Long working hours, anthropometry, lung function, blood pressure and blood-based biomarkers: cross-sectional findings from the CONSTANCES study

Systematic review and meta-analysis of the association between long working hours and hypertension risk

BACKGROUND

Hypertension, a major public health problem worldwide, has been linked to lifestyle factors and work conditions, with conflicting evidence on the association between long work hours and risk of hypertension.

METHODS

We conducted a systematic review and meta-analysis of observational studies to investigate the relationship between working hours and hypertension or blood pressure, assessed the risk of bias and performed subgroup analyses. The protocol was registered with the International Prospective Register of Systematic Reviews.

RESULTS

The pooled OR for the association between long working hours and risk of hypertension was 1.09 (95% CI: 0.88 to 1.35) in the 15 studies that used hypertension as the outcome. In the three studies that used blood pressure as the outcome, diastolic blood pressure was higher among those with long working hours compared with those with non-long working hours (1.24 mm Hg, 95% CI: 0.19 to 2.29). In subgroup analysis, the pooled OR for the association between long working hours and risk of hypertension was 1.28 (95% CI: 1.14 to 1.44) and 1.00 (95% CI: 0.64 to 1.56) in women and men, respectively.

CONCLUSIONS

Although this study could not clearly confirm the relationship between long working hours and hypertension, the subgroup analysis suggests that long working hours may be associated with hypertension, particularly among women. More reliable research is needed to establish causality.

PROSPERO REGISTRATION NUMBER

CRD42023406961.

Impact of 24 h shifts on urinary catecholamine in emergency physicians: a cross-over randomized trial

24-h shift (24 hS) exposed emergency physicians to a higher stress level than 14-h night shift (14 hS), with an impact spreading on several days. Catecholamines are supposed to be chronic stress biomarker. However, no study has used catecholamines to assess short-term residual stress or measured them over multiple shifts. A shift-randomized trial was conducted to study urinary catecholamines levels of 17 emergency physicians during a control day (clerical work on return from leave) and two working day (14 hS and 24 hS). The Wilcoxon matched-pairs test was utilized to compare the mean catecholamine levels. Additionally, a multivariable generalized estimating equations model was employed to further analyze the independent relationships between key factors such as shifts (compared to control day), perceived stress, and age with catecholamine levels. Dopamine levels were lower during 24 hS than 14 hS and the control day. Norepinephrine levels increased two-fold during both night shifts. Epinephrine levels were higher during the day period of both shifts than on the control day. Despite having a rest day, the dopamine levels did not return to their normal values by the end of the third day after the 24 hS. The generalized estimating equations model confirmed relationships of catecholamines with workload and fatigue. To conclude, urinary catecholamine biomarkers are a convenient and non-invasive strong measure of stress during night shifts, both acutely and over time. Dopamine levels are the strongest biomarker with a prolonged alteration of its circadian rhythm. Due to the relation between increased catecholamine levels and both adverse psychological effects and cardiovascular disease, we suggest that emergency physicians restrict their exposure to 24 hS to mitigate these risks.

Self-Employment, Working Hours, and Hypertension by Race/Ethnicity in the USA

There is a large literature on work-related characteristics and hypertension, but studies on self-employment, longer working hours, and hypertension are mixed. Assessments of self-employment should be extended to account for people with part-time self-employment (i.e., employees also earning income from self-employment). The aim of this study was to determine the association of different types of self-employment with hypertension among adults by race/ethnicity and to assess whether longer working hours moderated these associations. Using data from the 2007-2018 National Health and Nutrition Examination Survey, measured hypertension (blood pressure ≥ 140/90 mm Hg) was assessed and employment categories included employees, part-time self-employment (i.e., employee with self-employment income), or full-time self-employment. Modified Poisson regressions and multiplicative interaction terms were used. Having full-time self-employment was associated with lower relative risk (RR) of hypertension compared to employees among Black (RR = 0.77, 95% confidence interval (CI) = 0.61-0.96) and White men (RR = 0.77, 0.65-0.93) compared to employees. Full-time self-employment was associated with higher risk of hypertension (RR = 1.36, 95% CI = 1.01-1.82) compared to employees among Hispanic women, while part-time self-employment was associated with lower risk (RR = 0.69, 95% CI = 0.48-0.98). Among White women, part-time self-employment was associated with higher relative risk of hypertension (RR = 1.27, 95% CI = 1.05-1.53) compared to employees. There were significant interactions between employment categories and longer working hours among Hispanic women as well as Black women and men. The results suggest that self-employment categories and longer working hours impact hypertension by race/ethnicity and sex. Because the number of full-time and part-time self-employed adults has increased, the health of this particular subgroup of workers should be further addressed.

