [PMID: 34479937 PMCID: PMC8420663 DOI: 10.1136/bmjopen-2021-050037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
OBJECTIVES This study aimed to determine the cross-sectional association between long working hours and gastritis diagnosed by endoscopy. DESIGN Cross-sectional study. SETTING Large university hospitals in Seoul and Suwon, South Korea. PARTICIPANTS Workers in formal employment who underwent a comprehensive health examination at the Kangbuk Samsung Hospital Total Healthcare Centre clinics in Seoul and Suwon, South Korea, between January 2011 and December 2018. Of the 386 488 participants, 168 391 full-time day workers met the inclusion criteria and were included in the analysis. PRIMARY OUTCOME MEASURE Endoscopic gastritis. RESULTS The participants were predominantly college graduates or above (88.9%), male (71.2%) and in their 30s (51.1%), and the median age was 36 (IQR 31-42). Approximately 93.2% of participants had positive endoscopic gastritis, and there was a significant association between working hours and positive findings of endoscopic gastritis. The multivariate fully adjusted prevalence ratio (PR) of endoscopic gastritis for participants working >55 hours per week compared with 35-40 hours per week was 1.011 (95% CI 1.007 to 1.015). Furthermore, endoscopic findings were classified into nine subtypes of gastritis, including superficial gastritis, erosive gastritis, atrophic gastritis, intestinal metaplasia and haemorrhagic gastritis increased with longer working hours (p for trends <0.05). Their PRs for participants working >55 hours per week compared with 35-40 hours per week were 1.019 (95% CI 1.012 to 1.026), 1.025 (95% CI 1.011 to 1.040), 1.017 (95% CI 1.008 to 1.027), 1.066 (95% CI 1.028 to 1.105) and 1.177 (95% CI 1.007 to 1.375), respectively. CONCLUSIONS Working over 55 hours per week was cross-sectionally associated with positive findings of endoscopic gastritis. The study findings indicated potentially increased risks of superficial gastritis, erosive gastritis, atrophic gastritis, intestinal metaplasia and haemorrhagic gastritis among workers with long working hours (>55 hours per week), supporting the need for further exploration via longitudinal studies.
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Affiliation(s)
- Eunchan Mun
- Department of Occupational and Environmental Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Yesung Lee
- Department of Occupational and Environmental Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Woncheol Lee
- Department of Occupational and Environmental Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Soyoung Park
- Department of Occupational and Environmental Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
- Total Healthcare Center, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
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Long working hours are associated with a higher risk of non-alcoholic fatty liver disease: A large population-based Korean cohort study. PLoS One 2021; 16:e0255118. [PMID: 34297733 PMCID: PMC8301658 DOI: 10.1371/journal.pone.0255118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 07/09/2021] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Non-alcoholic fatty liver disease (NAFLD), a common chronic liver disease, may progress to fibrosis, cirrhosis, hepatocellular carcinoma, and liver failure. But only a few cross-sectional studies have reported an association of NAFLD with working hours. This cohort study further examined the association between working hours and the development of NAFLD. METHODS We included 79,048 Korean adults without NAFLD at baseline who underwent a comprehensive health examination and categorized weekly working hours into 35-40, 41-52, 53-60, and >60 hours. NAFLD was defined as the presence of fatty liver, in the absence of excessive alcohol use, as observed by ultrasound. RESULTS During a median follow-up of 6.6 years, 15,095 participants developed new-onset NAFLD (incidence rate, 5.55 per 100 person-years). After adjustment for confounders, the hazard ratios (95% confidence interval) for the development of NAFLD in 41-52, 53-60, and >60 working hours compared with that in 35-40 working hours were 1.07 (1.02-1.13), 1.06 (1.00-1.13), and 1.13 (1.05-1.23), respectively. Furthermore, the association remained significant after confounders were treated as time-varying covariates. CONCLUSION In this large-scale cohort, long working hours, especially >60 working hours a week, were independently associated with incident NAFLD. Our findings indicate that long working hours are a risk factor for NAFLD.
