Associations between depressive complaints and indicators of labour participation among older Dutch employees: a prospective cohort study.

PURPOSE: European policy measures have led to an increased net labour participation of older employees. Yet, via different routes (for instance disability schemes) employees still often leave the labour market early. Mental health may be an important factor hindering labour participation. Aims of this study are twofold: first, to examine the relationship between mental health-particularly depressive complaints-and indicators of labour participation among older employees over a 2-year follow-up period and second, to explore the impact of different work contexts when studying this relation. METHODS: A subsample of older employees (aged > 45 years; n = 1253) from the Maastricht Cohort Study was studied. Depressive complaints were assessed using the Hospital Anxiety and Depression scale. Logistic and Cox regression analyses covered 2 years of follow-up and were also stratified for relevant work-related factors. RESULTS: Employees with mild depressive complaints showed statistically significantly higher risks for poor mental workability (HR 2.60, 95% CI 1.14-5.92) and high psychological disengagement levels (HR 2.35, 95% CI 1.21-4.57) over time compared to employees without depressive complaints. Within various work contexts, for instance in which employees perform physically demanding work or have high psychological job demands, significantly stronger associations were found between depressive complaints and poor mental workability over time. CONCLUSIONS: This study shows strong longitudinal associations between depressive complaints and indicators of labour participation, also within different work contexts over time. Results provide valuable input for developing preventive measure aiming to enhance sustainable labour participation of older employees.

Prediction of long-term sickness absence among employees with depressive complaints.

INTRODUCTION: To study the properties of a screening instrument in predicting long-term sickness absence among employees with depressive complaints. METHODS: Employees at high risk of future sickness absence were selected by the screening instrument Balansmeter (BM). Depressive complaints were assessed with the depression scale of the Hospital Anxiety and Depression Scale. The total study population consisted of 7,401 employees. Sickness absence was assessed objectively and analyzed at 12 and 18 months of follow-up using company registers on certified sick leave. RESULTS: The relative risk (RR) for long-term sickness absence, for employees at high risk versus not at high risk, was 3.26 (95% CI 2.54-4.22) in men and 2.55 (1.98-3.35) in women, when the BM was applied in the total study population. The RR of long-term sickness absence of employees with depressive complaints compared with employees without depressive complaints was 3.13 (2.41-4.09) in men and 2.45 (2.00-3.00) in women. The RR of long-term sickness absence for the BM applied in employees with depressive complaints was 5.23 in men and 3.87 in women. When the BM with a cut-off point with a higher sensitivity was applied in employees with depressive complaints, the RR for long-term sickness absence was 4.88 in men and 3.80 in women. CONCLUSIONS: The screening instrument Balansmeter is able to predict long-term sickness absence within employees with depressive complaints. The total prediction of long-term sickness absence proved better in employees with depressive complaints compared with employees of a general working population.

Experience of health complaints and help seeking behavior in employees screened for depressive complaints and risk of future sickness absence.

INTRODUCTION: The aim of this study was to examine the associations between on the one hand depressive complaints and risk of future sickness absence and on the other hand experience of health complaints and help seeking behavior in the working population. METHODS: Cross-sectional data were used from employees working in the banking sector (n = 8,498). The screening instrument included measures to examine the risk of future sickness absence, depressive complaints and help seeking behavior. RESULTS: Of employees reporting health complaints, approximately 80% had already sought help for these complaints. Experience of health complaints and subsequent help seeking behavior differed between employees with mild to severe depressive complaints and employees at risk of future sickness absence. Experience of health complaints was highest in employees identified with both concepts (69%) compared with employees identified at risk of future sickness absence only (48%) and with mild to severe depressive complaints only (57%). In those employees identified with one or both concepts and who had not sought help already, intention to seek help was about 50%. CONCLUSIONS: From a screening perspective, employees who do not experience health complaints or who do not have the intention to seek help may refuse participation in early intervention. This might be a bottleneck in the implementation of preventive interventions in the occupational health setting.

[Aetiology of prolonged fatigue among workers. An overview of findings from the Maastricht Cohort Study]. / Etiologie van langdurige vermoeidheid onder werknemers. Overzicht van bevindingen uit de Maastrichtse Cohort Studie.