Aging on the Job? The Association Between Occupational Characteristics and Accelerated Biological Aging

OBJECTIVES

There is a common belief that demanding jobs can make workers age faster, but there is little empirical evidence linking occupational characteristics to accelerated biological aging. We examine how occupational categorizations and self-reported working conditions are associated with expanded biological age, which incorporates 22 biomarkers and captures physiologic dysregulation throughout several bodily systems.

METHODS

Data are from 1,133 participants in the Health and Retirement Study who were aged 51-60 and working for pay in the 2010 or 2012 wave and who participated in the 2016 Venous Blood Study. We estimate associations between occupational category (professional/managerial, sales/clerical, service, and manual) and self-reported working conditions (psychosocial demands, job control, heavy lifting, and working 55 or more hours per week) and expanded biological age.

RESULTS

Compared to same-age individuals working in professional or managerial positions, those working in service jobs appear 1.65 years older biologically even after adjusting for social and economic characteristics, self-reported working conditions, health insurance, and lifestyle-related risk factors. Low job control is associated with 1.40 years, heavy lifting with 2.08 years, and long working hours with 1.87 years of accelerated biological aging.

DISCUSSION

Adverse occupational characteristics held at midlife, particularly service work, low job control, heavy lifting, and long work hours, are associated with accelerated biological aging. These findings suggest that work may be important for the overall aging process beyond its associations with specific diseases or risk factors.

Qualitative study identifies life shifts and stress coping strategies in people with multiple sclerosis

Multiple sclerosis (MS) is an auto-immune disease in which the body’s immune system attacks the central nervous system. The demyelination of the nerve fibers can lead to physical, emotional, and cognitive impairments. We wanted to learn about challenges of living with the illness and how people deal with stress. 128 individuals with MS from Austria and the US participated in the qualitative interviews. We interviewed participants and coded their answers using inductive grounded theory. We asked three open-ended questions to inquire about life since being diagnosed with MS as well as about dealing with stress. Life shifts since diagnosis involved ‘experiencing limitations’ and could be categorized in ‘emotional changes’, ‘changes with work’, ‘changes in social interaction’, ‘physical changes’, ‘changes in the medical context’. For dealing with stress active (strategies and activities) and passive coping strategies (avoid/ignore) were employed. General stress reactions were expressed in areas of emotional, physical and /or lifestyle. We recommend developing interventions in three core areas for the MS population: (1) dealing with life changes and significant experiences with MS, (2) focusing on the areas where life shifts took place, (3) focusing on active coping with stress and discussing consequences of passive coping strategies.

Work-related stress and well-being in association with epigenetic age acceleration: A Northern Finland Birth Cohort 1966 Study

Recent evidence indicates consistent association of low socioeconomic status with epigenetic age acceleration, measured from DNA methylation. As work characteristics and job stressors are crucial components of socioeconomic status, we investigated their association with various measures of epigenetic age acceleration. The study population included employed and unemployed men and women (n=604) from the Northern Finland Birth Cohort 1966. We investigated the association of job strain, effort-reward imbalance and work characteristics with five biomarkers of epigenetic aging (Hannum, Horvath, PhenoAge, GrimAge, and DunedinPoAm). Our results indicate few significant associations between work stress indicators and epigenetic age acceleration, limited to a range of ±2 years, and smoking recording the highest effect on GrimAge age acceleration biomarker between current and no smokers (median difference 4.73 years (IQR 1.18, 8.41). PhenoAgeAA was associated with job strain active work (β=-1.301 95%CI -2.391, -0.212), slowing aging of less than 1.5 years, and working as white-collar slowed aging six months (GrimAgeAA β=-0.683, 95%CI -1.264, -0.102) when compared to blue collars. Association was found for working for more than 40 hours per week that increased the aging over 1.5 years, (HorvathAA β =2.058 95%CI 0.517,3.599, HannumAA β=1.567, 95%CI 0.415,2.719). The pattern of associations was different between women and men and some of the estimated effects are inconsistent with current literature. Our results provide the first evidence of association of work conditions with epigenetic aging biomarkers. However, further epidemiological research is needed to fully understand how work-related stress affects epigenetic age acceleration in men and women in different societies.

