Validity and reproducibility of self-reported working hours among Japanese male employees

The associations of long working hours and unhealthy diet with cardiometabolic outcomes and mortality in US workers

OBJECTIVES

To examine independent and joint associations of long working hours (LWH) and EAT-Lancet diet with cardiometabolic outcomes and mortality in US workers.

METHODS

This prospective cohort included US workers from the National Health and Nutrition Examination Survey, with cross-sectional baseline data from 1999 to March 2020. A subsample of participants from 1999 to 2018 was linked to the National Death Index, with mortality follow-up through December 2019. The independent and joint associations of LWH (≥ 55 vs. < 55 h/week) and EAT-Lancet diet scores (low vs. high) with cardiometabolic outcomes and mortality were estimated using multivariable logistic and Cox proportional hazards models, respectively.

RESULTS

LWH was associated with higher odds of obesity (OR = 1.20; 95%CI = 1.07, 1.34) among all workers and higher CVD mortality among workers with high CVD risk at baseline (HR = 1.64, 95%CI = 0.79, 3.12). Low diet scores were associated with higher odds of obesity (OR = 1.34, 95%CI = 1.21, 1.42) and diabetes (OR = 1.33, 95%CI = 1.01, 1.76) among all workers. Working hours and diet scores were jointly associated with obesity and CVD mortality, indicating by the relative excess risk due to interaction greater than zero among all workers.

CONCLUSIONS

LWH and unhealthy diet are independent risk factors and may interact to exacerbate adverse cardiometabolic health outcomes.

Association of long working hours with visceral adiposity index, anthropometric indices, and weight management behaviors: a study of Korean workers

BACKGROUND

Long working hours constitute a significant public health risk. They may induce psychological stress or lead to behavioral changes, which, in turn, can contribute to the development of cardiovascular diseases and metabolic disorders. This study investigated the association of working hours with visceral adiposity index, anthropometric indices, and weight management behaviors.

METHODS

In total, 32 373 adult workers were included in this cross-sectional study. Chinese Visceral Adiposity Index (CVAI), body mass index (BMI), waist circumference (WC), waist-to-height ratio (WHtR), and body roundness index (BRI) were assessed. Weight management behaviors over the past year, including exercise, diet control, and medication use, were self-reported. Linear or logistic regression analyses were performed. Regression models were adjusted for sex, age, education level, income level, marital status, occupation type, and survey year.

RESULTS

Among the sample, 19.4% of adults worked for ≥ 55 h per week. Compared to working 35-40 h per week, working ≥ 55 h per week was associated with higher values of 2.57 (95% confidence interval [CI:] 0.95, 4.19) in CVAI, 0.29 (95% CI: 0.14, 0.43) in BMI, 0.67 (95% CI: 0.29, 1.06) in WC, 0.47 (95% CI: 0.24, 0.69) in WHtR, and 0.09 (95% CI: 0.05, 0.14) in BRI, respectively. Working ≥ 55 h per week, in comparison with working 35-40 h per week, was linked to reduced odds of engaging in exercise for weight management (odds ratio: 0.76; 95% CI: 0.70, 0.83).

CONCLUSIONS

Working hours are positively associated with CVAI, anthropometric indices, and a lower intention to engage in exercise for weight management.

Long working hours and cardiovascular disease mortality: Prospective evidence from the United States

AIMS

Cardiovascular disease (CVD) is the leading cause of death in the United States (U.S.). This study aimed to explore prospective associations between long working hours with CVD mortality using a large, national study in the U.S.

METHODS

Data from the Midlife in the U.S. (MIDUS) Study were used, including 4051 currently employed participants without prior experience of myocardial infarction or stroke at baseline in 1995-1996. Working hours were categorized into: <35 h/week, 35-40 h/week (reference), 41-48 h/week, 49-54 h/week, and ≥ 55 h/week. Mortality data were extracted from the National Death Index (NDI) through Spring 2021. Cox proportional hazards regression was applied to analyze the prospective associations between working hours at baseline and CVD mortality, adjusting for sociodemographic and lifestyle factors. Stratified analyses by socioeconomic status (i.e., education and financial situation) were also conducted.

RESULTS

Long working hours (≥55 h/week) were significantly associated with increased CVD mortality (adjusted HR 1.50; 95 % CI 1.03-2.17) compared to the reference group. Subgroup analyses showed that individuals with low education level or poor financial situation had a higher risk of CVD mortality when working long hours.

CONCLUSION

Long working hours are a significant risk factor for CVD mortality in this national sample of U.S. workers, and participants with low socioeconomic status are more vulnerable to the effects of long working hours on CVD deaths. These findings highlight the need for considering working hour interventions in public health strategies to improve cardiovascular health outcomes in the workforce.

Validity of self-reported male sexual function scales in a young Chinese population: a comparative study with clinician-assisted evaluation

Psychometric scales, commonly used to gauge sexual function, can sometimes be influenced by response biases. In our research from June 2020 to April 2021, we examined the accuracy of self-reported sexual function scales. We invited patients from the Department of Infertility and Sexual Medicine at the Third Affiliated Hospital of Sun Yat-sen University (Guangzhou, China), who have male sexual dysfunction, to participate by filling out a self-reported version of a specific questionnaire. In addition, they went through a clinician-assisted version of this questionnaire, encompassing tools such as the Premature Ejaculation Diagnostic Tool (PEDT), the 6-item International Index of Erectile Function (IIEF-6), the Erection Hardness Scale (EHS), and the Masturbation Erection Index (MEI). Using the clinician-assisted version as a reference, we categorized patients and applied various statistical methods, such as the Chi-square test, intraclass correlation coefficient (ICC), logistic regression, and the Bland-Altman plot, to gauge reliability. In our study with 322 participants, we found that while there were no notable discrepancies in error rates based on our categorization, certain scales showed significant differences in terms of overestimation and underestimation, with the exception of the PEDT. The positive diagnosis rate consistency between the self-reported and clinician-assisted versions was observed. High ICC values between the two versions across the scales were indicative of remarkable reliability. Our findings show that the self-reported versions of tools such as EHS, IIEF-6, MEI, and PEDT are credible and hold clinical reliability. However, employing a dual-diagnosis approach might be more prudent to circumvent potential misdiagnoses.

