The association between study characteristics and outcome in the relation between job stress and cardiovascular disease - a multilevel meta-regression analysis.

OBJECTIVES: Studies about job strain and cardiovascular disease (CVD) have yielded inconsistent results, which hinders making a firm conclusion about the association. Inconsistent findings may be the result of methodological differences. If the relative CVD risk is influenced by methodological differences, these differences should be explored in more detail in future research to clarify which methodological characteristics are inherent to obtain the most accurate estimate between job strain and CVD risk. By assessing how study characteristics are associated with the outcome, we take the first step in unraveling this association. In this review, we explore the following research question: are study characteristics associated with the size of the reported relative CVD risk? METHODS: A systematic literature search yielded 71 studies about job stress, assessed with the demand-control model, and CVD. Traditional meta-regression was extended enabling the use of correlated data to quantify heterogeneity within and between studies. RESULTS: Compared to studies that use the original Job Content Questionnaire (JCQ), studies in which a more deviant form of the JCQ was used yielded, on average, 43% higher estimates. Studies conducted in the USA yielded about 26% lower estimates compared to studies conducted in Scandinavian countries. CONCLUSIONS: Several study characteristics are associated with the size of the reported relative CVD risk. Many of these study features are related to the validity of the exposure and outcome assessment and are inherent to obtain an accurate estimate between work stress and CVD risk. More research is needed to clarify why these study features impact the average relative CVD risk.

Changes in working time arrangements over time as a consequence of work-family conflict.

Existing longitudinal studies on the relationship between working time arrangements (WTA) and work-family conflict have mainly focused on the normal causal relationship, that is, the impact of WTA on work-family conflict over time. So far, however, the reversed relationship, that is, the effect of work-family conflict on adjustments in WTA over time, has hardly been studied. Because work-family conflict is highly prevalent in the working population, further insight in this reverse relationship is invaluable to gain insight into secondary selection processes. The aim of this study is to investigate whether work-family conflict is prospectively related to adjustments in work schedules, working hours, and overtime work, and to explore sex differences and different time lags in this relation. Data of the prospective Maastricht Cohort Study were used. To study the effect of work-family conflict on a change from shift- to day work over 32 months of follow-up, male three-shift (n = 727), five-shift (n = 932), and irregular-shift (n = 451) workers were selected. To study effects of work-family conflict on reduction of working hours over 12 and 24 months of follow-up, respectively, only day workers (males and females) were selected, capturing 5809 full-time workers (> or =36 h/wk) and 1387 part-time workers (<36 h/wk) at baseline. To examine effects of work-family conflict on refraining from overtime work over 12 months of follow-up, only day workers reporting frequent overtime work at baseline were selected (3145 full-time and 492 part-time workers). Cox regression analyses were performed with adjustments for age, educational level, and presence of a long-term illness. Work-family conflict was associated with a significantly increased risk of changing from shift- to day work over 32 months of follow-up in three-shift workers (relative risk [RR] = 1.77, 95% confidence interval [CI] 1.19-2.63) but not in five-shift workers (RR = 1.32, 95% CI 0.78-2.24) and irregular-shift workers (RR = 0.81, 95% CI 0.50-1.31). Within day workers, work-family conflict among full-time workers was associated with a significantly increased risk of reducing working hours during 1 yr of follow-up in women (RR = 2.80, 95% CI 1.42-5.54) but not men (RR = 1.34, 95% CI 0.81-2.22). In part-time workers, work-family conflict was associated with a significantly increased risk of reducing working hours during 1 yr of follow-up both in women (RR = 1.99, 95% CI 1.04-3.82) and men (RR = 4.03, 95% CI 1.28-12.68). Whereas the effects of work-family conflict on a reduction of working hours somewhat decreased among female full-time workers after 2 yr of follow-up (RR = 2.13, 95% CI 1.24-3.66), among male full-time workers the effects increased and reached statistical significance (RR = 1.53, 95% CI 1.05-2.21). Work-family conflict was not significantly associated with refraining from overtime work over 1 yr of follow-up. This study shows that work-family conflict has important consequences in terms of adjustments in work schedules and working hours over time, with considerable sex differences. The study thereby clearly illustrates secondary selection processes both in shift- and day workers, with significant implications for labor force participation, emphasizing the need for prevention of work-family conflict.

