Metabolic Syndrome and the Increased Risk of Medically Certified Long-term Sickness Absence: A Prospective Analysis Among Japanese Workers.

BACKGROUND: Metabolic syndrome (MetS) has been associated with various chronic diseases that may lead to long-term sickness absence (LTSA), but there is lacking information on the direct association between MetS and LTSA. The present study aimed to investigate the all-cause and cause-specific associations between MetS and the risk of medically certified LTSA among Japanese workers. METHODS: We recruited 67,403 workers (57,276 men and 10,127 women), aged 20-59 years from 13 companies in Japan during their health check-ups in 2011 (11 companies) and 2014 (2 companies), and we followed them for LTSA events (≥30 consecutive days) until March 31, 2020. MetS was defined according to the Joint Interim Statement. A Cox proportional hazards regression model was used to estimate hazard ratios (HRs) and its 95% confidence intervals (CIs) for LTSA associated with MetS and its components. RESULTS: During 408,324 person-years of follow-up, 2,915 workers experienced LTSA. The adjusted HR for all-cause LTSA was 1.54 (95% CI, 1.41-1.68) among those with MetS compared to those without MetS. In cause-specific analysis, HRs associated with MetS significantly increased for LTSA due to overall physical disorders (1.76); cardiovascular diseases (3.16); diseases of the musculoskeletal system and connective tissue (2.01); cancers (1.24); obesity-related cancers (1.35); mental, behavioral, and neurodevelopmental disorders (1.28); reaction to severe stress and adjustment disorders (1.46); and external causes (1.46). The number of MetS components were also significantly associated with increased LTSA risk. CONCLUSION: MetS was associated with an increase in the risk of LTSA due to various diseases among Japanese workers.

[Current issues related to education in the five core disciplines of public health at the school of public health in a private university].

Objectives　In Japan, schools of public health (SPH) have engaged in professional education focusing on five core disciplines: epidemiology, biostatistics, social and behavioral science, health policy and management, and occupational and environmental health. However, empirical information is lacking regarding the current state of this education and its associated challenges in Japan. In this article, we showcase this issue, using the master of public health (MPH) course at Teikyo University Graduate School of Public Health (Teikyo SPH) as an example.Methods　We summarized the current objectives and classes required to complete the MPH course at Teikyo SPH, using the course guideline published in 2022. Current issues and possible future directions in the course were summarized based on the opinions of Teikyo SPH faculty members.Results　For epidemiology, lectures and exercises were designed to focus on how to formulating public health issues, collecting and evaluating data, and causal inference. Issues related to the design included ensuring that students had the necessary skills to apply epidemiology to emerging issues, and catching the course up with evolving techniques. For biostatistics, lectures and exercise classes focused on understanding data and statistics, as well as performing analyses. Issues included the understanding of theories, setting the course level, and a lack of appropriate education materials for emerging analytical methods. For social and behavioral science, lectures and exercise classes focused on understanding human behaviors and actions for problem solving. Issues included learning various behavioral theories in a limited timeframe, the gap between the lectures and various needs, and nurturing professionals who had the skills to perform in practical settings. For health policy and management, lectures, exercise classes, and practical training classes focused on identifying and solving problems in the community and around the world, and on integrating the disparate viewpoints of health economics and policy. Issues included few alumni who actually found work globally, a lack of students working in local or central administrations, and insufficient perspectives on rational/economic thinking and macro-economic transitions. For occupational and environmental health, lectures, exercise classes, and practical training classes focused on learning the occupational and environmental impacts of public health issues, and their countermeasures. Challenges included enriching the topics with regard to advanced technologies, environmental health, and socially vulnerable populations.Conclusion　Through these reflections on MPH education at Teikyo SPH, the following recommendations are considered essential in order to prepare improvements to the program: reorganizing the curriculum to meet the needs of the day, accepting students with various backgrounds, addressing the increasing knowledge and skills that need to be acquired by the students, and enhancing the powers of professors to implement changes.

Association of Changes of lifestyle behaviors before and during the COVID-19 pandemic with mental health: a longitudinal study in children and adolescents.