Association between long working hours and engagement in preventive healthcare services in Korean workers: Findings from the Korean National Health and Nutrition Examination Survey

BACKGROUND

Engagement in preventive healthcare services is crucial for preventing diseases. We explored how working hours are associated with engagement in preventive healthcare services, with a focus on gender differences.

METHODS

This cross-sectional study used data from the 2007-2012 Korean National Health and Nutrition Examination Survey. The dependent variable was engagement in each of the five preventive healthcare services (health check-ups, influenza vaccination, and stomach, breast, and cervical cancer screenings). We estimated the prevalence ratios (PRs) and 95% confidence intervals (CIs) using robust Poisson regression.

RESULTS

The study analyzed 19,819 workers (9119 women). The adjusted PRs (95% CI) of the association between working ≥55 h per week and engagement in preventive healthcare services among men were 0.95 (0.90-1.00) for health check-ups, 0.86 (0.77-0.96) for influenza vaccination, and 0.95 (0.87-1.03) for stomach cancer screening compared to working 35-40 h per week. Among women, the adjusted PRs (95% CI) of the association between working ≥55 h per week and engagement in preventive healthcare services were 0.84 (0.78-0.91) for health check-ups, 0.82 (0.73-0.92) for influenza vaccination, and 0.88 (0.80-0.97) for stomach, 0.85 (0.78-0.94) for breast, and 0.82 (0.74-0.91) for cervical cancer screenings.

CONCLUSION

Long working hours were negatively associated with engagement in preventive healthcare services, and the association was pronounced among female workers. Efforts to promote preventive healthcare participation among individuals with long working hours are necessary, and it is essential to consider the unique vulnerabilities of women when developing such policies.

Perception of Whole Day Workload as a Mediator Between Activity Engagement and Stress in Workers with Type 1 Diabetes

Associations between various forms of activity engagement (e.g. work, leisure) and the experience of stress in workers have been widely documented. The mechanisms underlying these effects, however, are not fully understood. Our goal was to investigate if perceived whole day workload accounted for the relationships between daily frequencies of activities (i.e. work hours and leisure/rest) and daily stress. We analyzed data from 56 workers with type 1 diabetes (T1D) who completed approximately two weeks of intensive longitudinal assessments. Daily whole day workload was measured with an adapted version of the National Aeronautics and Space Administration Task Load Index (NASA-TLX). A variety of occupations were reported including lawyer, housekeeper, and teacher. In multilevel path analyses, day-to-day changes in whole day workload mediated 67% (p<.001), 61% (p<.001), 38% (p<.001), and 55% (p<.001) of the within-person relationships between stress and work hours, rest frequency, active leisure frequency, and day of week, respectively. Our results provided evidence that whole day workload perception may contribute to the processes linking daily activities with daily stress in workers with T1D. Perceived whole day workload may deserve greater attention as a possible stress intervention target, ones that perhaps ergonomists would be especially suited to address.

Study profile: protocol outline and study perspectives of the cohort by the National Institute of Occupational Safety and Health, Japan (JNIOSH cohort)

How work burden affects physical and mental health has already been studied extensively; however, many issues have remained unexamined. In 2017, we commenced a prospective cohort study of workers at companies in Japan, with a follow-up period of 5-10 years, in order to investigate the current situation of overwork-related health outcomes. From 2017 to 2020, a target population of 150,000 workers across 8 companies was identified. Of these, almost 40,000 workers agreed to participate in the baseline survey. Data on working hours, medical check-up measurements, occupational stress levels, and lifestyle habits were collected. The average age of the participants at baseline was 39.2 ± 11.7 years; 73.1% were men, and 87.7% were regular employees. The most common working hours by self-reported was 41-50 hours per week during normal season, and it increased to more than 50 hours during busy season. Furthermore, more than half of the participants reportedly experienced a form of sleep problem, and the percentage of those who experienced nonrestorative sleep was particularly high.

Association between Long Working Hours and Psychological Distress: The Effect Modification by Request to Stay Home When Sick in the Workplace during the COVID-19 Pandemic

The effect of workplace infection control measures required by the COVID-19 pandemic on the association between long working hours and psychological distress has not yet been fully revealed. This study investigated the effect of requesting to stay home when sick (RSH) on the association between long working hours and psychological distress. We conducted a cross-sectional survey in December 2020 among participants who had previously registered with a Japanese web survey company. A total of 27,036 workers completed a self-administered questionnaire which assessed usual daily overtime work hours. RSH was assessed using an original single-item scale, while psychological distress was measured with the K6 scale. After the interaction effect of overtime work hours and RSH on psychological distress was tested, we conducted stratified analyses using RSH. The statistical analysis demonstrated a significant interaction effect (p for interaction < 0.001). When we conducted stratified analyses, the odds ratios increased with longer working hours, both with and without RSH groups; however, the risk of long working hours causing psychological distress was greater in the latter group (odds ratio = 1.95 [95% confidence interval: 1.62−2.36] than in the former group (odds ratio = 1.73 [95% confidence interval: 1.55−1.93]). We found that working without RSH could strengthen the association between long working hours and psychological distress. Our findings contribute to preventing the deterioration of mental health during the COVID-19 pandemic.

