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Objective Rheumatoid arthritis (RA) and chronic obstructive pulmonary disease (COPD) are both chronic inflammatory diseases; the prevalence of COPD in RA patients is known to be high. However, the prevalence of both RA and COPD differs according to sex; the relationship between RA and COPD may also vary according to sex. Therefore, we investigated the prevalence of COPD and its association in patients with RA in Korea by sex. Methods We conducted a nationwide cross-sectional study using data from the Korea National Health and Nutrition Examination Survey. A total of 12 417 men and 15 878 women were included. In this study, RA was defined as physician diagnosed or currently under RA treatment. COPD was defined based on spirometry results, chronic symptoms, and smoking history. Multivariable logistic regression models were employed and we calculated the odds ratios (ORs) and 95% confidence intervals (CIs) for COPD prevalence in patients with RA. Results The prevalence of COPD was 15.5% in men with RA, 3.5% in women with RA, 7.8% in men without RA, and 2.2% in women without RA. After adjustment for potential confounding variables, including smoking status, RA was significantly associated with COPD in men (OR 2.16, 95% CI 1.06-4.40), but not in women (OR 1.58, 95% CI 0.81-3.10). Conclusions In Korea, the prevalence of COPD was high in patients with RA of both sexes; RA and COPD was significantly likely to be associated in men, but not in women.

This cross-sectional study investigated the association between long working hours and prevalence of poor self-rated health (SRH) in Korean young workers using data from the 6th Korea Youth Panel Survey 2007. A total of 3317 young wage workers were included. Weekly working hours were divided into four groups (36 to 40 hours, 41 to 52 hours, 53 to 60 hours, and more than 60 hours per week). Multiple logistic regression was performed to investigate the association between long working hours and SRH, adjusting for demographic and work-related factors. Long working hours were associated with increased risk of poor SRH, in both the men and women. Legal restriction on working hours should be suitably applied to help improve the health status of Korean young workers.

Objectives: This study aimed to investigate the association between occupational clusters and allergic rhinitis (AR). Methods: The study was based on data from the Korean National Health and Nutrition Examination Survey (KNHANES: 2007-2015). This study included 46,965 individuals: 20,491 men and 26,474 women. AR was defined as having been diagnosed by a physician. Occupations were classified according to occupational characteristics and skill levels into white (chief executives, senior officials, legislators, managers, professionals, and technicians), pink (clerks, clerical support workers, services and sales workers), blue (craft and related trades workers, drivers, plant and machine operators, assemblers, elementary occupation workers), and green (skilled agricultural, forestry, and fishery workers) categories. We calculated the odds ratios (ORs) and 95% confidence intervals (CIs) of AR according to the occupational clusters by using the chi-squared test and logistic regression. Results: In the study population, 10.7% of the men and 13.5% of the women had AR. The prevalence of AR was highest among white-collar workers, followed by pink, blue, and green-collar workers. Compared to green-collar workers, among men the adjusted ORs of the blue, pink, and white-collar workers were 2.00 (95% CI 1.58-2.53), 2.46 (95% CI 1.91-3.15), and 2.78 (95% CI 2.20-3.51), respectively; and among women were 2.45 (95% CI 1.99-3.02), 2.64 (95% CI 2.15-3.25), and 3.63 (95% CI 2.96-4.47), respectively. Conclusions: This study suggests that AR prevalence is significantly associated with occupational clusters.

Long working hours are known to have a negative effect on health. However, there is no clear evidence for a direct link between mental health and long working hours in the young adult populations. Therefore, we aimed to determine whether long working hours are associated with mental health in young adult workers. Data were collected from a 2012 follow-up survey of the Youth Panel 2007. A total of 3,332 young adult employees (aged 20 to 35) were enrolled in the study. We analyzed stress, depression, and suicidal thoughts by multivariate logistic regression analysis based on working hours (41 to 50, 51 to 60 and over 60 hours, compared to 31 to 40 hours per week), which was adjusted for sex, age, marriage status, region, and educational level. From the 3,332 young adult employees, about 60% of the workers worked more than 40 hours and 17% of the workers worked more than 50 hours per week. In a Chi-square test, stress level, depression, and suicidal thoughts increased with increasing working hours (p-value

