Association between ergonomic risk exposures and insomnia symptoms: a mediation analysis of the 5th Korean working conditions survey.

BACKGROUND: This study investigates the relationship between ergonomic risk exposures and insomnia symptoms, using data representative of Korea's general working population. METHODS: Data from the 5th Korean Working Conditions Survey were used for this study. The eligible population (employees) for the current study was 37,026. Insomnia symptoms were estimated using the minimal insomnia symptom scale (MISS) questionnaire. Logistic regression analysis was conducted to explore the association between ergonomic risks and insomnia symptoms. RESULTS: All the investigated ergonomic risks increased odd ratios (ORs) for insomnia symptoms: Tiring or painful positions (OR, 1.64; 95% CI, 1.43-1.88); lifting or moving heavy loads (OR, 2.33; 95% CI, 1.99-2.71); long periods of standing (OR, 1.47; 95% CI, 1.29-1.69); and repetitive hand or arm movements (OR, 1.46; 95% CI, 1.29-1.67). The mediated proportion of musculoskeletal pain was 7.4% (95% CI, 5.81-10.13), and the mediated proportion of feeling of exhaustion was 17.5% (95% CI, 5.81-10.13). CONCLUSIONS: This study provides evidence for the relationship between ergonomic risks and insomnia symptoms, for which musculoskeletal pains and the feeling of exhaustion may be potential mediators.

Occupational physical activity, not leisure-time physical activity, is associated with increased high-sensitivity C reactive protein levels.

OBJECTIVE: This study aims to explore the association between physical activity and high-sensitivity C reactive protein, based on different types of physical activity-occupational and leisure time. METHODS: Using cross-sectional data from the Korea National Health and Nutrition Examination Survey 2015-2018, we explored the association between different types of self-reported physical activity and high levels of high-sensitivity C reactive protein (>3 mg/L). We estimated the ORs for high-level high-sensitivity C reactive protein using multiple logistic regression models after adjusting for covariates from 12 970 eligible subjects (mean age 44.8). RESULTS: Compared with subjects who did not engage in moderate-to-vigorous level of occupational physical activity (OPA), the group that engaged in moderate-to-vigorous level of OPA showed a significantly high OR (1.32, 95% CI (1.03 to 1.69)), whereas the group that engaged in moderate-to-vigorous level of leisure-time physical activity (LPA) yielded a low OR (0.84, 95% CI (0.69 to 1.01)). The group that engaged in moderate-to-vigorous level of OPA but not LPA showed a significantly high OR (1.76, 95% CI (1.27 to 2.45)) compared with subjects who engaged in moderate-to-vigorous level of LPA but not in OPA. CONCLUSIONS: OPA is directly associated with high C reactive protein levels, suggesting that it increases the risk of inflammation.

The relationship between the pattern of shift work and sleep disturbances in Korean firefighters.

PURPOSE: Sleep disturbances are prevalent in firefighters, but the relationship between patterns of shift work and sleep disturbances has not yet been investigated. Here, this relationship has been evaluated in Korean firefighters. METHODS: A cross-sectional study was conducted using an online questionnaire, which captured demographic, psychosocial and work-related characteristics. Sleep disturbance was assessed using the insomnia severity index (ISI). The relationship between insomnia and work-related factors (including type of shift work and the frequency of emergency events and off-duty work which means overtime work on off days) was analyzed. RESULTS: A total of 9810 firefighters completed the survey, representing approximately 21.5% of all Korean firefighters; data from 9738 subjects were included in the analysis. All firefighter roles were significantly associated with insomnia; the odds ratio (OR) was 2.456 (95% confidence interval [CI] 1.461-4.128) for fire suppression and 1.871 (95% CI 1.105-3.167) for the emergency medical services and rescue. However, the pattern of shift work did not show a statistically significant relationship. The OR increased along with the frequency of emergency events and off-duty work (p value for trend < 0.05). CONCLUSIONS: This study found a significant association between the frequency of emergency and off-duty work and insomnia in Korean firefighters, whereas the pattern of shift work showed no significant relationship. Therefore, measures to reduce the frequency of emergency and off-duty work are required to prevent sleep disturbances in firefighters.