Assessing Physicians' Recall Bias of Work Hours With a Mobile App: Interview and App-Recorded Data Comparison

Background

Previous studies have shown inconsistencies in the accuracy of self-reported work hours. However, accurate documentation of work hours is fundamental for the formation of labor policies. Strict work-hour policies decrease medical errors, improve patient safety, and promote physicians’ well-being.

Objective

The aim of this study was to estimate physicians’ recall bias of work hours with a mobile app, and to examine the association between the recall bias and physicians’ work hours.

Methods

We quantified recall bias by calculating the differences between the app-recorded and self-reported work hours of the previous week and the penultimate week. We recruited 18 physicians to install the “Staff Hours” app, which automatically recorded GPS-defined work hours for 2 months, contributing 1068 person-days. We examined the association between work hours and two recall bias indicators: (1) the difference between self-reported and app-recorded work hours and (2) the percentage of days for which work hours were not precisely recalled during interviews.

Results

App-recorded work hours highly correlated with self-reported counterparts (r=0.86-0.88, P<.001). Self-reported work hours were consistently significantly lower than app-recorded hours by –8.97 (SD 8.60) hours and –6.48 (SD 8.29) hours for the previous week and the penultimate week, respectively (both P<.001). The difference for the previous week was significantly correlated with work hours in the previous week (r=–0.410, P=.01), whereas the correlation of the difference with the hours in the penultimate week was not significant (r=–0.119, P=.48). The percentage of hours not recalled (38.6%) was significantly higher for the penultimate week (38.6%) than for the first week (16.0%), and the former was significantly correlated with work hours of the penultimate week (r=0.489, P=.002)

Conclusions

Our study identified the existence of recall bias of work hours, the extent to which the recall was biased, and the influence of work hours on recall bias.

Long working hours and risk of 50 health conditions and mortality outcomes: a multicohort study in four European countries

BACKGROUND

Studies on the association between long working hours and health have captured only a narrow range of outcomes (mainly cardiometabolic diseases and depression) and no outcome-wide studies on this topic are available. To achieve wider scope of potential harm, we examined long working hours as a risk factor for a wide range of disease and mortality endpoints.

METHODS

The data of this multicohort study were from two population cohorts from Finland (primary analysis, n=59 599) and nine cohorts (replication analysis, n=44 262) from Sweden, Denmark, and the UK, all part of the Individual-participant Meta-analysis in Working Populations (IPD-Work) consortium. Baseline-assessed long working hours (≥55 hours per week) were compared to standard working hours (35-40 h). Outcome measures with follow-up until age 65 years were 46 diseases that required hospital treatment or continuous pharmacotherapy, all-cause, and three cause-specific mortality endpoints, ascertained via linkage to national health and mortality registers.

FINDINGS

2747 (4·6%) participants in the primary cohorts and 3027 (6·8%) in the replication cohorts worked long hours. After adjustment for age, sex, and socioeconomic status, working long hours was associated with increased risk of cardiovascular death (hazard ratio 1·68; 95% confidence interval 1·08-2·61 in primary analysis and 1·52; 0·90-2·58 in replication analysis), infections (1·37; 1·13-1·67 and 1·45; 1·13-1·87), diabetes (1·18; 1·01-1·38 and 1·41; 0·98-2·02), injuries (1·22; 1·00-1·50 and 1·18; 0·98-1·18) and musculoskeletal disorders (1·15; 1·06-1·26 and 1·13; 1·00-1·27). Working long hours was not associated with all-cause mortality.

INTERPRETATION

Follow-up of 50 health outcomes in four European countries suggests that working long hours is associated with an elevated risk of early cardiovascular death and hospital-treated infections before age 65. Associations, albeit weak, were also observed with diabetes, musculoskeletal disorders and injuries. In these data working long hours was not related to elevated overall mortality.

FUNDING

NordForsk, the Medical Research Council, the National Institute on Aging, the Wellcome Trust, Academy of Finland, and Finnish Work Environment Fund.

The effect of exposure to long working hours on depression: A systematic review and meta-analysis from the WHO/ILO Joint Estimates of the Work-related Burden of Disease and Injury

BACKGROUND

The World Health Organization (WHO) and the International Labour Organization (ILO) are developing the WHO/ILO Joint Estimates of the Work-related Burden of Disease and Injury (WHO/ILO Joint Estimates), supported by a large number of individual experts. Evidence from previous reviews suggests that exposure to long working hours may cause depression. In this article, we present a systematic review and meta-analysis of parameters for estimating (if feasible) the number of deaths and disability-adjusted life years from depression that are attributable to exposure to long working hours, for the development of the WHO/ILO Joint Estimates.

OBJECTIVES

We aimed to systematically review and meta-analyse estimates of the effect of exposure to long working hours (three categories: 41-48, 49-54 and ≥55 h/week), compared with exposure to standard working hours (35-40 h/week), on depression (three outcomes: prevalence, incidence and mortality).

DATA SOURCES

We developed and published a protocol, applying the Navigation Guide as an organizing systematic review framework where feasible. We searched electronic academic databases for potentially relevant records from published and unpublished studies, including the WHO International Clinical Trial Registers Platform, Medline, PubMed, EMBASE, Web of Science, CISDOC and PsycInfo. We also searched grey literature databases, Internet search engines and organizational websites; hand-searched reference lists of previous systematic reviews; and consulted additional experts.

STUDY ELIGIBILITY AND CRITERIA

We included working-age (≥15 years) workers in the formal and informal economy in any WHO and/or ILO Member State but excluded children (aged <15 years) and unpaid domestic workers. We included randomized controlled trials, cohort studies, case-control studies and other non-randomized intervention studies with an estimate of the effect of exposure to long working hours (41-48, 49-54 and ≥55 h/week), compared with exposure to standard working hours (35-40 h/week), on depression (prevalence, incidence and/or mortality).