Introduction In juvenile idiopathic arthritis (JIA), interleukin (IL)-1, IL-6, and tumor necrosis factor-alpha (TNF-α) are associated with development and progression of JIA. We investigated whether IL-1, IL-6, and TNF-α polymorphisms were associated with susceptibility to JIA. Evidence acquisition A meta-analysis was conducted on the associations between IL-1α- 899 C/T, IL-1β-511 C/T, IL-6-174 G/C, and TNF-α-308 G/A and -238 G/A polymorphisms, and JIA (PubMed and Embase). Evidence synthesis A total of 27 studies involving 4,678 JIA patients and 7,634 controls were considered in the meta-analysis. There was no association between the IL-1α-899 C/T, IL-1β- 511 C/T, IL-6-174 G/C, and TNF-α-308 G/A and -238 G/A polymorphisms, and JIA in allele contrast or any other genetic models. In subgroup analysis based on subtype, except for the dominant model of TNF-α-238 G/A, systemic JIA was not significantly associated with IL-6 and TNF-α polymorphisms. In Caucasians, the dominant and additive models of IL-1β-511 C/T were significantly associated with JIA (odds ratio [OR] 1.48, 95% confidence interval [CI] 1.09-2.00, P =0.01; OR 1.46, 95% CI 1.05-2.03, P =0.02, respectively). Conclusions This meta-analysis showed no association between IL-1, IL-6, and TNF-α polymorphisms, and JIA, but the TT genotype of IL-1β -511 C/T was associated with higher prevalence of JIA in Caucasians.

OBJECTIVE Coffee is one of the world's most consumed beverages, and its consumption is increasing. Serum uric acid levels are affected by dietary factors, and increased levels can cause a variety of diseases, including gout. This study aimed to investigate the relationship between coffee consumption and serum uric acid levels in the general Korean population. METHODS A nationwide cross-sectional study was conducted using data from the Korean National Health and Nutrition Examination Survey in 2016. A total of 3005 participants who checked serum uric acid levels and a completed coffee consumption survey were included (1146 men and 1859 women). The amount of coffee consumption was examined via self-reporting and categorized as none

Background: Rheumatoid arthritis (RA) is known to be associated with coronary artery diseases (CAD). Previous studies of the association between RA and CAD were reported mainly in non-Asian groups. We aimed to examine the prevalence of RA and the relationship between RA and CAD in South Korea. Methods: We conducted a nationwide cross-sectional study by using the Korea National Health and Nutrition Examination Survey, which collected data for four years between 2008 and 2012. A total of 25,828 eligible participants were included. To balance the distribution of baseline characteristics, we used propensity scorematching. A multivariable logistic regression model was employed and we calculated the odds ratios (ORs) and 95% confidence intervals (CI) for the odds of the participants with RA on CAD prevalence. Results: The prevalence of RA in Korea from 2008 to 2012 was 0.6% and RA was predominant among elderly women. The prevalence of CAD in patients with RA was significantly higher than in general population. After propensity score-matching to balance the confounding factors, RA was significantly associated with CAD (OR 2.97, 95% CI 1.15-7.68, P= 0.02). Conclusions: The prevalence of RA in South Korea was comparable to the worldwide data, and the presence of CAD in RA patients was more than two-fold.

Objectives: We aimed to investigate the health inequity of victims of occupational accidents through the association between socioeconomic status and unmet healthcare need. Methods: Data from the first and second Panel Study of Workers' Compensation Insurance were used, which included 1,803 participants. The odds ratio and 95% confidence intervals for the unmet healthcare needs of participants with a lower socioeconomic status and other socioeconomic statuses were investigated using multivariate regression analysis. Results: Among all participants, 103 had unmet healthcare needs, whereas 1,700 did not. After adjusting for sex, age, smoking, alcohol, chronic disease, recuperation duration, accident type, disability, and economic participation, the odds ratio of unmet healthcare needs in participants with a lower socioeconomic status was 2.04 (95% confidence interval 1.32-3.15) compared to participants with other socioeconomic statuses. Conclusions: The victims of occupational accidents who have a lower socioeconomic status are more likely to have unmet healthcare needs in comparison to those with other socioeconomic statuses.