Impact of Epidermal Growth Factor Receptor Mutation on Clinical Outcomes of Nintedanib Plus Docetaxel in Patients with Previously Treated Non-Small Cell Lung Cancer from the Korean Named Patient Program.

OBJECTIVES: Anti-angiogenic agents are reported to exert clinical activity on epidermal growth factor receptor (EGFR) mutant non-small-cell lung cancers. We evaluated the clinical outcomes of nintedanib and docetaxel in refractory NSCLC according to EGFR mutation status during the Korean nintedanib named patient program. METHODS: Docetaxel was administered either 75 or 37.5 mg/m2 on D1, D8 q every 3 weeks for 4-6 cycles plus nintedanib 200 mg orally twice daily until disease progression or unacceptable toxicity. RESULTS: Sixty-two patients were enrolled for study. Twenty-eight patients with activating EGFR mutations progressed after EGFR-tyrosine kinase inhibitors (TKI) therapy and 25 out of 28 patients showing progression after platinum doublet chemotherapy were enrolled. The objective response rate was 29% and median PFS and OS were 3.9 months and 11.7 months. Based on the EGFR mutation status, the objective response rate was 39.3 vs. 21.9% (EGFR mut(+) vs. EGFR mut(-), p = 0.142) and median PFS was 6.5 vs. 3.3 months (EGFR mut(+) vs. EGFR mut(-), p = 0.009). No treatment-related deaths were reported. The most frequent drug-related adverse events (AE) were neutropenia (53.2%) and diarrhea (37.1%). Treatment in 12 patients (19.3%) was permanently discontinued due to AEs without disease progression. CONCLUSIONS: Our data indicated that nintedanib-docetaxel combination could be considered to be effective treatment in EGFR TKI-resistant EGFR mutant NSCLC.

A Prospective Observational Study Evaluating the Correlation of c-MET Expression and EGFR Gene Mutation with Response to Erlotinib as Second-Line Treatment for Patients with Advanced/Metastatic Non-Small-Cell Lung Cancer.

OBJECTIVES: We aimed to evaluate the prevalence and predictive role of c-MET expression and EGFR mutation in the efficacy of erlotinib in non-small-cell lung cancer (NSCLC). METHODS: We prospectively recruited 196 patients with stage IV or recurrent NSCLC treated with erlotinib after failure of first-line chemotherapy. Immunohistochemistry was used to evaluate c-MET overexpression, silver in situ hybridization (SISH) to assess gene copy number, and real-time polymerase chain reaction to detect EGFR mutations, respectively, in tumor tissue. RESULTS: The major histologic type was adenocarcinoma (66.8%). c-MET was overexpressed in 55.8% (87/156) and dominant in females as well as non-squamous histology. Although c-MET gene amplification and high polysomy were observed in 2.0% (3/152) and 11.2% (17/152), they did not correlate with any characteristics. EGFR mutation was detected in 13.1% (20/153). The objective response rate of erlotinib was higher (61.1 vs. 3.7%, p < 0.001) and the median progression-free survival (PFS) was longer (10.2 vs. 1.9 months, p < 0.001) in EGFR-sensitizing mutations. However, c-MET positivity did not show a significant correlation with response to erlotinib or PFS. CONCLUSION: We reconfirmed EGFR mutation as a strong predictive marker of NSCLC. However, c-MET positivity was not associated with response or PFS, although c-MET overexpression correlated with some clinical characteristics.

Evaluation for Fatigue and Accident Risk of Korean Commercial Bus Drivers.

Many Korean bus drivers work long hours, which causes fatigue and increased risk of accidents during driving. Their fatigue due to long working hours may cause a significant accident accompanied by injuries of the general population. The present study aimed to evaluate the fatigue and accident risk in Korean commercial bus drivers. The subjects were 16 city and express bus drivers with various work schedules: 2 shifts (2 shifts in a day), WR (duty-off), W2R (duty-duty-off), and W4R2 (duty-duty-duty-duty-off-off). We measured the subjects' heart rate in their workplace during their work and calculated relative heart rate (RHR) and maximum acceptable work time (MAWT), the maximum amount of time for which workers can sustain their workload without physical fatigue. Fatigue and risk index, which is a tool for assessing the risk from fatigue in the safety critical workers, was calculated using the subjects' work schedule. RHR ranged from 9.7 to 21.8% and MAWT was shorter than each subject's actual work hours. Fatigue (45.2-54.4) and risk indices (1.8) were high in WR schedule, which were higher than recommended value (30-35 for fatigue index and < 1.6 for risk index). According to these findings, Korean bus drivers worked long hours beyond their physical abilities, and the fatigue and risk indices were high, especially in WR schedule. It is necessary to prepare the policies to reduce the fatigue and accident risk in the Korean bus drivers including regulation for bus drivers' driving time restriction.