BACKGROUND: Considerable attention is being given to prolonged fatigue among workers because it occurs so frequently and is alleged to have serious consequences. AIM: To present an overview of the magnitude, causes and consequences of prolonged fatigue in the workplace with a view to preventing its occurrence. METHOD: On the basis of of the articles written as part of the Maastricht Cohort Study we present an overview of this study, a prospective cohort study (n=12,140) that covered a period of 4 years. results Prolonged fatigue seems to occur frequently among workers. Risk factors in the aetiology of prolonged fatigue were found in subjective and objective work-related factors, as well as in factors related to the health and private situation of the employee. CONCLUSION: The assumed multifactorial aetiology of prolonged fatigue was confirmed by means of prospective analyses in the Maastricht Cohort Study. The observed risk factors can be applied as tools for the development of effective preventive measures against prolonged fatigue.

[Course, consequences and treatment of prolonged fatigue among workers: an overview of findings from the Maastricht Cohort Study]. / Beloop, consequenties en behandeling van langdurige vermoeidheid onder werknemers. Overzicht van bevindingen uit de Maastrichtse Cohort Studie.

UNLABELLED: summary background Although prolonged fatigue is a common complaint among workers, relatively little is known about its course and consequences. AIM: To present an overview of the course, consequences and treatment of prolonged fatigue in the work force. METHOD: We present an overview of the findings from the Maastricht Cohort Study, which was a prospective cohort (n=12.140) that covered a period of 4 years. results Fatigue runs an unfavourable course. In many workers symptoms of fatigue are present for a long time, and in some workers the symptoms even develop into those of chronic fatigue syndrome. The consequences of prolonged fatigue are also serious and are manifested in various ways: sick leave, work disability, accidents, immunological effects and reduction in work participation. A brief cognitive behaviour therapy administered by general practitioners to employees with prolonged fatigue proved ineffective. CONCLUSION: The severe consequences of prolonged fatigue and the current lack of effective therapies underline the importance of preventing the development of fatigue complaints, for which the Maastricht Cohort Study may provide the basic tools.

Work-family conflict as a risk factor for sickness absence.

OBJECTIVES: (1) To study both cross-sectional and prospective relationships between work-family conflict and sickness absence from work; (2) to explore the direction of the relationships between the different types of conflict (work-home interference and home-work interference) and sickness absence; and (3) to explore gender differences in the above relationships. METHODS: Data from the Maastricht Cohort Study were used with six months of follow up (5072 men and 1015 women at T6). Work-family conflict was measured with the Survey Work-Home Interference Nijmegen (SWING). Sickness absence was assessed objectively through individual record linkage with the company registers on sickness absence. RESULTS: In the cross-sectional analyses, high levels of work-family conflict, work-home interference, and home-work interference were all associated with a higher odds of being absent at the time of completing the questionnaire, after controlling for age and long term disease. Differences in average number of absent days between cases and non-cases of work-home interference were significant for men and most pronounced in women, where the average number of absent days over six months follow up was almost four days higher in women with high versus low-medium work-home interference. CONCLUSIONS: A clear relation between work-family conflict and sickness absence was shown. Additionally, the direction of work-family conflict was associated with a different sickness absence pattern. Sickness absence should be added to the list of adverse outcomes for employees struggling to combine their work and family life.

Organizational characteristics as predictors of work disability: a prospective study among sick employees of for-profit and not-for-profit organizations.

INTRODUCTION: This article reports a prospective study that focused on the influence of organizational structure and organizational culture on the outcome of sickness absence, return to work or work disability. Former studies of determinants of work disability hardly have given attention to organizational characteristics and, if so, not following a appropriate prospective design. METHODS: The study population consisted of 455 employees of 45 for-profit and not-for-profit companies participating in the Maastricht Cohort Study on fatigue at work who were on sick leave for at least 6 weeks. Both independent variables which were type of company, size, centralization of decision making and organizational culture, and covariates, which were sex, age, educational level, fatigue, and chronic illness, were all measured before employees reported sick. The dependent variable outcome of the sickness absence, mainly return to work or work disability, was measured 15 months after reporting sick. RESULTS: Multilevel logistic regression analysis, with organizational characteristics as level 2 independent variables and demographic and health characteristics as covariates, suggested that the type of company (for-profit/private or not-for-profit/public) is predictive of the outcome of sickness absence (crude OR = 2.21; CI: 1.16-4.20), but this may be partially due to a higher proportion of fatigued and chronically ill employees in not-for-profit companies (adjusted OR = 2.09; CI: 0.93-4.37). Findings about the role of some other organizational characteristics, like organizational culture, were inconclusive. CONCLUSIONS: Organizational characteristics should next to health characteristics be included in the models of studies which aim at predicting which sick employees are at risk for work disability. To prevent work disability not-for-profit companies might be stimulated to more active return-to-work policy by charging them with the costs of it.