Background Occupation influences the risk for developing chronic metabolic diseases. Methods We compared the prevalence of MetS by International Standard Classification of Occupations using the nationally representative data in Korea (KNHANES). We enrolled 16,763 workers (9,175 males; 7,588 females) who had measurements for the National Cholesterol Education Program criteria III and other variables. OR and 95%CIs for MetS and its components were estimated according to occupation using the multiple logistic regression models. Results The occupational groups with the highest age-standardized prevalence of MetS were lower skilled white-collar men (31.1 ± 2.4%) and green-collar women (24.2 ± 2.9%). Compared with the unskilled male blue-collar group, which had the lowest prevalence of MetS, the OR (95%CIs) of MetS in men were 1.77 (1.45–2.15) in higher skilled white-collar, 1.82 (1.47–2.26) in lower-skilled white-collar, 1.63 (1.32–2.01) in pink-collar and 1.37 (1.13–1.66) in skilled blue-collar workers in final logistic regression model. Conclusions MetS and its components vary by occupational category and gender in ways that may guide health interventions. Am. J. Ind. Med. © 2016 Wiley Periodicals, Inc.

Objectives Low-level lead exposure has been associated with increases in blood pressure (BP) and impairment of the cardiovascular system. Prehypertension is not categorized as a disease currently; however, individuals with untreated prehypertension are known to be at increased risk of progression to hypertension and mortality caused by cardiovascular disease. We investigated the association between blood lead levels below the threshold for the harmful effects of lead and the prevalence of prehypertension in Korean adults. Methods A total of 8,493 participants (3,945 men and 4,548 women) were included in the current analysis, using data from the fourth, fifth, and sixth Korean National Health and Nutrition Examination Survey (KNHANES) in 2007–2013. Blood analysis, self-report questionnaires, and physical examinations were used to assess blood lead levels, BP, and medical history. Odds ratios (OR) and 95% confidence intervals (95% CI) for prehypertension were calculated using multiple logistic regression models. Results Compared to the first quartile (Q1) blood lead level (0.206–1.539 μg/dl), the ORs (95% CI) were 1.24 (1.04–1.48) in Q2, (1.540–2.056 μg/dl), 1.27 (1.06–1.52) in Q3, (2.057–2.716 μg/dl), and 1.30 (1.07–1.60) in Q4 (2.717–24.532 μg/dl) for the prevalence of prehypertension after adjusting for age, sex, morbidity status, socioeconomic status, and health behavioral variables. Conclusions Our large, cross-sectional, nationwide study revealed that blood lead levels below the threshold for the harmful effects of lead were significantly associated with prehypertension. Am. J. Hum. Biol., 2016. © 2016 Wiley Periodicals, Inc.

We aimed to examine whether there is a correlation between the health recovery of industrial accident victims and their perceived socioeconomic status. Data were obtained from the first Panel Study of Worker's Compensation Insurance, which included 2,000 participants. We performed multivariate regression analysis and determined the odds ratios for participants with a subjectively lower socioeconomic status and for those with a subjectively lower middle socioeconomic status using 95% confidence intervals. An additional multivariate regression analysis yielded the odds ratios for participants with a subjectively lower socioeconomic status and those with a subjectively upper middle socioeconomic class using 95% confidence intervals. Of all participants, 299 reported a full recovery, whereas 1,701 did not. We examined the odds ratio (95% confidence intervals) for participants' health recovery according to their subjective socioeconomic status while controlling for sex, age, education, tobacco use, alcohol use, subjective state of health prior to the accident, chronic disease, employment duration, recovery period, accident type, disability status, disability rating, and economic participation. The odds of recovery in participants with a subjectively lower middle socioeconomic status were 1.707 times greater (1.264-2.305) than that of those with a subjectively lower socioeconomic status. Similarly, the odds of recovery in participants with a subjectively upper middle socioeconomic status were 3.124 times greater (1.795-5.438) than that of those with a subjectively lower socioeconomic status. Our findings indicate that participants' perceived socioeconomic disparities extend to disparities in their health status. The reinforcement of welfare measures is greatly needed to temper these disparities., Graphical Abstract

Workplace violence is related to various health effects including mental illness such as anxiety or depression. In this study, the relationship between the experience of workplace violence and depression in substitute drivers in Korea, namely, daeri drivers, was investigated. To assess workplace violence, questions regarding types and frequency of the experience of violence over the past year were asked to the daeri drivers. In order to assess the risk of depression, the Center for Epidemiological Studies Depression Scale was used. Odds ratios with 95% confidence intervals of depression were estimated using multiple logistic regression analysis. All of the daeri drivers had experienced instance of verbal violence while driving and 66 of the drivers (34.1%) had been in such a situation more than once in the past quarter of a year. Sixty-eight daeri drivers (42.2%) had experienced certain type of physical violence over the past year. Compared to daeri drivers who had experienced workplace verbal violence less than 4 times and who had not experienced workplace physical violence over the past year, higher odds ratio was observed in daeri drivers who had experienced workplace verbal violence or physical violence, more than 4 times and more than one time respectively, after adjustment. Experience of verbal or physical type of workplace violence over the past year increased the risk of depression in the daeri drivers. Because violence against drivers can compromise the safety of the driver, the customer, and all the passengers, it is imperative that the safety and health of daeri drivers be highlighted., Graphical Abstract