STUDY APPRAISAL AND SYNTHESIS METHODS

At least two review authors independently screened titles and abstracts against the eligibility criteria at a first stage and full texts of potentially eligible records at a second stage, followed by extraction of data from qualifying studies. Missing data were requested from principal study authors. We combined odds ratios using random-effects meta-analysis. Two or more review authors assessed the risk of bias, quality of evidence and strength of evidence, using Navigation Guide and GRADE tools and approaches adapted to this project.

RESULTS

Twenty-two studies (all cohort studies) met the inclusion criteria, comprising a total of 109,906 participants (51,324 females) in 32 countries (as one study included multiple countries) in three WHO regions (Americas, Europe and Western Pacific). The exposure was measured using self-reports in all studies, and the outcome was assessed with a clinical diagnostic interview (four studies), interview questions about diagnosis and treatment of depression (three studies) or a validated self-administered rating scale (15 studies). The outcome was defined as incident depression in all 22 studies, with first time incident depression in 21 studies and recurrence of depression in one study. We did not identify any study on prevalence of depression or on mortality from depression. For the body of evidence for the outcome incident depression, we had serious concerns for risk of bias due to selection because of incomplete outcome data (most studies assessed depression only twice, at baseline and at a later follow-up measurement, and likely have missed cases of depression that occurred after baseline but were in remission at the time of the follow-up measurement) and due to missing information on life-time prevalence of depression before baseline measurement. Compared with working 35-40 h/week, we are uncertain about the effect on acquiring (or incidence of) depression of working 41-48 h/week (pooled odds ratio (OR) 1.05, 95% confidence interval (CI) 0.86 to 1.29, 8 studies, 49,392 participants, I² 46%, low quality of evidence); 49-54 h/week (OR 1.06, 95% CI 0.93 to 1.21, 8 studies, 49,392 participants, I² 40%, low quality of evidence); and ≥ 55 h/week (OR 1.08, 95% CI 0.94 to 1.24, 17 studies, 91,142 participants, I² 46%, low quality of evidence). Subgroup analyses found no evidence for statistically significant (P < 0.05) differences by WHO region, sex, age group and socioeconomic status. Sensitivity analyses found no statistically significant differences by outcome measurement (clinical diagnostic interview [gold standard] versus other measures) and risk of bias ("high"/"probably high" ratings in any domain versus "low"/"probably low" in all domains).

CONCLUSIONS

We judged the existing bodies of evidence from human data as "inadequate evidence for harmfulness" for all three exposure categories, 41-48, 48-54 and ≥55 h/week, for depression prevalence, incidence and mortality; the available evidence is insufficient to assess effects of the exposure. Producing estimates of the burden of depression attributable to exposure to long working appears not evidence-based at this point. Instead, studies examining the association between long working hours and risk of depression are needed that address the limitations of the current evidence.

Global, regional, and national burdens of ischemic heart disease and stroke attributable to exposure to long working hours for 194 countries, 2000-2016: A systematic analysis from the WHO/ILO Joint Estimates of the Work-related Burden of Disease and Injury

BACKGROUND

World Health Organization (WHO) and International Labour Organization (ILO) systematic reviews reported sufficient evidence for higher risks of ischemic heart disease and stroke amongst people working long hours (≥55 hours/week), compared with people working standard hours (35-40 hours/week). This article presents WHO/ILO Joint Estimates of global, regional, and national exposure to long working hours, for 194 countries, and the attributable burdens of ischemic heart disease and stroke, for 183 countries, by sex and age, for 2000, 2010, and 2016.

METHODS AND FINDINGS

We calculated population-attributable fractions from estimates of the population exposed to long working hours and relative risks of exposure on the diseases from the systematic reviews. The exposed population was modelled using data from 2324 cross-sectional surveys and 1742 quarterly survey datasets. Attributable disease burdens were estimated by applying the population-attributable fractions to WHO's Global Health Estimates of total disease burdens.

RESULTS

In 2016, 488 million people (95% uncertainty range: 472-503 million), or 8.9% (8.6-9.1) of the global population, were exposed to working long hours (≥55 hours/week). An estimated 745,194 deaths (705,786-784,601) and 23.3 million disability-adjusted life years (22.2-24.4) from ischemic heart disease and stroke combined were attributable to this exposure. The population-attributable fractions for deaths were 3.7% (3.4-4.0) for ischemic heart disease and 6.9% for stroke (6.4-7.5); for disability-adjusted life years they were 5.3% (4.9-5.6) for ischemic heart disease and 9.3% (8.7-9.9) for stroke.

CONCLUSIONS

WHO and ILO estimate exposure to long working hours (≥55 hours/week) is common and causes large attributable burdens of ischemic heart disease and stroke. Protecting and promoting occupational and workers' safety and health requires interventions to reduce hazardous long working hours.