An epidemiological approach to study fatigue in the working population: the Maastricht Cohort Study.

In 1998, a large scale prospective cohort study of prolonged fatigue in the working population was started in the Netherlands. The ultimate goal of this Maastricht Cohort Study was to identify risk factors involved in the aetiology and natural course of prolonged fatigue in the working population and to develop preventive measures and treatments that can be used in occupational health settings. In this paper, a conceptual model for epidemiological research on prolonged fatigue is presented. This model is the basis for the Maastricht Cohort Study. Alongside the model and design, the characteristics of the study population, the prevalence and one year cumulative incidence of prolonged fatigue, as well as its relation with secondary health outcomes (psychological distress, need for recovery, and burnout) are presented. Furthermore, model, design, and the presented results are discussed.

Work schedules and fatigue: a prospective cohort study.

AIMS: (1) To describe the prevalence of fatigue among employees in different work schedules (day work, three-shift, five-shift, and irregular shift work); (2) to investigate whether different work schedules are related to increasing fatigue over time, while taking into account job title and job characteristics; and (3) to study fatigue among shift workers changing to day work. METHODS: Data from nine consecutive four-monthly self administered questionnaires from the Maastricht Cohort Study on Fatigue at work (n = 12 095) were used with 32 months of follow up. Day and shift workers were matched on job title. RESULTS: The prevalence of fatigue was 18.1% in day workers, 28.6% in three-shift, 23.7% in five-shift, and 19.1% in irregular shift workers. For three-shift and five-shift workers substantial higher fatigue levels were observed compared to day workers at baseline measurement. In the course of fatigue over the 32 months of follow up there were only small and insignificant differences between employees in different work schedules. However, among employees fatigued at baseline, fatigue levels decreased faster over time among five-shift workers compared to fatigued day workers. Shift workers changing to day work reported substantially higher fatigue levels prior to change, compared to those remaining in shift work. CONCLUSIONS: Substantial differences in fatigue existed between day and shift workers. However, as no considerable differences in the course of fatigue were found, these differences have probably developed within a limited time span after starting in a shift work job. Further, evidence was found that fatigue could be an important reason for quitting shift work and moving to day work. Finally, in the relation between work schedules and fatigue, perceived job characteristics might play an important role.

Need for recovery after work and the subsequent risk of cardiovascular disease in a working population.

BACKGROUND: A high need for recovery after work can be regarded as a short term adverse effect of working day stressors and the person's inability to cope and recover. Consequently, it might be an intermediate factor between job stressors and cardiovascular disease (CVD). AIM: To investigate, in a longitudinal study, the relation between need for recovery and subsequent CVD. METHODS: Data from the Maastricht Cohort Study of 12 140 workers were used, with 42 incident self reported CVD cases during 32 months of follow up. Cox proportional hazards analysis was used to calculate age, gender, smoking status, and educational level adjusted relative risks. RESULTS: The adjusted relative CVD risk for the second compared to the first tertile of the need for recovery score was 1.22 (95% CI: 0.49 to 3.04), and for the third compared to the first tertile was 3.16 (95% CI: 1.34 to 7.48). When need for recovery was entered as continuous score, an adjusted relative risk per SD increase of 1.54 (95% CI: 1.15 to 2.03) was found. Additional adjustment for several work related factors as job demands, did not notably change the observed relation between need for recovery and CVD. Moreover, the increased risk for subjects reporting high job demands (1.38 per SD increase; 95% CI: 1.02 to 3.92) decreased substantially after adjustment for need for recovery. CONCLUSION: The results show that need for recovery is a strong predictor of subsequent cardiovascular disease and might be an intermediate factor between job stressors and cardiovascular disease.

Fatigue as a risk factor for being injured in an occupational accident: results from the Maastricht Cohort Study.

AIMS: To determine whether fatigue and need for recovery are risk factors for being injured in an occupational accident. METHODS: These associations were investigated within the Maastricht Cohort Study of "Fatigue at Work", a prospective cohort study of employees from a wide range of companies and organisations. For 7051 employees information was available on fatigue as measured with the Checklist Individual Strength (CIS), need for recovery as measured with the VBBA, and possible confounding factors such as age, smoking, alcohol consumption, educational level, shift work, and work environment. Information on the risk factors was collected in May 1999 and January 2000, before the occurrence of the occupational accidents. The incidence of being injured in an occupational accident was inventoried over the year 2000. A total of 108 employees reported having been injured in an occupational accident in 2000. RESULTS: For the highest CIS fatigue score tertile a for age, gender, educational level, smoking, shift work, and work environment, adjusted relative risk for being injured in an occupational accident of 1.29 (95% CI: 1.03 to 2.78) was found compared to the lowest tertile, and for the highest tertile of need for recovery a relative risk of 2.28 (95% CI: 1.41 to 3.66) was found. CONCLUSIONS: Fatigue and need for recovery were found to be independent risk factors for being injured in an occupational accident. This means that in the push back of occupational accidents, fatigue, and even more importantly need for recovery, need special attention.