Osteoarthritis (OA) causes chronic pain, physical disability, and mental health deterioration and reduces the quality of life of patients. Sleep is an important factor in the recovery, and adequate sleep is important for quality of life. Several features of patients with OA can affect sleep time, and sleep also affects OA. We investigated the relationship between OA and sleep duration. Data for 2010–2012 were collected from the Korea National Health and Nutrition Examination Survey. We included 11,540 participants (4915 men and 6625 women). Patients with OA were defined as participants with knee/hip joint pain and radiographic changes of the knee/hip joints. Sleep time was divided into 4 sections as follows: (1) 0–3 h, (2) 4–5 h, (3) 6–7 h, and (4) ≥ 8 h. Sleep time of 6 and 7 h was the most frequent and set as the reference time. In the multiple logistic regression model, the patients who slept for 0–3 and 4–5 h had odds ratios (ORs) of 2.28 (95% confidence interval [CI] 1.14–4.55) and 1.38 (95% CI 1.01–1.89) for men and 1.63 (95% CI 1.19–2.24) and 1.26 (95% CI 1.08–1.47) for women, respectively, for having OA. The prevalence of OA was lowest in the participants who had 6–7 h of sleep and progressively increased with shorter sleep time. Thus, sleep duration was significantly associated with OA.

Aim Osteoarthritis (OA) is a chronic disease and has become a major health problem in recent years. OA causes chronic pain and disability and can induce mental disorders such as stress perception, depression and suicidal ideation. We investigated the incidence of perceived stress, depressed mood and suicidal ideation in OA patients, using the 2010–2012 Korea National Health and Nutrition Examination Survey (KNHANES). Method A total of 8271 participants were included (3580 male and 4691 female). OA patients were defined as participants with knee/hip joint pain and radiographic changes of the knee/hip joints. Mental disorders included stress perception, depression and suicidal ideation. Odds ratios (ORs) and 95% confidence intervals (95% CIs) for mental disorders were calculated according to the OA. Results In the multiple logistic regression model, compared to the non-OA group, the ORs of high stress perception, depression and suicidal ideation were 1.59 (95% CI 1.10–2.31), 1.52 (95% CI 1.01–2.29) and 1.90 (95% CI 1.33–2.72), respectively, in male, and 1.41 (95% CI 1.19–1.68), 1.27 (95% CI 1.04–1.54) and 1.49 (95% CI 1.25–1.78), respectively, in female. Conclusion OA is associated with impaired mental health. OA patients had high stress perception, depression and suicidal ideation. More numbers of male with OA had much more mental disorders than female with OA.

Introduction The individual and combined effect of occupational noise and vibration exposures, on workers’ health has not been thoroughly investigated. In order to find better ways to prevent and manage workers’ headache, this study aimed to investigate the effects of occupational noise and vibration exposure on headache/eyestrain. Methods We used data from the fourth Korean Working Condition Survey (2014). After applying inclusion and exclusion criteria, 25,751 workers were included. Occupational noise and vibration exposure and the prevalence of headache/eyestrain were investigated by self-reported survey. Chi-square tests were used to compare differences in baseline characteristics between the group with headache/eyestrain and the group without. Odds ratios and 95% confidence intervals were estimated using a logistic regression model adjusted for several covariates. Area under the receiver operating characteristics curve (AUROC) analysis was used to evaluate the effect of occupational noise and/or vibration exposure. Results Among the 25,751 study subjects, 4,903 had experienced headache/eyestrain in the preceding year. There were significant differences in age, education level, household income, occupational classification, shift work, occupational vibration exposure, and occupational noise exposure between the two groups (all p