Advancing science or advancing careers? Researchers' opinions on success indicators

The way in which we assess researchers has been under the radar in the past few years. Critics argue that current research assessments focus on productivity and that they increase unhealthy pressures on scientists. Yet, the precise ways in which assessments should change is still open for debate. We circulated a survey with Flemish researchers to understand how they work, and how they would rate the relevance of specific indicators used in research assessments. We found that most researchers worked far beyond their expected working schedule. We also found that, although they spent most of their time doing research, respondents wished they could dedicate more time to it and spend less time writing grants and performing other activities such as administrative duties and meetings. When looking at success indicators, we found that indicators related to openness, transparency, quality, and innovation were perceived as highly important in advancing science, but as relatively overlooked in career advancement. Conversely, indicators which denoted of prestige and competition were generally rated as important to career advancement, but irrelevant or even detrimental in advancing science. Open comments from respondents further revealed that, although indicators which indicate openness, transparency, and quality (e.g., publishing open access, publishing negative findings, sharing data, etc.) should ultimately be valued more in research assessments, the resources and support currently in place were insufficient to allow researchers to endorse such practices. In other words, current research assessments are inadequate and ignore practices which are essential in contributing to the advancement of science. Yet, before we change the way in which researchers are being assessed, supporting infrastructures must be put in place to ensure that researchers are able to commit to the activities that may benefit the advancement of science.

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

Background

Methods

Results

Conclusion

The effect of exposure to long working hours on ischaemic heart disease: A systematic review and meta-analysis from the WHO/ILO Joint Estimates of the Work-related Burden of Disease and Injury

BACKGROUND

The World Health Organization (WHO) and the International Labour Organization (ILO) are developing Joint Estimates of the work-related burden of disease and injury (WHO/ILO Joint Estimates), with contributions from a large network of experts. Evidence from mechanistic data suggests that exposure to long working hours may cause ischaemic heart disease (IHD). In this paper, we present a systematic review and meta-analysis of parameters for estimating the number of deaths and disability-adjusted life years from IHD that are attributable to exposure to long working hours, for the development of the WHO/ILO Joint Estimates.

OBJECTIVES

We aimed to systematically review and meta-analyse estimates of the effect of exposure to long working hours (three categories: 41-48, 49-54 and ≥55 h/week), compared with exposure to standard working hours (35-40 h/week), on IHD (three outcomes: prevalence, incidence and mortality).

DATA SOURCES

We developed and published a protocol, applying the Navigation Guide as an organizing systematic review framework where feasible. We searched electronic databases for potentially relevant records from published and unpublished studies, including MEDLINE, Scopus, Web of Science, CISDOC, PsycINFO, and WHO ICTRP. We also searched grey literature databases, Internet search engines and organizational websites; hand-searched reference lists of previous systematic reviews; and consulted additional experts.

STUDY ELIGIBILITY AND CRITERIA

We included working-age (≥15 years) workers in the formal and informal economy in any WHO and/or ILO Member State but excluded children (aged < 15 years) and unpaid domestic workers. We included randomized controlled trials, cohort studies, case-control studies and other non-randomized intervention studies which contained an estimate of the effect of exposure to long working hours (41-48, 49-54 and ≥55 h/week), compared with exposure to standard working hours (35-40 h/week), on IHD (prevalence, incidence or mortality).

STUDY APPRAISAL AND SYNTHESIS METHODS

At least two review authors independently screened titles and abstracts against the eligibility criteria at a first stage and full texts of potentially eligible records at a second stage, followed by extraction of data from qualifying studies. Missing data were requested from principal study authors. We combined relative risks using random-effect meta-analysis. Two or more review authors assessed the risk of bias, quality of evidence and strength of evidence, using Navigation Guide and GRADE tools and approaches adapted to this project.

RESULTS

Thirty-seven studies (26 prospective cohort studies and 11 case-control studies) met the inclusion criteria, comprising a total of 768,751 participants (310,954 females) in 13 countries in three WHO regions (Americas, Europe and Western Pacific). The exposure was measured using self-reports in all studies, and the outcome was assessed with administrative health records (30 studies) or self-reported physician diagnosis (7 studies). The outcome was defined as incident non-fatal IHD event in 19 studies (8 cohort studies, 11 case-control studies), incident fatal IHD event in two studies (both cohort studies), and incident non-fatal or fatal ("mixed") event in 16 studies (all cohort studies). Because we judged cohort studies to have a relatively lower risk of bias, we prioritized evidence from these studies and treated evidence from case-control studies as supporting evidence. For the bodies of evidence for both outcomes with any eligible studies (i.e. IHD incidence and mortality), we did not have serious concerns for risk of bias (at least for the cohort studies). No eligible study was found on the effect of long working hours on IHD prevalence. Compared with working 35-40 h/week, we are uncertain about the effect on acquiring (or incidence of) IHD of working 41-48 h/week (relative risk (RR) 0.98, 95% confidence interval (CI) 0.91 to 1.07, 20 studies, 312,209 participants, I² 0%, low quality of evidence) and 49-54 h/week (RR 1.05, 95% CI 0.94 to 1.17, 18 studies, 308,405 participants, I² 0%, low quality of evidence). Compared with working 35-40 h/week, working ≥55 h/week may have led to a moderately, clinically meaningful increase in the risk of acquiring IHD, when followed up between one year and 20 years (RR 1.13, 95% CI 1.02 to 1.26, 22 studies, 339,680 participants, I² 5%, moderate quality of evidence). Compared with working 35-40 h/week, we are very uncertain about the effect on dying (mortality) from IHD of working 41-48 h/week (RR 0.99, 95% CI 0.88 to 1.12, 13 studies, 288,278 participants, I² 8%, low quality of evidence) and 49-54 h/week (RR 1.01, 95% CI 0.82 to 1.25, 11 studies, 284,474 participants, I² 13%, low quality of evidence). Compared with working 35-40 h/week, working ≥55 h/week may have led to a moderate, clinically meaningful increase in the risk of dying from IHD when followed up between eight and 30 years (RR 1.17, 95% CI 1.05 to 1.31, 16 studies, 726,803 participants, I² 0%, moderate quality of evidence). Subgroup analyses found no evidence for differences by WHO region and sex, but RRs were higher among persons with lower SES. Sensitivity analyses found no differences by outcome definition (exclusively non-fatal or fatal versus "mixed"), outcome measurement (health records versus self-reports) and risk of bias ("high"/"probably high" ratings in any domain versus "low"/"probably low" in all domains).