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Song E, Kim JA, Roh E, Yu JH, Kim NH, Yoo HJ, Seo JA, Kim SG, Kim NH, Baik SH, Choi KM. Long Working Hours and Risk of Nonalcoholic Fatty Liver Disease: Korea National Health and Nutrition Examination Survey VII. Front Endocrinol (Lausanne) 2021; 12:647459. [PMID: 34025577 PMCID: PMC8138556 DOI: 10.3389/fendo.2021.647459] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 04/19/2021] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND The global incidence of NAFLD is rising sharply due to various risk factors. As previous studies reported adverse health impact of long working hours on metabolic diseases, such as diabetes mellitus and obesity, it is plausible that NAFLD is also associated with working excessive hours. However, data regarding this issue is limited. METHODS In this cross-sectional study based on Korea National Health and Nutrition Examination Survey VII, 5,661 working adults without previous liver disease or heavy alcohol drinking habits were included. The subjects were categorized into three groups according to working hours: 36-42, 43-52, and 53-83 hours/week. NAFLD was defined using the hepatic steatosis index (HSI), which is a validated prediction model for determining NAFLD. RESULTS The prevalence of NAFLD (HSI ≥36) increased with longer working hours: 23.0%, 25.6%, and 30.6% in the 36-42, 43-52, and 53-83 hours/week group, respectively (p <0.001). Subjects who worked 53-83 hours/week had higher odds for NAFLD than those who worked the standard 36-42 hours/week (OR 1.23, 95% CI 1.02-1.50, p = 0.033) after adjusting for age, sex, body mass index, smoking, alcohol, exercise, diabetes mellitus, hypertension, serum triglyceride, and total cholesterol. This association was consistent across subgroups according to working schedule (daytime vs. shift workers) or occupation type (office vs. manual workers). In particular, the relationship between long working hours and NAFLD was pronounced in workers aged <60 years and in female workers. CONCLUSIONS Long working hours was significantly associated with NAFLD. Further prospective studies are required to validate this finding with causal relationship.
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Mun E, Lee W, Nam MW, Kim HI, Kim H, Lee Y, Park S. Cross-sectional association between long working hours and liver function: the Kangbuk Samsung Health Study. BMJ Open 2020; 10:e041595. [PMID: 33376174 PMCID: PMC7778760 DOI: 10.1136/bmjopen-2020-041595] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
OBJECTIVES Although the effects of long working hours on liver function remain unclear, in South Korea, there is a social perception that long working hours are associated with poor liver function. Thus, long working hours have recently become a major issue. This study aimed to determine the association between long working hours and liver function, as indicated by the alanine transaminase (ALT) levels. DESIGN Cross-sectional study. SETTING Large university hospitals in Seoul and Suwon, South Korea. PARTICIPANTS Workers in formal employment who underwent a comprehensive health examination at the Kangbuk Samsung Hospital Total Healthcare Centre clinics in Seoul and Suwon, South Korea, between January 2011 and December 2018. Of the 386 488 participants, 212 421 met the inclusion criteria and were included in the analysis. PRIMARY OUTCOME MEASURE ALT elevation. RESULTS The participants were predominantly well-educated (86.1%), male (69.3%) and in their 30s (49.6%). In total, 13.4% of the participants presented ALT elevation (>40 IU/L). There was no significant association between working hours and ALT elevation in the general population and in the hepatitis B surface antigen (HBsAg)-negative group. Conversely, in the HBsAg-positive group, working >60 hours per week compared with 35-40 hours per week was significantly associated with ALT elevation. The association was more pronounced in those with ALT levels >80 IU/L (OR 1.94, 95% CI 1.24 to 3.01) than in those with ALT levels >40 IU/L (OR: 1.45, 95% CI 1.20 to 1.75). The p values for trend were <0.05. CONCLUSIONS Long working hours were associated with ALT elevation only in hepatitis B virus carriers and not in the general population. Provided that there is adherence to the legal working hours, there is no need to further restrict working hours for liver health, irrespective of HBsAg status.
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Affiliation(s)
- Eunchan Mun
- Department of Occupational and Environmental Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Woncheol Lee
- Department of Occupational and Environmental Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Min-Woo Nam
- Department of Occupational and Environmental Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Hyun-Il Kim
- Department of Occupational and Environmental Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Hyeongcheol Kim
- Department of Occupational and Environmental Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Yesung Lee
- Department of Occupational and Environmental Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Soyoung Park
- Department of Occupational and Environmental Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
- Total Healthcare Center, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
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