BACKGROUND: We examined the prospective associations of changes in lifestyle behaviors before/during the COVID-19 pandemic, namely physical activity and screen time, with mental health. Furthermore, the impacts of physical activity and screen time on mental health during the pandemic were examined cross-sectionally. METHODS: A two-wave longitudinal study was conducted among 2423 children and adolescents in Shanghai, China. Lifestyle behavior variables (physical activity and screen time) and psychological variables (depressive symptoms, anxiety, and stress) were measured using a self-reported questionnaire in January and March 2020. A series of multivariable logistic regressions were performed to examine the associations between changes in lifestyle behaviors in two waves and psychological problems. The combined associations of physical activity and screen time with psychological problems were also explored using the second wave data. RESULTS: Compared to students with persistently short screen time before and during the COVID-19 pandemic, those with prolonged screen time (OR = 1·36 for depression, OR = 1·48 for anxiety) and those with persistently long screen time (OR = 1·70 for depression, OR = 2·13 for anxiety) reported a higher risk of psychological symptoms. The association between changes in physical activity and psychological symptoms was not statistically significant after adjustment for demographic factors, socioeconomic status, and screen time. During the COVID-19 pandemic, engaging in longer screen time (OR = 1·44 for depression, OR = 1·55 for anxiety) was associated with worsened psychological conditions, while engaging in increased physical activity (OR = 0·58 for depression, OR = 0·66 for anxiety) was associated with better psychological conditions. CONCLUSIONS: Our study suggests that promoting physical activity and limiting leisure screen time during the COVID-19 pandemic are important to prevent and mitigate psychological problems in children and adolescents. Therefore, effective interventions targeting lifestyle behaviors are needed to protect children and adolescents' physical and mental health.

Overtime Work and the Incidence of Long-term Sickness Absence Due to Mental Disorders: A Prospective Cohort Study.

BACKGROUND: Although previous research has focused on the association between long working hours and several mental health outcomes, little is known about the association in relation to mental health-related sickness absence, which is a measure of productive loss. We aimed to investigate the association between overtime work and the incidence of long-term sickness absence (LTSA) due to mental disorders. METHODS: Data came from the Japan Epidemiology Collaboration on Occupational Health Study (J-ECOH). A total of 47,422 subjects were followed-up in the period between April 2012 and March 2017. Information on LTSA was obtained via a study-specific registry. Baseline information was obtained at an annual health checkup in 2011; overtime working hours were categorized into <45; 45-79; 80-99; and ≥100 hours/month. RESULTS: During a total follow-up period of 211,443 person-years, 536 people took LTSA due to mental disorders. A Cox proportional hazards model showed that compared to those with less than 45 hours/month of overtime work, those with 45-79 hours/month were at a lower risk of LTSA due to mental health problems (hazard ratio [HR] 0.63; 95% confidence interval [CI], 0.56-0.71) while those with overtime work of ≥100 hours/month had a 2.11 (95% CI, 1.12-3.98) times higher risk of LTSA due to mental health problems. CONCLUSION: Engaging in excessive overtime work was linked with a higher risk of LTSA due to mental health problems while the lower risk observed among individuals working 45-79 hours/month of overtime work might have been due to a healthy worker effect.

[A descriptive study on volunteer activities of providing meals during the early phase of the COVID-19 pandemic: clarifying the activities process and a preliminary investigation of the effect of activities on residents].

Objective　Although volunteer activities of providing meals have been conducted as measures to prevent isolation and loneliness and to secure meals, evidence is lacking regarding how to implement such activities. In this study, we describe the activities process at a community cafeteria located within a housing complex and operated by resident volunteers during the COVID-19 pandemic to provide inexpensive meals. We also report the preliminary results of the impact of such activities on the residents.Method　This case study was conducted at the community cafeteria Tate Kitchen 'Sakura' located within a Tokyo housing complex with a high ageing population. We collected data on the cafeteria activities during February to May, 2020. The data sources were daily activity records of the cafeteria, dialogues between volunteers and residents, and photos of activities. We qualitatively assessed the effects of the activities on the residents by classifying interviews with ten users and six volunteer staff based on the Kawakita Jiro (KJ) method.Results　During the observation period, regular meetings were held among board members and volunteers, and operations of the cafeteria were verified and modified by referring to the COVID-19 prevention guide for citizens, advice from health professionals, and residents' opinions. It was determined that activities would continue without cessation; the cafeteria, managed mainly by volunteers under the food hygiene control system required for commercial restaurants, was open five days a week to maintain food security and ensure the health of the residents. The number of meals sold at the cafeteria was halved in May (n = 2,149) as a result of the modification in operations. However, the number of meals delivered to each household increased from March because of increased demand. Qualitative analyses using KJ method showed that users perceived that these continued activities were effective in securing food, maintaining social interaction and promoting health, and health promotion, while volunteers perceived that the activities were effective in promoting social interaction and health.Conclusion　The resident volunteers continually confirmed their commitment to the principle of protecting food security and health within the community. They continued to operate the cafeteria by referring to available information on COVID-19 preventive measures, adopting the COVID-19 preventive measures, and involving all stakeholders. Qualitative analyses suggested that these continued efforts were useful for securing food and supporting health of the residents, looking after one other, and maintaining ties among residents.