CONCLUSIONS

We judged the existing bodies of evidence for human evidence as "inadequate evidence for harmfulness" for the exposure categories 41-48 and 49-54 h/week for IHD prevalence, incidence and mortality, and for the exposure category ≥55 h/week for IHD prevalence. Evidence on exposure to working ≥55 h/week was judged as "sufficient evidence of harmfulness" for IHD incidence and mortality. Producing estimates for the burden of IHD attributable to exposure to working ≥55 h/week appears evidence-based, and the pooled effect estimates presented in this systematic review could be used as input data for the WHO/ILO Joint Estimates.

The effect of exposure to long working hours on stroke: A systematic review and meta-analysis from the WHO/ILO Joint Estimates of the Work-related Burden of Disease and Injury

BACKGROUND

The World Health Organization (WHO) and the International Labour Organization (ILO) are developing joint estimates of the work-related burden of disease and injury (WHO/ILO Joint Estimates), with contributions from a large network of individual experts. Evidence from mechanistic data and prior studies suggests that exposure to long working hours may cause stroke. In this paper, we present a systematic review and meta-analysis of parameters for estimating the number of deaths and disability-adjusted life years from stroke that are attributable to exposure to long working hours, for the development of the WHO/ILO Joint Estimates.

OBJECTIVES

We aimed to systematically review and meta-analyse estimates of the effect of exposure to long working hours (three categories: 41-48, 49-54 and ≥55 h/week), compared with exposure to standard working hours (35-40 h/week), on stroke (three outcomes: prevalence, incidence, and mortality).

DATA SOURCES

A protocol was developed and published, applying the Navigation Guide to systematic reviews as an organizing framework where feasible. We searched electronic databases for potentially relevant records from published and unpublished studies, including Ovid MEDLINE, PubMed, EMBASE, Scopus, Web of Science, CISDOC, PsycINFO, and WHO ICTRP. We also searched grey literature databases, Internet search engines, and organizational websites; hand-searched reference lists of previous systematic reviews; and consulted additional experts.

STUDY ELIGIBILITY AND CRITERIA

We included working-age (≥15 years) individuals in the formal and informal economy in any WHO and/or ILO Member State but excluded children (aged < 15 years) and unpaid domestic workers. We included randomized controlled trials, cohort studies, case-control studies and other non-randomized intervention studies with an estimate of the effect of exposure to long working hours (41-48, 49-54 and ≥55 h/week), compared with exposure to standard working hours (35-40 h/week), on stroke (prevalence, incidence or mortality).

STUDY APPRAISAL AND SYNTHESIS METHODS

At least two review authors independently screened titles and abstracts against the eligibility criteria at a first review stage and full texts of potentially eligible records at a second stage, followed by extraction of data from qualifying studies. Missing data were requested from principal study authors. We combined relative risks using random-effects meta-analysis. Two or more review authors assessed the risk of bias, quality of evidence and strength of evidence, using the Navigation Guide and GRADE tools and approaches adapted to this project.

RESULTS

Twenty-two studies (20 cohort studies, 2 case-control studies) met the inclusion criteria, comprising a total of 839,680 participants (364,616 females) in eight countries from three WHO regions (Americas, Europe, and Western Pacific). The exposure was measured using self-reports in all studies, and the outcome was assessed with administrative health records (13 studies), self-reported physician diagnosis (7 studies), direct diagnosis by a physician (1 study) or during a medical interview (1 study). The outcome was defined as an incident non-fatal stroke event in nine studies (7 cohort studies, 2 case-control studies), incident fatal stroke event in one cohort study and incident non-fatal or fatal ("mixed") event in 12 studies (all cohort studies). Cohort studies were judged to have a relatively low risk of bias; therefore, we prioritized evidence from these studies, but synthesised evidence from case-control studies as supporting evidence. For the bodies of evidence for both outcomes with any eligible studies (i.e. stroke incidence and mortality), we did not have serious concerns for risk of bias (at least for the cohort studies). Eligible studies were found on the effects of long working hours on stroke incidence and mortality, but not prevalence. Compared with working 35-40 h/week, we were uncertain about the effect on incidence of stroke due to working 41-48 h/week (relative risk (RR) 1.04, 95% confidence interval (CI) 0.94-1.14, 18 studies, 277,202 participants, I² 0%, low quality of evidence). There may have been an increased risk for acquiring stroke when working 49-54 h/week compared with 35-40 h/week (RR 1.13, 95% CI 1.00-1.28, 17 studies, 275,181participants, I² 0%, p 0.04, moderate quality of evidence). Compared with working 35-40 h/week, working ≥55 h/week may have led to a moderate, clinically meaningful increase in the risk of acquiring stroke, when followed up between one year and 20 years (RR 1.35, 95% CI 1.13 to 1.61, 7 studies, 162,644 participants, I² 3%, moderate quality of evidence). Compared with working 35-40 h/week, we were very uncertain about the effect on dying (mortality) of stroke due to working 41-48 h/week (RR 1.01, 95% CI 0.91-1.12, 12 studies, 265,937 participants, I² 0%, low quality of evidence), 49-54 h/week (RR 1.13, 95% CI 0.99-1.29, 11 studies, 256,129 participants, I² 0%, low quality of evidence) and 55 h/week (RR 1.08, 95% CI 0.89-1.31, 10 studies, 664,647 participants, I² 20%, low quality of evidence). Subgroup analyses found no evidence for differences by WHO region, age, sex, socioeconomic status and type of stroke. Sensitivity analyses found no differences by outcome definition (exclusively non-fatal or fatal versus "mixed") except for the comparison working ≥55 h/week versus 35-40 h/week for stroke incidence (p for subgroup differences: 0.05), risk of bias ("high"/"probably high" ratings in any domain versus "low"/"probably low" in all domains), effect estimate measures (risk versus hazard versus odds ratios) and comparator (exact versus approximate definition).