Belotecan/cisplatin versus etoposide/cisplatin in previously untreated patients with extensive-stage small cell lung carcinoma: a multi-center randomized phase III trial.

BACKGROUND: No novel chemotherapeutic combinations have demonstrated superior efficacy to etoposide/cisplatin (EP), a standard treatment regimen for extensive-stage small cell lung carcinoma (ES-SCLC) over the past decade. We aimed to compare the efficacy and safety of belotecan/cisplatin (BP) and EP regimens in chemotherapy- and radiotherapy-naïve patients with previously untreated ES-SCLC. METHODS: We conducted a multi-center, randomized, open-label, parallel-group, phase III clinical study. A total of 157 patients were recruited at 14 centers with 147 patients meeting the inclusion/exclusion criteria and randomized to either BP (n = 71) or EP (n = 76) treatment arms. A non-inferior response rate (RR) in the BP arm, analyzed by intent-to-treat analysis according to Response Evaluation Criteria in Solid Tumors version 1.0 criteria, was used as the primary endpoint. The secondary endpoints were progression-free survival (PFS) and overall survival (OS). RESULTS: In the BP arm, one patient had a complete response, 41 had a partial response (PR), and 17 had stable disease (SD). In the EP arm, 35 patients had PR and 28 had SD. The RR in the BP arm was non-inferior to the EP regimen in patients with ES-SCLC (BP: 59.2 %, EP: 46.1 %, difference: 13.1 %, 90 % two-sided confidence interval: -0.3-26.5, meeting the predefined non-inferiority criterion of -15.0 %). No significant differences in OS or PFS were observed between the treatment arms. Hematologic toxicities, including grade 3/4 anemia and thrombocytopenia, were significantly more prevalent in the BP arm than the EP arm. CONCLUSIONS: The RR to the BP regimen was non-inferior to the EP regimen in chemotherapy- and radiotherapy-naïve patients with previously untreated ES-SCLC. Hematologic toxicities were significantly more prevalent in the BP group, indicating that BP should be used with care, particularly in patients with a poor performance status. Further studies assessing PFS and OS are required to validate the superiority of the BP regimen. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT00826644 . Date of Registration: January 21, 2009.

Work-related musculoskeletal diseases and the workers' compensation.

The Industrial Accident Compensation Insurance Act (IACIA) regulates the workers' compensation insurance system and the standards for the recognition of occupational diseases (ODs). Since its establishment in 1994, the IACIA has been amended several times. Before 2008, the approval of compensation for work-related musculoskeletal diseases (WMSDs) was decided based on the recommendation of consultants of the Korea Workers' Compensation and Welfare Service (COMWEL). The IACIA was amended in 2008, and since then, the approval of compensation for occupational injuries has been decided based on the recommendation of COMWEL consultants, whereas the approval of compensation for ODs was decided based on the judgment of Committee on Occupational Diseases Judgment (CODJ) which was established in 2008. According to the 2013 amendment to the IACIA, degenerative musculoskeletal diseases among workers engaged in musculoskeletal-burdening work should be considered compensable ODs. Despite some commendable changes to the workers' compensation insurance system, other significant issues persist. To resolve these issues, related organizations including the associations of orthopedic surgery, neurosurgery, and occupational and environmental medicine; Ministry of Employment and Labor; and COMWEL need to work cooperatively.

Association between social jetlag and self-rated health: Evidence from Korean representative working population.