Smoking Cessation, Weight Gain, and the Trajectory of Estimated Risk of Coronary Heart Disease: 8-Year Follow-up From a Prospective Cohort Study.

INTRODUCTION: The effect of weight gain following smoking cessation on cardiovascular risks is unclear. We aimed to prospectively investigate the association of weight gain following smoking cessation with the trajectory of estimated risks of coronary heart disease (CHD). METHODS: In a cohort of 18 562 Japanese male employees aged 30-64 years and initially free of cardiovascular diseases, participants were exclusively grouped into sustained smokers, quitters with weight gain (body weight increase ≥5%), quitters without weight gain (body weight increase <5% or weight loss), and never smokers. Global 10-year CHD risk was annually estimated by using a well-validated prediction model for the Japanese population. Linear mixed models and piecewise linear mixed models were used to compare changes in the estimated 10-year CHD risk by smoking status and weight change following smoking cessation. RESULTS: During a maximum of 8-year follow-up, both quitters with and without weight gain had a substantially decreased level of estimated 10-year CHD risk after quitting smoking, compared with sustained smokers (all ps for mean differences < .001). The estimated 10-year CHD risk within the first year after cessation decreased more rapidly in quitters without weight gain than in quitters with weight gain (change rate [95% confidence interval, CI] -0.90 [-1.04 to -0.75] vs. -0.40 [-0.60 to -0.19] % per year, p < .0001). Thereafter, the estimated 10-year CHD risk in both groups increased at similar rates (change rate [95% CI] -0.07 [-0.21 to 0.07] vs. 0.11 [-0.09 to 0.30] % per year, p = .16, from year 1 to year 2; and 0.10 [0.05 to 0.15] vs. 0.11 [0.04 to 0.18] % per year, p = .80, from year 2 to year 8). CONCLUSIONS: In this population of middle-aged, Japanese male workers, smoking cessation greatly reduces the estimated 10-year risk of CHD. However, weight gain weakens the beneficial effect of quitting smoking in a temporary and limited fashion. IMPLICATIONS: To the best of our knowledge, this study is the first to examine the effect of weight gain following smoking cessation on the trajectory of the absolute risk of CHD. Our data imply that the benefits of cessation for reducing the absolute risk of CHD outweigh the potential risk increase due to weight gain, and suggest that in order to maximize the beneficial effects of quitting smoking, interventions to control post-cessation weight gain might be warranted.

Smoking and Long-Term Sick Leave in a Japanese Working Population: Findings of the Japan Epidemiology Collaboration on Occupational Health Study.

BACKGROUND: Few studies have investigated the association between tobacco smoking and sick leave (SL) in Japan. METHODS: We followed 70 896 workers aged 20-59 years (60 133 males, 10 763 females) between April 2012 and March 2017. A Cox proportional hazards model was used to investigate the associations between smoking (smoking status and intensity) and long-term SL (ie, SL lasting ≥30 consecutive days). Cause-specific analyses were also conducted. RESULTS: A total of 1777 people took long-term SL during a follow-up of 307 749 person years. Compared with never-smokers, current smokers were at a higher risk of long-term SL (hazard ratio [HR] = 1.32; 95% confidence interval [CI] = 1.19 to 1.48). Cause-specific analyses revealed that current smoking was associated with a higher risk of SL due to all physical disorders (HR = 1.44, 95% CI = 1.22 to 1.69), cancer (HR = 1.49, 95% CI = 1.10 to 2.01), cardiovascular disease (CVD; HR = 2.16, 95% CI = 1.31 to 3.55), and injuries/external causes (HR = 1.83, 95% CI = 1.31 to 2.58). Former smokers were at a higher risk of SL due to cancer at a borderline significance level (HR = 1.38, 95% CI = 0.99 to 1.92). Low-intensity smoking (ie, 1-10 cigarettes smoked per day) was associated with all-cause SL, SL due to CVD, and SL due to injuries/external causes compared with never-smokers. CONCLUSION: In a large cohort of working-age Japanese, smoking was associated with a greater risk of long-term SL. Greater effort is needed to mitigate disease burden associated with smoking at workplace in Japan. IMPLICATIONS: Our study contributes to the literature on the association between smoking and SL in several ways. First, the study was conducted among a Japanese working population. While the association has been extensively studied in Western setting, few attempts have been made elsewhere. Second, cause-specific analyses were undertaken in our study. Third, we paid attention to the effect of low-intensity smoking on SL given that there is growing evidence of an elevated health risk associated with low-intensity smoking.