CONCLUSIONS

We judged the existing bodies of evidence for human evidence as "inadequate evidence for harmfulness" for all exposure categories for stroke prevalence and mortality and for exposure to 41-48 h/week for stroke incidence. Evidence on exposure to 48-54 h/week and ≥55 h/week was judged as "limited evidence for harmfulness" and "sufficient evidence for harmfulness" for stroke incidence, respectively. Producing estimates for the burden of stroke attributable to exposures to working 48-54 and ≥55 h/week appears evidence-based, and the pooled effect estimates presented in this systematic review could be used as input data for the WHO/ILO Joint Estimates. PROTOCOL IDENTIFIER: https://doi.org/10.1016/j.envint.2018.06.016.

PROSPERO REGISTRATION NUMBER

CRD42017060124.

Objective and subjective working hours and their roles on workers' health among Japanese employees

This study investigated the correlation between objective and subjective working hours (OWH and SWH, respectively) and their relation to the workers' health. The study included 6,806 workers of a Japanese company (response rate=86.6%). OWH were collected as the monthly data during fiscal year 2017 from the company record. SWH were self-reported as the weekly data during the past month in November 2017. Both OWH and SWH corresponded to the same period of one month (October 2017). Additionally, the data for the annual health checkup in fiscal year 2017 and self-reported mental health in November 2017 were collected. The results indicated that the longer OWH was related to more underestimation of SWH. The analyses of covariance adjusted for the selected variables showed that irrespective of OWH or SWH, significant relationships were found for stress responses but not for body mass index, aspartate and alanine aminotransferase, fasting blood glucose, hemoglobin A1c, high-density lipoprotein cholesterol, or triglyceride. However, significant relationships with only OWH were noted for systolic and diastolic blood pressure, low-density lipoprotein cholesterol, gamma-glutamyl transpeptidase, and positive work-related state of mind. The present findings show that SWH should be used carefully when assessing the health effects of long working hours.

Cumulative Exposure to Long Working Hours and Occurrence of Ischemic Heart Disease: Evidence From the CONSTANCES Cohort at Inception

Background

Long‐working hours (LWH) are a probable risk factor for ischemic heart diseases (IHD); however, no previous study has considered duration of exposure to LWH when addressing this topic. We aimed to determine the association between cumulative exposure to LWH and IHD while accounting for relevant confounders.

Methods and Results

In this retrospective study, we included all baseline participants from the French population‐based cohort CONSTANCES. Part‐time employees and those who reported a cardiac event in the 5 years before LWH exposure were excluded. From self‐administered questionnaires and clinical examinations, we obtained participants’ age, sex, body mass index, occupational status, smoking habits, high blood pressure, diabetes mellitus, familial history of cardiovascular disease, dyslipidemia, exposure to LWH, and its duration. We defined LWH as working for >10 hours daily for at least 50 days per year. The main outcome was reported history of IHD, ie, myocardial infarction or angina pectoris, during a clinical examination. Of 137 854 included participants, 69 774 were men. There were 1875 cases (1.36%) of IHD, and exposure to LWH was reported by 42 462 subjects (30.8%) among whom 14 474 (10.50%) reported exposure for at least 10 years. Overall, exposure to LWH for ≥10 years was associated with an increased risk of IHD, adjusted odds ratio (aOR) 1.24 (1.08–1.43), P=0.0021. In stratified analyses, this effect was not observed in women, but was significant amongst men, aOR 1.28 (1.11–1.48), P=0.0008.

Conclusions

This large population‐based study supports an association between cumulative exposure to LWH and IHD in men. Future research should consider relevant strategies for reducing LWH exposure and duration.

Long working hours and change in body weight: analysis of individual-participant data from 19 cohort studies

OBJECTIVE

To examine the relation between long working hours and change in body mass index (BMI).

METHODS

We performed random effects meta-analyses using individual-participant data from 19 cohort studies from Europe, US and Australia (n = 122,078), with a mean of 4.4-year follow-up. Working hours were measured at baseline and categorised as part time (<35 h/week), standard weekly hours (35-40 h, reference), 41-48 h, 49-54 h and ≥55 h/week (long working hours). There were four outcomes at follow-up: (1) overweight/obesity (BMI ≥ 25 kg/m2) or (2) overweight (BMI 25-29.9 kg/m2) among participants without overweight/obesity at baseline; (3) obesity (BMI ≥ 30 kg/m2) among participants with overweight at baseline, and (4) weight loss among participants with obesity at baseline.

RESULTS

Of the 61,143 participants without overweight/obesity at baseline, 20.2% had overweight/obesity at follow-up. Compared with standard weekly working hours, the age-, sex- and socioeconomic status-adjusted relative risk (RR) of overweight/obesity was 0.95 (95% CI 0.90-1.00) for part-time work, 1.07 (1.02-1.12) for 41-48 weekly working hours, 1.09 (1.03-1.16) for 49-54 h and 1.17 (1.08-1.27) for long working hours (P for trend <0.0001). The findings were similar after multivariable adjustment and in subgroup analyses. Long working hours were associated with an excess risk of shift from normal weight to overweight rather than from overweight to obesity. Long working hours were not associated with weight loss among participants with obesity.

CONCLUSIONS

This analysis of large individual-participant data suggests a small excess risk of overweight among the healthy-weight people who work long hours.