BACKGROUND: Social jetlag is a circadian misalignment that arises from a discrepancy between activity/sleep schedules on school/work days and free days. This study explored the correlation between social jetlag and self-rated health (SRH) in a representative sample of Korea. METHODS: This study included 8259 working population in the Korea National Health and Nutrition Examination Survey, 2016-2018. Social jetlag was calculated as the difference between the midpoint of sleep time on work day and work-free day. Five-point Likert scale of SRH was used to assess subjective health perception on general health conditions. Multiple logistic regression analysis was performed to calculate the odds ratios (ORs) and 95 % confidence interval (CI) for poor SRH in the 1-2 h or longer than 2 h social jetlag groups compared to that in the reference group (less than 1 h), after adjusting for age, sex, marital status, occupation, household income, and weekly working hours. RESULTS: The proportions of those with <1 h, 1-2 h, >2 h of social jetlag were 63.80 %, 25.67 %, and 10.53 %, respectively. The risk of poor SRH increased as social jetlag increased. Greater social jetlag was significantly associated with an increased likelihood of reporting poor SRH. The adjusted ORs for the groups with social jetlag between 1 and <2 h, and >2 h were 1.100 (95 % CI = 0.935-1.295), and 1.503 (95 % CI = 1.097-1.727), respectively. Moreover, the OR trend was statistically significant (p for trend = 0.008). CONCLUSION: This study found that social jetlag and poor SRH were significantly related in the Korean working population.

Gender-specific influence of socioeconomic status on the prevalence of migraine and tension-type headache: the results from the Korean Headache Survey.

BACKGROUND: Socioeconomic status plays an important role in pain coping strategy. Its influence on migraine and tension-type headache may differ by gender. This study aimed to evaluate how socioeconomic status affects the prevalence of migraine and tension-type headache by gender. METHODS: We used data from the Korean Headache Survey, a population-based sample of Koreans aged 19-69 years. Education level, district size, and household income were evaluated as socioeconomic variables. RESULTS: Among 1507 participants, the 1-year prevalence rates of migraine and tension-type headache were 8.7% [95% confidence interval (CI) 1.9-4.6%] and 29.1% (95% CI 25.7-32.5%) in women and 3.2% (95% CI 1.9-4.6%) and 32.5% (95% CI 29.1-35.9%) in men, respectively. In women, multiple regression analysis found that living in rural areas was related to higher prevalence of migraine [odds ratio (OR) 4.52, 95% CI 1.85-11.02] and lower prevalence of tension-type headache (OR 0.29, 95% CI 0.15-0.58) and college-level education was related to lower prevalence of tension-type headache (OR 0.37, 95% CI 0.18-0.74). In men, multiple regression analysis failed to reveal significant influences of any socioeconomic variable on the prevalence of migraine or tension-type headache. CONCLUSIONS: The influence of socioeconomic status on migraine and tension-type headache differs by gender, with women being more susceptible to socioeconomic influence.

Working hours and the regulations for night shift workers.

There are several types of shift work in Korea: rotating shift, 24-hour shift, day-night shift, fixed night work, and.so on. As a result of analyzing the 8th Korea National Health and Nutrition Examination Survey and the 6th Korean Working Condition Survey, Korean shift workers accounted for 11.6%-13.9% of wage workers. Weekly working hours of shift workers were 57.69 ± 1.73 (24-hours shift) and 49.97 ± 0.67 (fixed night shift), which were significantly longer than day workers. To prevent health consequences of night work, many countries regulate the working hours of night work not to exceed 7-9 hours a day. However, Korea does not regulate working hours for night work, and some occupations may work more hours than the prescribed overtime hours. To prevent health consequences and reduce working hours for Korean night shift workers, it is necessary to regulate the working hours of night shift workers by law.

Social jetlag and risk of depression: Results from the Korea National Health and Nutrition Examination Survey.