Prospective Study on the Association Between Adherence to Healthy Lifestyles and Depressive Symptoms Among Japanese Employees: The Furukawa Nutrition and Health Study.

BACKGROUND: While a growing body of research suggests a protective role of healthy lifestyle against depression, evidence from prospective studies is scarce. We constructed a healthy lifestyle index (HLI) and examined its prospective association with depressive symptoms in a Japanese working population. METHODS: Participants were 917 employees (19-68 years old) who were free from depressive symptoms at baseline in 2012-2013 and attended the 3-year follow-up survey. The HLI (range: 0-7 points) was constructed by assigning 1 point to each healthy lifestyle factor, namely, (1) normal body mass index (18.5-24.9 kg/m2), (2) non-smoking, (3) no or moderate alcohol intake (≤23 g ethanol/day), (4) adequate physical activity (≥7.5 metabolic equivalent-hours/week), (5) high vegetable intake (≥350 g/day), (6) high fruit intake (≥200 g/day), and (7) adequate sleep duration (6-8.9 hours/day), which was categorized into three groups (low: 0-2 points; middle: 3-4 points; and high: 5-7 points). Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression Scale. RESULTS: A total of 155 incident cases (17.0%) of depressive symptoms were identified at the follow-up survey. Compared with the low HLI group, multivariable-adjusted odds ratios of depressive symptoms were 0.74 (95% confidence interval, 0.48-1.15) and 0.55 (95% confidence interval, 0.31-0.99) for the middle and high HLI groups, respectively (P-trend = 0.041). CONCLUSION: The present study suggests the importance of adherence to multiple healthy lifestyle factors in prevention of depressive symptoms.

Correction to: The effect of youths as change agents on cardiovascular disease risk factors among adult neighbours: a cluster randomised controlled trial in Sri Lanka.

It was highlighted that in the original article [1] the selection process was not described clearly enough to avoid confusion under the heading of the Target of Outcomes in the Methods section.

Association of changes in commute mode with body mass index and visceral adiposity: a longitudinal study.

BACKGROUND: Prospective data are sparse for active commuting to work and body weight in Asia. We assessed the association of 5-year changes in commuting mode with body mass index (BMI) and the indicators of abdominal obesity in Japanese working adults. METHODS: In this longitudinal study, we studied 29,758 participants (25,808 men and 3950 women) in Japan aged 30 to 64 years at baseline who underwent further health examination 5 years after the baseline examination. Changes in BMI were calculated from objectively measured body height and weight at baseline and follow-up examination. Visceral and subcutaneous fat areas and waist circumference measured by computed tomography scans were used as indicators for abdominal adiposity. Linear regression was applied to estimate the association of changes in commuting mode with the obesity outcomes. RESULTS: Within the 5-year study period, adults who maintained inactive commuting gained weight, and compared with this group, adults who switched to inactive commuting had higher weight gain; conversely, adults who switched to active or public transportation commuting and especially those who maintained active or public transportation commuting experienced less weight gain. Subgroup analysis showed similar tendency across the different transitions of leisure-time exercise or occupational physical activity. For example, among adults who maintained no exercise (n = 16,087), the adjusted mean (95% confidence intervals) of the BMI change over 5 years in kg/m2 were 0.27 (0.24 to 0.30) for maintained inactive commuting group (reference), 0.34 (0.30 to 0.38) for switching to inactive commuting group (P = 0.046), 0.20 (0.18 to 0.22) for switching to active commuting or public transportation group (P = 0.001), and 0.09 (0.06 to 0.13) for maintained active commuting or public transportation group (P < 0.001). Maintained inactive commuting tended to be associated with larger gain in abdominal adiposity indicators. CONCLUSION: Switching from inactive commuting mode to more physically active commuting mode and maintaining active commuting can promote body weight control among working adults across different levels of occupational or leisure-time physical activity.