Health problems and psychosocial work environment as predictors of long term sickness absence in employees who visited the occupational physician and/or general practitioner in relation to work: a prospective study.

AIMS: To determine whether psychosocial work environment and indicators of health problems are prospectively related to incident long term sickness absence in employees who visited the occupational physician (OP) and/or general practitioner (GP) in relation to work. METHODS: The baseline measurement (May 1998) of the Maastricht Cohort Study, a prospective cohort study among 45 companies and organisations, was used to select employees at work who indicated having visited the OP and/or GP in relation to work. Self report questionnaires were used to measure indicators of health problems (presence of at least one long term disease, likeliness of having a mental illness, fatigue) and psychosocial work environment (job demands, decision latitude, social support, job satisfaction) as predictors of subsequent sickness absence. Sickness absence data regarding total numbers of sickness absence days were obtained from the companies and occupational health services during an 18 month period (between 1 July 1998 and 31 December 1999). Complete data were available from 1271 employees. RESULTS: After adjustment for demographics and the other predictors, presence of at least one long term disease (OR 2.36; 95% CI 1.29 to 4.29) and lower level of decision latitude (OR 1.69; 95% CI 1.22 to 2.38) were the strongest predictors for sickness absence of at least one month. A higher likelihood of having a mental illness, a higher level of fatigue, a lower level of social support at work, and low job satisfaction were also significant predictors for long term sickness absence, but their effect was less strong. CONCLUSION: In detecting employees at work but at risk for long term sickness absence, OPs and GPs should take into account not only influence of the psychosocial work environment in general and level of decision latitude in particular, but also influence of indicators of health problems, especially in the form of long term diseases.

Health and psychosocial work characteristics of employees who did or did not consult the general practitioner in relation to work.

OBJECTIVES: To examine how health problems and psychosocial work characteristics are associated with having visited or not having visited the general practitioner (GP) in relation to work. METHODS: Baseline self-reported data of the Maastricht Cohort Study about fatigue at work were used to gather information about fatigue (Checklist Individual Strength), presence of at least one long-term disease, likelihood of having a mental illness (General Health Questionnaire), and psychosocial work characteristics (psychological job demands, decision latitude and social support at work, as measured with the Job Content Questionnaire). The cohort participants indicated having visited (VISITORS) or not having visited (NON-VISITORS) the GP in relation to work. Differences between these groups were measured by multiple logistic regression analyses. RESULTS: When compared with VISITORS and taking into account the influence of sociodemographic characteristics and mutual associations between reported health problems and psychosocial work characteristics, a lower percentage of NON-VISITORS reported at least one long-term disease and NON-VISITORS presented lower levels of fatigue and psychological job demands, and higher levels of decision latitude and social support at work. CONCLUSIONS: The results of this study indicate that NON-VISITORS reported fewer health problems and a more positive perception of their work environment than VISITORS did. Interrelationships between psychosocial work characteristics and health variables should be taken into consideration when studying their associations with visiting the GP in relation to work.

Fatigue as a predictor of work disability.

The objective of this study was to assess the predictive value of fatigue for work disability on medical grounds within the framework of a large prospective cohort study. Analyses were carried out on the data of 10 927 employees with a follow up of 32 months. We found that fatigue, as measured with the Checklist Individual Strength, was a strong predictor of subsequent permanent work disability. The for age, gender, presence of a chronic medical condition, and educational level adjusted relative risks were, for the 2nd, 3rd, and 4th fatigue score quartile against the first, respectively: 2.17 (1.17-4.03), 3.30 (1.67-6.52), and 12.8 (5.14-32.1).

Differences in fatigue and psychological distress across occupations: results from the Maastricht Cohort Study of Fatigue at Work.