BACKGROUND: Social jetlag, which is the mismatch between endogenous rhythm and social timing, is prevalent among the working population. Social jetlag may result in mood changes; however, evidence of relationship between social jetlag and depressive disorders has not been fully verified. Hence, this study aimed to investigate the association between social jetlag and depressive symptoms in a representative working population of South Korea. METHODS: This study included 5447 Korean employees in the Korea National Health and Nutrition Examination Survey. Social jetlag was calculated as the difference between the midpoint of sleep time on weekdays and free days. Depressive symptoms were assessed using Patient Health Questionnaire-9. Multiple logistic regression was used to estimate the odds ratio after adjusting for confounding factors. Moreover, social jetlag and continuous depression scores were evaluated using linear regression and generalized additive models. RESULTS: The proportion of the participants who had >2 h of social jetlag was 10.26 %. Depressive symptoms increased as social jetlag increased. Multiple logistic regression analysis showed that the adjusted OR (95 % confidence interval) for 1 to 2 h of social jetlag was 1.355 (0.891-2.059) and for >2 h was 1.859 (1.084-3.187), which <1 h was reference. LIMITATIONS: This study used a cross-sectional design and measurements were based on self-reported scales. CONCLUSION: This study found that social jetlag and depressive symptoms were significantly related in the Korean working population.

Development of algorithm for work intensity evaluation using excess overwork index of construction workers with real-time heart rate measurement device.

Background: The construction workers are vulnerable to fatigue due to high physical workload. This study aimed to investigate the relationship between overwork and heart rate in construction workers and propose a scheme to prevent overwork in advance. Methods: We measured the heart rates of construction workers at a construction site of a residential and commercial complex in Seoul from August to October 2021 and develop an index that monitors overwork in real-time. A total of 66 Korean workers participated in the study, wearing real-time heart rate monitoring equipment. The relative heart rate (RHR) was calculated using the minimum and maximum heart rates, and the maximum acceptable working time (MAWT) was estimated using RHR to calculate the workload. The overwork index (OI) was defined as the cumulative workload evaluated with the MAWT. An appropriate scenario line (PSL) was set as an index that can be compared to the OI to evaluate the degree of overwork in real-time. The excess overwork index (EOI) was evaluated in real-time during work performance using the difference between the OI and the PSL. The EOI value was used to perform receiver operating characteristic (ROC) curve analysis to find the optimal cut-off value for classification of overwork state. Results: Of the 60 participants analyzed, 28 (46.7%) were classified as the overwork group based on their RHR. ROC curve analysis showed that the EOI was a good predictor of overwork, with an area under the curve of 0.824. The optimal cut-off values ranged from 21.8% to 24.0% depending on the method used to determine the cut-off point. Conclusion: The EOI showed promising results as a predictive tool to assess overwork in real-time using heart rate monitoring and calculation through MAWT. Further research is needed to assess physical workload accurately and determine cut-off values across industries.

Real-World Study of Osimertinib in Korean Patients with Epidermal Growth Factor Receptor T790M Mutation-Positive Non-Small Cell Lung Cancer.

PURPOSE: Although osimertinib is the standard-of-care treatment of epidermal growth factor receptor (EGFR) T790M mutation-positive non-small cell lung cancer, real-world evidence on the efficacy of osimertinib is not enough to reflect the complexity of the entire course of treatment. Herein, we report on the use of osimertinib in patients with EGFR T790M mutation-positive non-small cell lung cancer who had previously received EGFR tyrosine kinase inhibitor (TKI) treatment in Korea. MATERIALS AND METHODS: Patients with confirmed EGFR T790M after disease progression of prior EGFR-TKI were enrolled and administered osimertinib 80 mg daily. The primary effectiveness outcome was progression-free survival, with time-to-treatment discontinuation, treatment and adverse effects leading to treatment discontinuation, and overall survival being the secondary endpoints. RESULTS: A total of 558 individuals were enrolled, and 55.2% had investigator-assessed responses. The median progression-free survival was 14.2 months (95% confidence interval [CI], 13.0 to 16.4), and the median time-to-treatment discontinuation was 15.0 months (95% CI, 14.1 to 15.9). The median overall survival was 36.7 months (95% CI, 30.9 to not reached). The benefit with osimertinib was consistent regardless of the age, sex, smoking history, and primary EGFR mutation subtype. However, hepatic metastases at the time of diagnosis, the presence of plasma EGFR T790M, and the shorter duration of prior EGFR-TKI treatment were poor predictors of osimertinib treatment. Ten patients (1.8%), including three with pneumonitis, had to discontinue osimertinib due to severe adverse effects. CONCLUSION: Osimertinib demonstrated its clinical effectiveness and survival benefit for EGFR T790M mutation-positive in Korean patients with no new safety signals.

The association between nonstandard work and occupational injury in Korea.