Patterns of changes in overtime working hours over 3 years and the risk for progression to type 2 diabetes in adults with pre-diabetes.

No information exists regarding the effects of working hours on glucose metabolism in adults with pre-diabetes, a high-risk group for developing diabetes. Further, longitudinal patterns in working hours and their effects on glucose metabolism have not been described previously. We investigated the association between changes in overtime working hours over 3 years and the risk for progression to type 2 diabetes among adults with pre-diabetes. We analyzed patterns of overtime working hours from 2008 to 2011 among 18,172 workers in Japan (16,474 men, aged 30 to 64 years) with pre-diabetes in 2011 (baseline) using the sub-cohort data from the Japan Epidemiology Collaboration on Occupational Health Study. Participants were followed up to March 2016. Overtime working hours per month were self-reported annually in 2008-2011 and trajectory patterns were identified using group-based trajectory modeling. Type 2 diabetes was diagnosed by fasting or random plasma glucose test, hemoglobin A1c, and history of diabetes. Multivariable-adjusted hazard ratios of incident diabetes were calculated using Cox regression. We identified 3 distinct trajectories of overtime work: persistently short, long-to-short, and persistently long. During a mean follow-up of 3.5 years, 1613 participants (8.9%) developed diabetes. Compared with persistently short overtime working hours, no material increase in diabetes risk was observed for either long-to-short working hours or persistently long working hours. After adjustment for potential confounders, this association was materially unchanged. The results suggest that among individuals with pre-diabetes, persistently long working hours over 3 years were not associated with an increased risk of developing type 2 diabetes.

Smoking, Smoking Cessation, and the Risk of Hearing Loss: Japan Epidemiology Collaboration on Occupational Health Study.

INTRODUCTION: We aimed to determine the prospective association of smoking status, smoking intensity, and smoking cessation with the risk of hearing loss in a large Japanese cohort. METHODS: The cohort study included 50195 employees, who were aged 20-64 years and free of hearing loss at baseline. Participants were followed up for a maximum of 8 years. Pure-tone audiometric testing was performed annually to identify hearing loss at 1 and 4 kHz. Cox proportional hazards regression models were used to investigate the association between smoking and hearing loss. RESULTS: During follow-up, 3532 individuals developed high-frequency hearing loss, and 1575 developed low-frequency hearing loss. The hazard ratio (HR) associated with current smokers was 1.6 (95% confidence interval [CI] = 1.5 to 1.7) and 1.2 (95% CI = 1.1 to 1.4) for high- and low-frequency hearing loss, respectively, as compared with never smokers. The risk of high- and low-frequency hearing loss increased with the number of cigarettes smoked per day (both p for trend <.001). The HR associated with former smokers was 1.2 (95% CI = 1.1 to 1.3) and 0.9 (95% CI = 0.8 to 1.1) for high- and low-frequency hearing loss, respectively. The analysis by quitting years showed a decline in risk of hearing loss after quitting smoking, even among those who quitted less than 5 years before baseline. CONCLUSIONS: Smoking is associated with increased risk of hearing loss, especially at the high frequency, in a dose-response manner. The excess risk of hearing loss associated with smoking disappears in a relatively short period after quitting. IMPLICATIONS: The prospective association between smoking and hearing loss has not been well studied. To the best of our knowledge, our study is the largest to date investigating the association between smoking and incident hearing loss. Our results indicate that smoking is associated with increased risk of hearing loss in a dose-response manner. Quitting smoking virtually eliminates the excess risk of hearing loss, even among quitters with short duration of cessation. These results suggest that smoking may be a causal factor for hearing loss, although further research would be required to confirm this. If so, this would emphasize the need for tobacco control to prevent or delay the development of hearing loss.

The effect of youths as change agents on cardiovascular disease risk factors among adult neighbours: a cluster randomised controlled trial in Sri Lanka.