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.

Health problems associated with single, multiple, and the frequency of months of objectively measured long working hours: a cohort study by the National Institute of Occupational Safety and Health, Japan

Purpose

We aimed to examine the prospective associations of monthly working hours measured in a month, the 6-month averaged hours, and the frequency of long working hours (≥ 205 h/month) during the past 6 months with health indicators.

Methods

This study included 6,806 Japanese company workers (response rate = 86.6%). Data on the workers’ monthly attendance during the second half of fiscal year 2016 and annual health checkups in fiscal years 2016 and 2017 were collected. We evaluated the association of the above three types of monthly working hours with subsequent health checkup data in fiscal year 2017. We adjusted for the corresponding data in fiscal year 2016.

Results

Multivariate logistic regression analyses revealed significant associations between monthly working hours and workers’ systolic and diastolic blood pressure as well as aspartate aminotransferase, alanine aminotransferase, low-density lipoprotein cholesterol (LDL), and triglyceride levels. However, the associations were not consistent between months. The average monthly working hours were significantly associated with higher LDL levels for the 220–240 h/mo group (OR: 1.49, 95%CI: 1.07–2.08) and lower triglyceride levels for the < 140 h/mo group (OR: 0.15, 95%CI: 0.03–0.77), compared to the 140–180 h/mo group. The frequency of long working hours was significantly associated with higher LDL levels.

Conclusions

Working hours over several months produced various associations with health indicators compared to those measured in a single month. Our present data suggest that the effects of average or frequency of long working hours during the past 6 months are likely to appear in LDL levels.

Cross-sectional association between long working hours and liver function: the Kangbuk Samsung Health Study

OBJECTIVES

Although the effects of long working hours on liver function remain unclear, in South Korea, there is a social perception that long working hours are associated with poor liver function. Thus, long working hours have recently become a major issue. This study aimed to determine the association between long working hours and liver function, as indicated by the alanine transaminase (ALT) levels.

DESIGN

Cross-sectional study.

SETTING

Large university hospitals in Seoul and Suwon, South Korea.

PARTICIPANTS

Workers in formal employment who underwent a comprehensive health examination at the Kangbuk Samsung Hospital Total Healthcare Centre clinics in Seoul and Suwon, South Korea, between January 2011 and December 2018. Of the 386 488 participants, 212 421 met the inclusion criteria and were included in the analysis.

PRIMARY OUTCOME MEASURE

ALT elevation.

RESULTS

The participants were predominantly well-educated (86.1%), male (69.3%) and in their 30s (49.6%). In total, 13.4% of the participants presented ALT elevation (>40 IU/L). There was no significant association between working hours and ALT elevation in the general population and in the hepatitis B surface antigen (HBsAg)-negative group. Conversely, in the HBsAg-positive group, working >60 hours per week compared with 35-40 hours per week was significantly associated with ALT elevation. The association was more pronounced in those with ALT levels >80 IU/L (OR 1.94, 95% CI 1.24 to 3.01) than in those with ALT levels >40 IU/L (OR: 1.45, 95% CI 1.20 to 1.75). The p values for trend were <0.05.

CONCLUSIONS

Long working hours were associated with ALT elevation only in hepatitis B virus carriers and not in the general population. Provided that there is adherence to the legal working hours, there is no need to further restrict working hours for liver health, irrespective of HBsAg status.

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.