BACKGROUND: The number of workers who died due to occupational injury in Korea as of 2007 was 1,383. The aim of this study was to identify whether there were any differences in the risk of occupational injury between nonstandard workers (temporary workers and/or subcontract workers) and regular workers. METHODS: 1,576 injured workers, selected from National Health Insurance and National Workers' Compensation Insurance, were interviewed via telephone survey using standardized questionnaires in 2007. The control group was 1,500 workers matched for age, gender, and severity of injury. A multivariate logistic regression model was used to analyze the association between the type of nonstandard work and occupational injury. RESULTS: Nonstandard temporary workers were more likely to be injured than regular workers even if other related factors of occupational injury were statistically adjusted (adjusted odds ratio, OR 2.87, 95% confidence interval 2.37-3.49). CONCLUSIONS: The reason why the risks of nonstandard workers are higher than those of regular workers is that nonstandard workers are placed in poor working conditions.

Estimation of maximal oxygen uptake without exercise testing in Korean healthy adult workers.

Maximal oxygen uptake is generally accepted as the most valid and reliable index of cardiorespiratory fitness and functional aerobic capacity. The exercise test for measuring maximal oxygen uptake is unsuitable for screening tests in public heath examinations, because of the potential risks of exercise exertion and time demands. We designed this study to determine whether work-related physical activity is a potential predictor of maximal oxygen uptake, and to develop a maximal oxygen uptake equation using a non-exercise regression model for the cardiorespiratory fitness test in Korean adult workers. Study subjects were adult workers of small-sized companies in Korea. Subjects with history of disease such as hypertension, diabetes, asthma and angina were excluded. In total, 217 adult subjects (113 men of 21-55 years old and 104 women of 20-64 years old) were included. Self-report questionnaire survey was conducted on study subjects, and maximal oxygen uptake of each subject was measured with the exercise test. The statistical analysis was carried out to develop an equation for estimating maximal oxygen uptake. The predictors for estimating maximal oxygen uptake included age, gender, body mass index, smoking, leisure-time physical activity and the factors representing work-related physical activity. The work-related physical activity was identified to be a predictor of maximal oxygen uptake. Moreover, the equation showed high validity according to the statistical analysis. The equation for estimating maximal oxygen uptake developed in the present study could be used as a screening test for assessing cardiorespiratory fitness in Korean adult workers.

Application of several machine learning algorithms for the prediction of afatinib treatment outcome in advanced-stage EGFR-mutated non-small-cell lung cancer.

BACKGROUND: The present study aimed to evaluate the performance of several machine learning (ML) algorithms in predicting 1-year afatinib continuation and 2-year survival after afatinib initiation and to identify the differences in survival outcomes between ML-classified strata. METHODS: Data that were also used in the RESET study were retrospectively collected from 16 hospitals in South Korea. A stratified random sampling method was applied to split the data into training and test sets (70:30 split ratio). Clinical information, such as age, sex, tumor stage, smoking, performance status, metastasis, type of metastasis, dose adjustment, and pathologic information on EGFR mutations were inputted. Training was performed using eight ML algorithms: logistic regression, decision tree, deep neural network, random forest, support vector machine, boosting, bagging, and the naïve Bayes classifier. The model performance was assessed based on sensitivity, specificity, and accuracy. Area under the receiver operator characteristic curve (AUC) was calculated and compared between the ML models using DeLong's test. A Kaplan-Meier (KM) curve was used to visualize the identified strata obtained from the ML models. RESULTS: No significant differences in the input variables were observed between the training and test datasets. The best-performing models were support vector machine in predicting 1-year afatinib continuation (AUC 0.626) and decision tree in 2-year survival after afatinib start (AUC 0.644), although the performances of the ML models were comparable and did not display any predictive roles. KM analysis and log-rank test revealed significant differences between the strata identified from the ML model (p < 0.001) in terms of both time-on-treatment (TOT) and overall survival (OS). CONCLUSION: The performances of ML models in our study found no discernible roles in predicting afatinib-related outcomes, although the identified strata revealed different TOT and OS in the KM analysis. This implies the strength of ML in predicting the survival outcome, as well as the limitation of electronic medical record-based variables in ML algorithms. Careful consideration of variable inclusion is likely to improve the general model performance.