BACKGROUND: Mobilising non-professional health workers has been successful in improving community health, but the effectiveness of an education program targeting youths in a community-based approach remains unclear. The objective of this study was to investigate the effect of an intervention with youth on cardiovascular disease risk factors of community adults. METHODS: A 12-month cluster randomised trial was conducted in a semi-urban area of Colombo in Sri Lanka. Facilitators trained youth club members aged 15-29 years to assess cardiovascular disease risk factors and take actions in the community to address relevant issues. The control group received no intervention. Body weight and blood pressure as primary outcomes and lifestyle of adults as secondary outcomes were measured pre- and post-intervention. Multilevel linear and logistic regressions were used to assess the effects of the intervention on changes in continuous and binary outcomes, respectively, from baseline to endpoint. RESULTS: Of 512 participants at baseline, 483 completed the final assessment after the intervention. Regarding primary outcomes, the intervention group showed a significantly greater decrease in body weight after intervention than the control group. The mean (95% confidence interval) difference of body weight change for intervention versus control group was - 2.83 kg (- 3.31, - 2.35). There was no statistically significant difference in blood pressure between the two groups. Turning to the secondary outcomes, in diet, the intervention group had a higher probability of consuming at least one serving/day of fruits (p = 0.02) and a lower probability of consuming snacks twice/day or more (p < 0.001) than the control group. CONCLUSIONS: An intervention employing youths as change agents was effective in lowering body weight among community adults in Sri Lanka. TRIAL REGISTRATION: Trial registration number: SLCTR/2017/002 , Name of registry: Sri Lanka Clinical Trials Registry, Date of registration: 19th January 2017, Date of enrolment of the first participant to the trial: 1st February 2017.

Serum cholesterol levels preceding to suicide death in Japanese workers: a nested case-control study.

OBJECTIVE: To investigate the association between suicide death and serum cholesterol levels as measured at times close to suicide death. METHODS: We conducted a nested case-control study of 41 cases of suicide deaths and 205 matched controls with serum total cholesterol (TC) levels till 3 years before suicide death in a large cohort of Japanese workers. RESULTS: Individuals in the lowest versus highest tertile/predefined category of TC in a Japanese working population had a three- to four-fold greater risk of suicide death. Each 10 mg/dl decrement of average TC was associated with an 18% increased chance of suicide death (95% confidence interval, 2-35%). Similar results were found for TC levels at each year. CONCLUSION: These results suggest that a low serum TC level in recent past is associated with an increased risk of suicide death.

Metabolic Syndrome Over 4 Years Before the Onset of Cardiovascular Disease　- Nested Case-Control Study.

BACKGROUND: We investigated the risk of cardiovascular disease (CVD) with duration of metabolic syndrome (MetS) for the past 4 years before the CVD event.Methods and Results:We performed a nested case-control study within the Japan Epidemiology Collaboration on Occupational Health Study. A total of 139 registered cases of CVD and 561 self-reported cases of CVD were identified and matched individually on age, sex, and worksite with 695 and 2,803 controls, respectively. MetS was defined by the Joint Interim Statement definition. The odds ratio (95% confidence interval) for registered CVD was 4.7 (2.9, 7.5) for people with persistent MetS (positive for MetS for ≥3 assessments) and 1.9 (1.1, 3.3) for those with intermittent MetS (positive for MetS for 1-2 assessments), compared with people without MetS during the past 4 years before the event/index date (P for trend <0.001). The corresponding odds ratio for self-reported CVD was 2.7 (2.2, 3.5) and 1.8 (1.4, 2.3) (P for trend <0.001). The association with MetS duration was stronger for myocardial infarction than for other CVD subtypes. Similar results were obtained when using the Japanese MetS criteria. CONCLUSIONS: The risk of CVD increases with increasing MetS duration. These findings contribute to risk stratification and encourage lifestyle modification for people with MetS to minimize their health risk.

Smoking, Smoking Cessation, and Risk of Mortality in a Japanese Working Population　- Japan Epidemiology Collaboration on Occupational Health Study.