Osteoarthritis (OA) is a considerable health problem worldwide. It is known to be associated with certain occupational risk factors. We examined the prevalence rate of OA by occupational cluster. Data were collected from the Korea National Health and Nutrition Examination Surveys (2010-2013). The total number of unweighted sample size was 9,905 participants: 4,460 men and 5,445 women, and OA prevalence was 5.3% and 18.4% respectively. OA patients were defined as participants with knee/hip joint pain and radiographic change of knee/hip joint. Occupational type was classified as either white, pink, blue, or green collar based on the occupational characteristics following physical demand: white for manager and professionals; pink for clerks and service/sales workers; blue for craft/trade workers, machine operators and assemblers, and elementary manual workers; and green for agricultural/fishery workers. We calculated the odds ratios (ORs) and 95% confidence intervals (95% CI) for the odds of a participant's having OA according to the occupational cluster, with gender stratification. The multiple logistic regression model showed that, compared to the white collar group, the ORs of the pink, blue, and green collar workers were 1.23 (95% CI 0.64-2.36), 1.85 (95% CI 1.18-2.88), and 2.91 (95% CI 1.86-4.54), respectively, in males, and 2.53 (95% CI 1.71-3.73), 2.86 (95% CI 1.94-4.21), and 3.90 (95% CI 2.60-5.83), respectively in females. The prevalence rate of OA was associated with the occupational cluster, in order from highest to lowest: green, blue, pink, and white collar.

Objectives We aimed to investigate the association socioeconomic status and unmet healthcare need in victims of occupational accident. Methods Data from second Panel Study of Worker’s Compensation Insurance was used, which included 1,803 participants. Odds ratio and 95% confidence intervals for unmet healthcare need to participants with a lower socioeconomic status and other socioeconomic statuses were investigated using multivariate regression analysis. Results Among all participants, 103 had unmet healthcare need, whereas 1,700 did not. After adjusting for sex, age, education level, smoking, drinking alcohol, having chronic disease, working period, occupational accident recovery period, occupational accident type, disability status, disability rating, and economic participants, the odds ratio of unmet healthcare need in participants with a lower socioeconomic status were 2.48 (95% confidence interval 1.59–3.88), compared to participants with other socioeconomic statuses. Conclusions The victims of occupational accident who has a lower socioeconomic status were more likely to have unmet healthcare need in comparison to having other socioeconomic statuses.

Objectives This study aims to investigate associated factors including the physician and the employer of successful return to work (RTW) in occupationally injured workers. Methods This study is based on the first panel study of workers’ compensation insurance (PSWCI), published in June 2014. The PSWCI is a sample survey of occupationally injured workers who completed medical care in 2012 (89,921 people). A total of 2000 subjects were sampled based on sex, age, nine metropolitan-based regions, disability ratings, duration of rehabilitation, and whether vocational rehabilitation service was used. We divided the study population into two groups: return to work (RTW) group (job retention, reemployment, unpaid family worker, and self-employment), and non-RTW group (joblessness and economical inactivity). The odds ratios (ORs) and 95 % confidence intervals (CI) related to differences in basic characteristics, part of physician and employer-related factors between those who succeeded to RTW and those who did not were measured using multivariable logistic regression model. Results The success of RTW is 70.6 % (n = 1412) among participants. The ORs (95 % CI) of the participants belonging to RTW who received periodic recovery assessment from the medical care institution and the physician are 1.51 (1.07–2.13). The ORs (95 % CI) are 1.68 (1.05–2.69) for the RTW group who received work ability assessment and referral for vocational return. When the employer maintains the relationship with the occupationally injured worker, the worker has 1.39 times higher odds (95 % CI: 1.41–2.26) of the RTW group compared to the non-RTW group. Conclusions The physician and the employer have a significant impact on the RTW.

The primary objective of this study was to estimate the association between blood mercury levels and overweight in Korean adults. We analyzed cross-sectional data from 9228 participants (4283 men and 4945 women) who completed the Korean National Health and Nutrition Examination Survey (KNHANES), 2007-2013. The population was divided into two groups according to the body mass index (BMI) and waist circumference (WC). Blood mercury levels were analyzed using a gold amalgam method with a DMA-80 instrument, categorized into quartiles, and stratified by sex. After adjusting for all covariates, blood mercury was significantly associated with overweight in all subjects. According to the BMI criteria, the adjusted odds ratio of being in the highest blood mercury quartile was 1.75 (95 % confidence interval [CI], 1.53-2.01) overall, 2.09 (95 % CI, 1.71-2.55) in men, and 1.58 (95 % CI, 1.32-1.89) in women. According to the WC criteria, the adjusted odds ratio of being in the highest blood mercury quartile was 1.85 (95 % CI, 1.49-2.30) in men and 1.96 (95 % CI, 1.62-2.36) in women compared to the lowest quartile. Additionally, a trend in overweight across increasing blood mercury levels was observed by the p for trend test in the multiple diagnostic criteria.