Depressed mood in the working population: associations with work schedules and working hours.

The impact of working time arrangements (WTA) on health has been studied extensively. Still, little is known about the interrelation between work schedules, working hours, and depressed mood. For work schedules, the underlying assumptions regarding depressed mood refer to a disturbance of social and biological rhythms, whereas for working hours, the assumptions relate to workload and work capacity. Conversely, depressed mood may urge an employee to adjust his/her work schedule and/or number of working hours/week (h/wk). The aim of this study was to assess the association between work schedule and working hours with depressed mood. Using baseline data from the Maastricht Cohort Study, depressed mood in day work was compared with depressed mood in different shiftwork schedules (n = 8843). Within day work, several categories of working h/wk were studied in association with depressed mood (n = 7217). The association between depressed mood and several aspects of overtime was assessed separately. Depressed mood was measured with a dichotomous item: "Did you feel down every day over the last two weeks?" Separate logistic regression analyses were conducted for men and women, with adjustments for potential confounders. The odds ratio (OR) for depressed mood was greater for men involved in shiftwork than for men only involved in day work (three-shift OR = 2.05 [95% confidence interval, CI 1.52-2.77]; five-shift OR = 1.34 [95% CI 1.00-1.80]; irregular-shift OR = 1.79 [95% CI 1.27-2.53]). In female employees, five-shift work was associated with a higher prevalence of depressed mood (OR = 5.96 [95% CI 2.83-12.56]). Regarding the number of working h/wk, men working <26 h/wk had a higher prevalence of depressed mood than men working 36-40 h/wk (OR = 2.73 [95% CI 1.35-5.52]). After conducting trend analyses, a significant decreasing trend was found in men, whereas an increasing trend was found in women working a high number of hours. Furthermore, a dose-response relationship was present in men regarding the number of overtime h/wk. This study showed that different work schedules and working hours are associated with depressed mood. Shiftwork was related to a higher prevalence of depressed mood than day work. The association was more pronounced for male employees. Regarding the number of working h/wk, male and female employees showed an opposite trend in depressed mood. Because of the possibility of a healthy worker effect and the possibility of a reciprocal relationship between WTA and depressed mood, the reported relation might be underestimated. This study has illustrated that occupational physicians, who deal with depressed mood among workers, should carefully consider the impact of WTA.

Fatigue and job stress as predictors for sickness absence during common infections.

The objective of this study was to investigate the effect of health and work-related factors as predictors of subsequent sickness absence when experiencing common infections (common cold, flu-like illness, and gastroenteritis). Self-administered questionnaire data were used (baseline n = 12,140). To perform the analysis, employees reporting common infections in the final questionnaire were selected. Employees reporting sickness absence due to common infections were compared with a group who stayed at work during an infection. Multivariate survival analysis revealed no significant effects of job demands, decision latitude, or job strain on absence in workers experiencing common infections. Low levels of commitment (risk [RR] 1.22; confidence interval [CI] 1.03-1.44) and low job satisfaction (RR 1.36; CI 1.13-1.164) increased the chance of being absent during a common cold. Also, having a long-standing disease (RR 1.22; CI 1.05-1.41) and fatigue (RR 1.20; CI 1.05-1.37) increased the chance of being absent during a common infection. Having an executive function decreased the chance of being absent. We conclude that absence during a common cold is partly influenced by motivational factors in work, in contrast to more severe common infections which are more health related. Insight in factors related to absenteeism are important as a start for preventive measures to reduce sickness absence.

Cancer mortality in a cohort of licensed herbicide applicators.