BACKGROUND: The effect of smoking on mortality in working-age adults remains unclear. Accordingly, we compared the effects of cigarette smoking and smoking cessation on total and cause-specific mortality in a Japanese working population. Methods and Results: This study included 79,114 Japanese workers aged 20-85 years who participated in the Japan Epidemiology Collaboration on Occupational Health Study. Deaths and causes of death were identified from death certificates, sick leave documents, family confirmation, and other sources. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated via Cox proportional hazards regression. During a maximum 6-year follow-up, there were 252 deaths in total. Multivariable-adjusted HRs (95% CIs) for total mortality, cardiovascular disease (CVD) mortality, and tobacco-related cancer mortality were 1.49 (1.10-2.01), 1.79 (0.99-3.24), and 1.80 (1.02-3.19), respectively, in current vs. never smokers. Among current smokers, the risks of total, tobacco-related cancer, and CVD mortality increased with increasing cigarette consumption (Ptrend<0.05 for all). Compared with never smokers, former smokers who quit <5 and ≥5 years before baseline had HRs (95% CIs) for total mortality of 1.80 (1.00-3.25) and 1.02 (0.57-1.82), respectively. CONCLUSIONS: In this cohort of workers, cigarette smoking was associated with increased risk of death from all and specific causes (including CVD and tobacco-related cancer), although these risks diminished 5 years after smoking cessation.

Intensity of Leisure-Time Exercise and Risk of Depressive Symptoms Among Japanese Workers: A Cohort Study.

BACKGROUND: Data on the effect of physical activity intensity on depression is scarce. We investigated the prospective association between intensity of leisure-time exercise and risk of depressive symptoms among Japanese workers. METHODS: The participants were 29,052 employees (24,653 men and 4,399 women) aged 20 to 64 years without psychiatric disease including depressive symptoms at health checkup in 2006-2007 and were followed up until 2014-2015. Details of leisure-time exercise were ascertained via a questionnaire. Depressive states were assessed using a 13-item questionnaire. Multivariable-adjusted hazard ratio of depressive symptoms was estimated using Cox regression analysis. RESULTS: During a mean follow-up of 5.8 years with 168,203 person-years, 6,847 workers developed depressive symptoms. Compared with workers who engaged in no exercise during leisure-time (0 MET-hours per week), hazard ratios (95% confidence intervals) associated with >0 to <7.5, 7.5 to <15.0, and ≥15.0 MET-hours of leisure-time exercise were 0.88 (0.82-0.94), 0.85 (0.76-0.94), and 0.78 (0.68-0.88) among workers who engaged in moderate-intensity exercise alone; 0.93 (0.82-1.06), 0.82 (0.68-0.98), and 0.83 (0.71-0.98) among workers who engaged in vigorous-intensity exercise alone; and 0.96 (0.80-1.15), 0.80 (0.67-0.95), and 0.76 (0.66-0.87) among workers who engaged in both moderate- and vigorous-intensity exercise with adjustment for age, sex, lifestyles, work-related and socioeconomic factors, and body mass index. Additional adjustment for baseline depression score attenuated the inverse association, especially among those who engaged in moderate-intensity exercise alone. CONCLUSIONS: The results suggest that vigorous-intensity exercise alone or vigorous-intensity combined with moderate-intensity exercise would prevent depressive symptoms among Japanese workers.

Sleep Duration Modifies the Association of Overtime Work With Risk of Developing Type 2 Diabetes: Japan Epidemiology Collaboration on Occupational Health Study.

BACKGROUND: Evidence linking working hours and the risk of type 2 diabetes mellitus (T2DM) is limited and inconsistent in Asian populations. No study has addressed the combined association of long working hours and sleep deprivation on T2DM risk. We investigated the association of baseline overtime work with T2DM risk and assessed whether sleep duration modified the effect among Japanese. METHODS: Participants were Japanese employees (28,489 men and 4,561 women) aged 30-64 years who reported overtime hours and had no history of diabetes at baseline (mostly in 2008). They were followed up until March 2014. New-onset T2DM was identified using subsequent checkup data, including measurement of fasting/random plasma glucose, glycated hemoglobin, and self-report of medical treatment. Hazard ratios (HRs) of T2DM were estimated using Cox regression analysis. The combined association of sleep duration and working hours was examined in a subgroup of workers (n = 27,590). RESULTS: During a mean follow-up period of 4.5 years, 1,975 adults developed T2DM. Overtime work was not materially associated with T2DM risk. In subgroup analysis, however, long working hours combined with insufficient sleep were associated with a significantly higher risk of T2DM (HR 1.42; 95% CI, 1.11-1.83), whereas long working hours with sufficient sleep were not (HR 0.99; 95% CI, 0.88-1.11) compared with the reference (<45 hours of overtime with sufficient sleep). CONCLUSIONS: Sleep duration modified the association of overtime work with the risk of developing T2DM. Further investigations to elucidate the long-term effect of long working hours on glucose metabolism are warranted.