Association between sleep quality and type of shift work in Korean firefighters.

Background: Shift work that interferes with normal sleep patterns, is known to be a cause of sleep disturbance and has been studied through various occupational groups. However, it is not known which shift type is better for sleep health. Methods: This study included 568 firefighters. Sleep quality was evaluated using Pittsburgh Sleep Quality Index. Sleep quality was categorized into 2 groups; good quality (≤ 5 points) and poor quality (≥ 6 points). Demographic variables, depression, anxiety, type of shift, and job were collected by self-reported questionnaires. The χ2 test, t-test, and multiple logistic regression analysis were used to evaluate the effect of shift type on the sleep quality of firefighters. Results: Three hundred thirty-seven firefighters (59.3%) have poor sleep quality. Compared to day workers, the odds ratios (ORs) of poor sleep quality were 2.169 (95% confidence interval: 1.137-4.134) in 6-day cycle, 2.161 (1.150-4.062) in 9-day cycle, 1.805 (1.087-2.997) in 21-day cycle, and 1.485 (0.718-3.069) in 3-day cycle. The ORs of poor sleep quality were 1.697(1.021-2.823) in fire suppression and 2.325 (1.213-4.455) in emergency medical service compared to administration. Conclusions: All shift work type except for the 3-day cycle was associated with poor sleep quality compared to day work.

Comparative analyses of occupational injuries among temporary agency worker and direct contract workers: Findings from the Korea Health Panel 2009-2018.

OBJECTIVES: Several studies have reported health or safety risk of temporary agency workers (TAW). Since most of the studies are just cross-sectional studies, we intended to identify the risk of occupational injury in TAW, using longitudinal study design. METHODS: The Korea Health Panel 2009-2018 data were used in the study. For the statistical analysis of this study, we used a panel logit model to identify the risk of occupational injury in TAW compared to direct contract workers (DCW). RESULTS: There was no significant difference in risk of occupational injury between TAW and DCW among the overall population (adjusted OR 0.920, 95% CI 0.600-1.411). However, there was a significant increase in occupational injury in women (adjusted OR 2.134, 95% CI 1.092-4.170) and the "19-34" age group (adjusted OR 2.744, 95% CI 1.103-6.825) of TAW. CONCLUSIONS: This study provides evidence for vulnerable groups such as women and younger age groups in the relationship between TAW and occupational injury.

Nypa fruticans Wurmb inhibits melanogenesis in isobutylmethylxanthine­treated melanoma via the PI3K/AKT/mTOR/CREB and MAPK signaling pathways.

Malignant melanoma is responsible for 3.0 and 1.7% of cases of tumor incidence and tumor-associated mortality, respectively, in the Caucasian population. Melanoma is a type of skin cancer that occurs when melanocytes mutate and divide uncontrollably. Nypa fruticans Wurmb (NF) is abundant in phytochemicals (polyphenols and flavonoids) and is traditionally used to treat diseases of the respiratory tract. The present study investigated the inhibitory effect of the ethyl acetate fraction of NF (ENF) on melanogenesis-related factors in isobutylmethylxanthine-treated B16F10 melanoma cells. Phenolics and flavonoids (caffeic acid, catechin, epicatechin and hirsutine) in ENF were analyzed via liquid chromatography-mass spectrometry. In addition, the main factors involved in melanogenesis were identified using immunoblotting, reverse transcription-polymerase chain reaction (RT-PCR), RT-quantitative PCR and immunofluorescence. ENF significantly suppressed the expression of tyrosinase (TYR) and TYR-related proteins 1 and 2 (TYRP-1/2), which are the main factors involved in melanogenesis. ENF also inhibited the expression of microphthalmia-associated transcription factor (MITF) by phosphorylating the related cell signaling proteins (protein kinase B, mammalian target of rapamycin, phosphoinositide 3-kinase and cAMP response element-binding protein). Furthermore, ENF inhibited the phosphorylation of extracellular signal-regulated kinase and thereby downregulated melanogenesis. In conclusion, ENF inhibited melanogenesis by suppressing MITF, which controls TYRP-1/2 and TYR. These results suggested that ENF may be a natural resource that can inhibit excessive melanin expression by regulating various melanogenesis pathways.