OBJECTIVES: In order to expand our knowledge on the possible long-term health effects of exposure to herbicides, we updated the follow-up of a cohort of 1341 licensed herbicide applicators in the Netherlands. The earlier report indicated that there might be an increased risk for multiple myeloma in this group. Although that finding was statistically significant, the result was based on a small number of cases. METHODS: We expanded the follow-up from 1 January 1988 to 1 January 2001, which added 13 years to the follow-up. We now report on the causes of death of 196 exposed workers. RESULTS: Our findings indicate that licensed herbicide applicators were at an increased risk for skin cancer mortality [standardized mortality ratio (SMR)=357.4, 95% confidence interval (CI) 115.1-827.0]. It is not clear if this excess of skin cancer should be attributed to herbicide exposure or to excess exposure to sunlight.

Common infections and the role of burnout in a Dutch working population.

OBJECTIVE: To determine if burnout is a risk factor for common cold, flu-like illness and gastroenteritis. METHODS: We conducted a prospective cohort study among 12,140 employees at baseline, using three consecutive self-administered questionnaires. The Maslach Burnout Inventory-General Survey (MBI-GS) was used to define employees with burnout complaints (Level 1) and clinical burnout (Level 2). The cross-sectional relationship between burnout and the occurrence of common infections was assessed at baseline, using logistic regression analysis. Survival analysis with Cox regression was performed to study the longitudinal relationship between burnout and the subscales of the MBI-GS as risk factors for common infections. RESULTS: For both levels of burnout, an increased incidence of common infections was found at baseline. The largest effect was found for the relationship between burnout and gastroenteritis (OR: 1.86, CI: 1.57-2.21 for Level 1 and OR: 3.59, CI: 2.09-6.17 for Level 2). The longitudinal analyses showed comparable results, although less pronounced. The largest effect was again found for gastroenteritis (RR: 1.55, CI: 1.28-1.86 for Level 1 and RR: 2.09, CI: 1.09-3.98 for Level 2). For flu-like illness and common cold, we found smaller but significant effects at Level 1, but not at Level 2. The subscale "Exhaustion" was found to be the strongest predictor for infections at both levels of burnout. CONCLUSIONS: This study provides evidence for burnout as a risk factor for common infections in a large heterogeneous population. Taking into account that burnout or its subscales are not primary etiological agents for these common infections, the observed effects are large.

Job insecurity as a risk factor for common infections and health complaints.

The aim of this study was to investigate the cross-sectional and longitudinal effect of job insecurity on common infections and health complaints. Self-administered questionnaire data from the Maastricht Cohort Study (n = 12, 140) were used. We used Generalized Estimating Equations analyses to calculate pooled odds ratios (ORs) and 95% confidence intervals. A cross-sectional relationship between job insecurity and common infections or health complaints was found. For the longitudinal relationship, the largest effect was found for flu-like illness (OR 1.39; CI = 1.22-1.57) and health complaints (OR 1.51; CI = 1.39-1.64). We additionally corrected for health behavior, the presence of a long-standing illness, and work-related demands, resulting in lower ORs. An increase in common infections or health complaints has a substantial impact on employee well-being and may result in economic consequences for the company.

Prevalence of common infections among employees in different work schedules.

This study examined the prevalence of common infections among employees in different work schedules. Self-administered questionnaire data from the Maastricht Cohort Study on "Fatigue at Work" (n = 12,140) were used. Job title was used as a matching variable between day and shift workers to control for their different work environment. We used a multilevel analysis of a two-level structure, in which the individual employees (level 1) were nested within job titles (level 2), adjusted for demographics, longstanding disease, health behavior, work-related factors, fatigue and sleep quality. Results from the multilevel analyses showed that, compared to day work, shift work was associated with a higher risk for common infections, with the highest risk in three-shift workers. Compared to day work, shift work was further associated with differences in health, health behavior, sleep, fatigue and perceived job characteristics, factors that may influence the occurrence of infections and should be taken into account in future studies as well.