Background Dry Eye Syndrome (DES) is a broad spectrum of uncomfortable ocular conditions that are caused by reduced production of tears or an increased tear evaporation rate. This study evaluated the relationship between symptoms of DES and occupational characteristics to identify the occupation-dependent differences in the prevalence of symptoms of DES using the Korean National Health and Nutrition Examination Survey V (2010–2012) data. Methods A total of 6023 participants were included (3203 men and 2820 women). Questionnaires and physical examinations were used to record clinical characteristics, occupational characteristics and medical history. Odds ratios (ORs) and 95 % confidence intervals (95 % CIs) for symptoms of DES were calculated according to the occupational characteristics. Results Among the participants, 963 persons (16.0 %) had symptoms of DES. An increased risk (relative to the green-collar group) was observed for the ordinary white-collar (OR, 1.73; 95 % CI, 1.73–1.41), executive white-collar (OR, 1.40; 95 % CI, 1.02–1.92) and skilled blue-collar (OR, 1.44; 95 % CI, 1.04–2.00) groups. Furthermore, paid workers had a significantly higher risk of dry eye symptoms (OR, 1.21; 95 % CI, 1.02–1.45), compared to self-employed workers. Conclusion Our study is the first research to reveal that white-collar workers have a higher risk of symptoms of DES than blue-collar workers, that skilled blue-collar workers have a higher risk than unskilled blue-collar workers, and that paid workers have a higher risk than self-employed workers.

Objective The aim of the present study was to investigate the association between sleep duration and dry eye syndrome (DES) symptoms. Methods We investigated 15,878 subjects (male = 6684; female = 9194) aged 20 years and older who underwent physical examinations and completed a self-report questionnaire and other anthropometric variables from the fifth Korean National Health and Nutrition Examination Survey (KNHANES) 2010–2012. Odds ratios (OR) and 95% confidence intervals (95% CI) for DES according to sleep duration were calculated using multiple logistic regression models. Results Compared to that in an optimal sleep group (6–8 h/day), OR (95% CI) DES prevalence after adjusting for age, gender, sociodemographic factors (educational level, occupation, household income, and residence), and health behaviors (smoking habit, alcohol consumption, and level of exercise) was 1.20 (1.05–1.36) for a mild short sleep group (5 h/day) and 1.29 (1.08–1.55) for a severe short sleep group (≤4 h/day). Conclusion Our results revealed that DES increased at shorter sleep durations.

We examined associations between hospital quality in the workers’ compensation system and injured patients’ return to work after controlling for injury severity, occupational factors, and demographic factors. Return to work data of injured workers were constructed from 2 datasets: 23,392 patients injured in 2009–2011 from the Korea Workers’ Compensation & Welfare Service and return to work data from Korea Employment Information Services. After de-identifying the data, quality scores were matched for each hospital that cared for injured patients. Injury severity was measured by Abbreviated Injury Scales. Relative risk and 95% confidence interval were calculated using log binomial regression models. After adjusting for age, sex, injury severity, occupation, factory size, city, and hospital type, the relative risk (95% confidence interval) for the total score was 1.04 (1.02–1.06), 1.06 (1.04–1.09), and 1.07 (1.05–1.10) in the 2nd, 3rd, and 4th quartiles, respectively, compared to the 1st quartile. The RR (95% CI) in the 2nd, 3rd, and 4th quartiles was 1.05 (1.02–1.07), 1.05 (1.02–1.08), and 1.06 (1.04–1.09) for the process score; and 1.02 (1.01–1.04), 1.05 (1.03–1.07), and 1.06 (1.04–1.09) for the outcome score compared to the 1st quartile score, respectively. In conclusion, our study design with blinded merge methods shows that total, process, and outcome qualities are related to the return to work of injured workers after controlling for other factors., Graphical Abstract