Association of overtime work hours with various stress responses in 59,021 Japanese workers: Retrospective cross-sectional study

This study aims to clarify the relationships between length of overtime work and various stress responses using large-scale cross-sectional data of Japanese workers. This study's participants are 59,021 Japanese workers in 117 companies. Data was collected by self-reporting questionnaire. The Brief Job Stress Questionnaire was used to measure stress responses on six scales (i.e. "lack of vigor", "irritability", "fatigue", "anxiety", "depression", and "somatic responses"). Length of overtime work hours were classified as 0-20, 21-30, 31-40, 41-50, 51-60, 61-70, 71-80, and >80 hours/month. Multiple linear regression analyses were used to examine the association of stress responses with overtime while adjusting all possible confounders. In result, workers with longer overtime showed significantly higher "irritability", "fatigue", "anxiety", "depression", and "somatic responses" for both genders (p-for-trend <0.001), however, length of overtime was negatively associated with "lack of vigor" among men (p-for-trend <0.001). Men with 61-80 hours of overtime showed high fatigue with high vigor at the same time. Length of overtime was linearly associated with various stress responses, except for "lack of vigor". Length of overtime shows linear associations with various psychosomatic stress responses. However, "lack of vigor" was not consistently associated with overtime. Male workers with 61-80 hours of monthly overtime were more likely to feel vigorous than workers with shorter overtime. However, potential longterm effects of such extreme overtime should not be underestimated and must be paid attention to.

Association between extremely long working hours and musculoskeletal symptoms: A nationwide survey of medical residents in South Korea

OBJECTIVES

It has been reported that South Korea ranked as one of the longest-working nations among OECD countries. This study sought to examine the association between long working hours and musculoskeletal pain among Korean medical residents.

METHODS

We analyzed a cross-sectional survey of 1,077 medical residents in South Korea. Working hours per week were categorized as follows: <60, 60-79, 80-99, and ≥100. Musculoskeletal pains (ie, upper limb, lower limb, and low back pain) over the past 3 months were categorized into three groups: no pain, pain without interfering with work, and pain interfering with work. Multinomial logistic regression was used to examine the association between long working hours and musculoskeletal pains after adjusting for covariates.

RESULTS

We found that the average working hours of medical resident was 85.6 hours per week in South Korea. Compared to the medical residents working <60 hours, those working ≥100 hours per week were more likely to have upper limb pain (PR: 1.77, 95% CI: 1.37, 2.30) interfering with work or low back pain (PR: 2.15, 95% CI: 1.51, 3.06) interfering with work, whereas no statistically significant association was observed in the analysis of lower limb pain.

CONCLUSIONS

This study suggests that extremely long working hours are associated with upper limb and low back pain interfering with their work among Korean medical residents.

[Validity and reliability of the Work-related Physical Activity Questionnaire for assessing intensity-specific physical activity and sedentary behavior in the workplace]

OBJECTIVE

We developed the Work-related Physical Activity Questionnaire (WPAQ) to measure occupational physical activity, including sedentary behavior and sedentary breaks (interruptions of prolonged sedentary behavior), during work. This study aimed to examine the WPAQ's reliability and criterion validity using an accelerometer.

METHODS

To examine criterion validity, 97 full-time factory workers (male: 89.7%) wore a triaxial accelerometer while working and completed the WPAQ. The questionnaire inquired about participants' normal work activities and the proportion of sitting, standing, walking, and heavy labor engaged in during work. In calculating time spent in each behavior, the proportion of each occupational activity was multiplied by the total minutes of work. Duration of uninterrupted sitting time was also measured. For reliability, the same questionnaire was administered twice (median test-retest interval: 9 days) to another convenient sample of 54 participants. Spearman's ρ was used to assess validity and intraclass correlation coefficients (ICCs) and Cohen's kappa with quadratic weighing were used to assess reliability.

RESULTS

The criterion validity of occupational sitting time measured by the WPAQ was moderate (Spearman's ρ for sedentary behavior: 0.69) based on comparison with accelerometer data. Significant positive correlations were found for standing (ρ = 0.66) and walking (ρ = 0.39) between the WPAQ and accelerometer data, though not for heavy labor. A moderate but significant correlation (ρ = 0.27) was found for sedentary breaks. Test-retest reliability for all items was adequate (ICC = 0.59-0.79 for occupational sedentary behavior and physical activities, and Cohen's kappa with quadratic weighting = 0.84 for sedentary breaks).

CONCLUSIONS

The WPAQ has acceptable properties for measuring workers' activities, including sedentary breaks. Reduced physical activity, increased time spent in sedentary behaviors, and fewer sedentary breaks during working time are all associated with adverse health outcomes. Though some occupational exposure to these activities might be unavoidable, the WPAQ may be a practical tool for assessing them.

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.

The role of compensation in explaining harmful effects of overtime work on self-reported heart disease: Preliminary evidence from a Germany prospective cohort study

BACKGROUND

Research evidence suggests harmful effects of overtime work on risk of heart disease. However, whether withdrawing compensation for overtime work (time-off or money) provides a relevant explanation of this association has not been explored.

METHODS

Using cohort data, we included 6345 employees from Germany (3079 men and 3266 women), and applied Poisson regression analysis to examine the prospective association of overtime work without compensation with risk of self-reported incident heart disease over 2 years.

RESULTS

Uncompensated overtime work was associated with an elevated risk of heart disease after adjustment for relevant variables (RR = 1.85, 95%CI: 1.05-3.25), compared to no overtime work. Stratified analyses indicated particularly strong effects among women and among employees with low socioeconomic position.

CONCLUSIONS

In line with the stress-theoretical model of effort-reward imbalance at work, these findings document an important role of compensation on heart disease in the frame of overtime work.

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.