Cumulative Risk of Type 2 Diabetes in a Working Population: The Japan Epidemiology Collaboration on Occupational Health Study.

BACKGROUND: We estimated the cumulative risk of type 2 diabetes from age 30 to 65 years in a large working population in Japan. METHODS: We used data from the Japan Epidemiology Collaboration on Occupational Health Study. Participants (46,065 men and 7,763 women) were aged 30-59 years, free of diabetes at baseline, and followed up for a maximum of 7 years. Incident type 2 diabetes was defined based on fasting and casual glucose, glycated hemoglobin, and current medical treatment for type 2 diabetes. We calculated the sex-specific cumulative risk of type 2 diabetes using the Practical Incidence Estimator macro, which was created to produce several estimates of disease incidence for prospective cohort studies based on a modified Kaplan-Meier method. RESULTS: During 274,349 person-years of follow-up, 3,587 individuals (3,339 men and 248 women) developed type 2 diabetes. The cumulative risk was 34.7% (95% confidence interval, 33.1-36.3%) for men and 18.6% (95% confidence interval, 15.5-21.7%) for women. In BMI-stratified analysis, obese (BMI ≥30 kg/m2) and overweight (BMI 25-29.9 kg/m2) men and women had a much higher cumulative risk of type 2 diabetes (obese: 77.3% for men and 64.8% for women; overweight: 49.1% and 35.7%, respectively) than those with BMI <25 kg/m2 (26.2% and 13.4% for men and women, respectively). CONCLUSIONS: The present data highlight the public health burden of type 2 diabetes in the working population. There is a need for effective programs for weight management and type 2 diabetes screening, especially for young obese employees, to prevent or delay the development of type 2 diabetes.

High Serum Phospholipid Dihomo-γ-Linoleic Acid Concentration and Low Δ5-Desaturase Activity Are Associated with Increased Risk of Type 2 Diabetes among Japanese Adults in the Hitachi Health Study.

Background: The association between the circulating fatty acid (FA) composition and type 2 diabetes (T2D) has been reported in Western populations, but evidence is scarce among Asian populations, including Japanese, who consume large amounts of fish.Objective: The objective of the present study was to prospectively examine the association between circulating concentrations of individual FAs and T2D incidence among Japanese adults.Methods: We conducted a nested case-control study in a cohort of 4754 employees, aged 34-69 y, who attended a comprehensive health checkup in 2008-2009 and donated blood samples for the Hitachi Health Study. During 5 y of follow-up, diabetes was identified on the basis of plasma glucose, glycated hemoglobin, and self-report. Two controls matched to each case by sex, age, and date of checkup were randomly chosen by using density sampling, resulting in 336 cases and 678 controls with FA measurements. GC was used to measure the FA composition in serum phospholipids. Cox proportional hazards regression was used to estimate the HRs and 95% CIs after adjusting for potential confounders. We examined the association of T2D risk with 25 different individual and combinations of FAs.Results: T2D risk was positively associated with serum dihomo-γ-linoleic acid concentration (highest compared with the lowest quartile-HR: 1.49; 95% CI: 1.04, 2.11; P-trend = 0.02) and inversely associated with Δ5-desaturase activity (highest compared with the lowest quartile-HR: 0.72; 95% CI: 0.52, 0.99; P-trend = 0.02), independent of body mass index (BMI). There were also inverse associations between T2D risk with serum total n-6 (ω-6) polyunsaturated fatty acids (PUFAs), linoleic acid, and cis-vaccenic acid, but these were attenuated and became nonsignificant after adjustment for BMI. Serum n-3 (ω-3) PUFAs and saturated fatty acids (SFAs) were not associated with T2D risk.Conclusions: T2D risk was associated with circulating concentrations of the n-6 PUFA dihomo-γ-linoleic acid and Δ5-desaturase activity but not with n-3 PUFA or SFA concentrations in Japanese adults.