BACKGROUND: Long working hours are a worldwide problem and may increase the risk of various health issues. However, the health effects of long working hours on suicidal thoughts have not been frequently studied. Our goal was to investigate the relationship between long working hours and suicidal thoughts in the rapidly developing country of Korea. METHODS: Data from 12,076 participants (7,164 men, 4,912 women) from the 4th and 5th Korean National Health and Nutrition Examination Surveys were used for the current analysis. Multivariate logistic regression models were used to estimate odds ratios and 95% confidence intervals for suicidal thoughts. Combined effects of long working hours and lower socioeconomic status or sleep disturbance were also estimated. RESULTS: Compared to groups who worked less than 52 hours per week, odds ratios (95% confidence intervals) for suicidal thoughts in groups who worked 60 hours or more per week were 1.36 (1.09-1.70) for males and 1.38 (1.11-1.72) for females, even after controlling for household income, marital status, history of hypertension or diabetes mellitus, health-related behaviors, and past two weeks' experience of injury, intoxication, or acute or chronic diseases, as well as type of work. The combined effects of long working hours with lower socioeconomic status, or with sleep disturbance, were also significantly higher compared to participants who worked less than 52 hours per week with higher socioeconomic status, or with 6-8 hours of nighttime sleep. CONCLUSION: In this study, long working hours were linked to suicidal thoughts for both genders. Additionally, the odds of those suicidal thoughts were higher for lower socioeconomic groups. To prevent adverse psychological health problems such as suicidal thoughts, a strategy regarding long working hours should be investigated. Language: en

Objectives We aimed to investigate the association between concealing emotions at work and medical utilization. Methods Data from the 2007–2009 4th Korea National Health and Nutrition Examination Survey (KNHANES IV) was used, 7,094 participants (3,837 males, 3,257 females) aged between 20 and 54 who were economically active and completed all necessary questionnaire items were included. Odds ratios (ORs) and 95% confidence intervals (95% CI) for differences in hospitalization, outpatient visits, and pharmaceutical drug use between those who concealed their emotions and those who did not were investigated using logistic regression models with and without gender stratification. Results Among those who concealed their emotions (n = 2,763), 47.4% were females, and 50.1% had chronic disease. In addition, 9.7% of the concealing emotions group had been hospitalized within the last year, 24.8% had been outpatients in the last two weeks, and 28.3% had used pharmaceutical drugs in the last two weeks. All ORs represent the odds of belonging to the concealing emotions group over the non-concealing emotions group. After adjustment for individual, occupational, socioeconomic and disease factors, the adjusted ORs (95% CI) in hospitalization are 1.29 (1.08 ~ 1.53) in the total population, 1.25 (0.98 ~ 1.60) in males and 1.30 (1.02 ~ 1.66) in females, in outpatient visits are 1.15 (1.02 ~ 1.29) in the total population, 1.05 (0.88 ~ 1.24) in males and 1.25 (1.06 ~ 1.47) in females and in pharmaceutical drug use are 1.12 (1.01 ~ 1.25) in the total population, 1.08 (0.92 ~ 1.27) in males and 1.14 (0.98 ~ 1.33) in females. Conclusions Those who concealed their emotions at work were more likely to use medical services. Moreover, the health effects of concealing emotions at work might be more detrimental in women than in men.

Background The aim of this paper was report first case of renal cell carcinoma developed in a worker who worked in an automobile manufacture line which handles trichloroethylene in Korea. Case presentation To clarify the relationship between the onset of renal cell carcinoma in 52-years old male worker and the exposure to trichloroethylene, document studies and work environment measurement were done. Past work environment exposure data were reviewed and medical history and surgery records of the worker were also reviewed. The patient had no personal risk factor related to renal cell carcinoma except for his smoking habit of quarter a pack per day for twenty years, and since trichloroethylene was not part of measurement criteria, past work environment risk assessment data could not verify the exposure. The exposure level is deduced by analyzing material exposure level of work environments which has similar processes in data from revised research of chemical exposure standard and work environment validity assessment. Evaluation Committee of Epidemiologic Survey decided that there are relevant relationship between the exposure and the disease, though we do not have exact data during that period, most experts agree that in every factories they used trichloroethylene without any direction. Conclusions From the relevant medical history and the results of the usage of trichloroethylene in the relevant industries, and initial discovery of renal cell carcinoma at health inspection sonogram in 2001, it can be concluded that suggests significant causal relationship between the exposure to trichloroethylene and renal cell carcinoma onset, thus reporting it to be the first domestic case declared to be occupational disease.