Long Working Hours and the Prevalence of Masked and Sustained Hypertension

Previous studies on the effect of long working hours on blood pressure have shown inconsistent results. Mixed findings could be attributable to limitations related to blood pressure measurement and the lack of consideration of masked hypertension. The objective was to determine whether individuals who work long hours have a higher prevalence of masked and sustained hypertension. Data were collected at 3-time points over 5 years from 3547 white-collar workers. Long working hours were self-reported, and blood pressure was measured using Spacelabs 90207. Workplace clinic blood pressure was defined as the mean of the first 3readings taken at rest at the workplace. Ambulatory blood pressure was defined as the mean of the next readings recorded every 15 minutes during daytime working hours. Masked hypertension was defined as clinic blood pressure < 140/90 mm Hg and ambulatory blood pressure ≥135/85 mm Hg. Sustained hypertension was defined as clinic blood pressure ≥140/90 mm Hg and ambulatory blood pressure ≥135/85 mm Hg or being treated hypertension. Long working hours were associated with the prevalence of masked hypertension (prevalence ratio 49+ =1.70 [95% CI, 1.09–2.64]), after adjustment for sociodemographics, lifestyle-related risk factors, diabetes mellitus, family history of cardiovascular disease, and job strain. The association with sustained hypertension was of a comparable magnitude (prevalence ratio 49+ =1.66 [95% CI, 1.15–2.50]). Results suggest that long working hours are an independent risk factor for masked and sustained hypertension. Workplace strategies targeting long working hours could be effective in reducing the clinical and public health burden of hypertension.

Commuting time to work and behaviour-related health: a fixed-effect analysis

Objectives

Long commuting times are linked to poor health outcomes, but the evidence is mainly cross-sectional. We examined longitudinal within-individual associations between commuting time and behaviour-related health.

Methods

Data were from the Swedish Longitudinal Occupational Survey of Health study. We selected workers who responded to a minimum of two surveys conducted every other year between 2008 and 2018. We included all study waves with self-reported commuting time (ie, the exposure, 1–5, 6–10, 11–15 or ≥15 hours/week), body mass index (based on weight and height), physical (in)activity, smoking, alcohol use and sleep problems (ie, the outcomes) (N_individuals=20 376, N_observations=46 169). We used conditional logistic regression for fixed effects analyses that controls for time-varying confounders by design. Analyses were stratified by working hours: normal (30–40 hours/week) or longer than normal (>40 hours/week) and adjusted for time dependent covariates: age, marital status, occupational position, presence of children, chronic disease, depressive symptoms, job strain and shift work.

Results

Those working >40 hours/week had higher odds of physical inactivity (OR 1.25, 95% CI 1.03 to 1.51) and sleep problems (OR 1.16, 95% CI 1.00 to 1.35) when they were commuting >5 hours/week than when they were commuting 1–5 hours/week. Among women working normal hours, longer commuting time associated with lower odds of problem drinking.

Conclusion

Our findings suggest that lengthy commuting time increases the risk of physical inactivity and sleep problems if individuals have longer than normal weekly working hours. Effects of work arrangements that decrease commuting time should be examined in relation to health behaviours.

Implementing sensor technology applications for workplace health promotion: a needs assessment among workers with physically demanding work

Background

Workers with physically demanding work may be at risk for injury, illness or other adverse health outcomes due to exposure to different occupational hazards, especially at higher age. Sensor technology applications may be useful in the workplace to unobtrusively measure and monitor work exposures and provide workers with real-time feedback or access to data on demand. Many aspects might impede the implementation of sensor technology applications in the workplace, which should be taken into consideration for a successful implementation. Moreover, needs and preferences of workers regarding the use of sensor technology applications during work performance need to be identified. Therefore, the aim of this study was to identify worker needs and preferences regarding the use of sensor technology applications in the workplace.

Methods

Four on-site focus group sessions were conducted in four different companies among workers with physically demanding work (n = 30). Semi-structured interview schedules were used to identify which work exposures should be measured, by which kind of sensor technology applications, under which (pre)conditions, how to motivate long-term use of sensor technology applications, and which type of feedback is preferred. For data analysis, a content-analysis with an inductive approach was performed.

Results

Participants mentioned that they want to use wearable sensor technology applications to measure and monitor physical job demands, occupational heat stress, noise and fatigue. Factors associated with quality, comfort and perceived ease of use were identified as potential barriers for implementation in the workplace. Long-term motivation was attributed to the ability to manage and monitor work exposures, positive feedback and data ownership. Participants indicated a need to both receive real-time feedback and access to data on demand.

Conclusions

Sensor technology applications may support workers with physically demanding work to measure and monitor their work exposures. Potential barriers for implementation such as privacy aspects and quality, comfort and perceived ease of use of sensor technology applications need to be well considered to ensure successful implementation of sensor technology applications in the workplace.

Electronic supplementary material

The online version of this article (10.1186/s12889-019-7364-2) contains supplementary material, which is available to authorized users.