Differences in fatigue and psychological distress across occupations were examined among 8521 employees participating in the Maastricht Cohort Study of "Fatigue at Work." Additional information on the perceived psychosocial work environment was incorporated. A total of 131 occupations, classified according to the Netherlands Standard Classification of Occupations 1992, were studied. Results showed that occupation as a proxy index of the "objective" work environment adds little explanatory information beyond perceived measures of the work environment. Although "occupation" seems to be an easy entree for intervention, focusing on occupation exclusively to prevent, or at least reduce, fatigue and psychological distress may be inadequate. Supplementary information about the perceived work environment of the job occupant is needed to develop preventive measures on the individual level. Further research, including a longitudinal analysis, is required to elucidate the complex relation between occupation, psychosocial risk factors, and fatigue and psychological distress.

False positive outcomes and design characteristics in occupational cancer epidemiology studies.

BACKGROUND: Recently there has been considerable debate about possible false positive study outcomes. Several well-known epidemiologists have expressed their concern and the possibility that epidemiological research may loose credibility with policy makers as well as the general public. METHODS: We have identified 75 false positive studies and 150 true positive studies, all published reports and all epidemiological studies reporting results on substances or work processes generally recognized as being carcinogenic to humans. All studies were scored on a number of design characteristics and factors relating to the specificity of the research objective. These factors included type of study design, use of cancer registry data, adjustment for smoking and other factors, availability of exposure data, dose- and duration-effect relationship, magnitude of the reported relative risk, whether the study was considered a 'fishing expedition', affiliation and country of the first author. RESULTS: The strongest factor associated with the false positive or true positive study outcome was if the study had a specific a priori hypothesis. Fishing expeditions had an over threefold odds ratio of being false positive. Factors that decreased the odds ratio of a false positive outcome included observing a dose-effect relationship, adjusting for smoking and not using cancer registry data. CONCLUSION: The results of the analysis reported here clearly indicate that a study with a specific a priori study objective should be valued more highly in establishing a causal link between exposure and effect than a mere fishing expedition.

Changes in frequency of premature complexes and heart rate variability related to shift work.

OBJECTIVES: To investigate whether an increased risk of cardiovascular disease might be caused by increased arrhythmogeneity and by unfavourable changes in autonomic cardiac control the changes in the occurrence of premature complexes (PVCs) and in heart rate variability (HRV) were studied in subjects who started to work in shifts. METHODS: 1 Year changes in frequency of PVCs and HRV were measured in 49 shift workers and 22 control subjects working in daytime. All respondents were starting in a new job in integrated circuit or waste incinerator plants. RESULTS: The incidence of PVC increased significantly in shift workers over the 1 year follow up, compared with daytime workers. The frequency of ventricular extrasystoles increased in 48.9% of the shift workers, and in 27.3% of the daytime workers. The Spearman correlation coefficient between the number of nights worked and the change in PVCs was 0.33 (p=0.004). A small non-significant unfavourable change in HRV was found in both the shift and daytime workers. CONCLUSIONS: A change in arrhythmogeneity, but not in cardiac autonomic control, might explain the increased risk of cardiovascular disease in shift workers.

Occupational determinants of heart rate variability.

OBJECTIVES: Analysis of HRV has been suggested as a way to study the effects of work-related stresses on cardiovascular autonomic regulation. The aim of this study was to evaluate the use of HRV in the investigation of work-related stressors. METHODS: Cross-sectional data from an ongoing cohort study were used to analyse the relationship of the potential workplace stressors of job-strain, noise and shift work, with HRV. Mean HRV values during sleep and work were calculated in 135 24-h EKG recordings. RESULTS: Shift workers displayed significantly decreased SDNNi levels during sleep, compared with those of the daytime workers (adjusted least square mean values: 69.3 and 85.8 ms, respectively, P < 0.05). Compared with the control group reporting low job demands and high work control (mean: 73.2), we found significantly elevated %LF means during work adjusted for sleep in the low demands, low control group (77.9, P < 0.01), high demands, high control group (77.7, P < 0.05) and high demands, low control group (77.7, P < 0.05). Workers reporting a high noise level compared with a low work noise level also displayed an elevated adjusted mean %LF during work (78.0 and 75.3 respectively, P < 0.06). CONCLUSIONS: The finding of a decreased SDNNi level during sleep in shift workers compared with day workers indicated a less favourable cardiovascular autonomic regulation, which may explain in part the excess cardiovascular disease risk in shift workers. The elevated %LF during work in employees exposed to high job strain or high noise levels indicated a direct shift in the autonomic cardiac balance towards sympathetic dominance. We concluded that the analysis of HRV may provide a useful tool in the study of the physiological effects of work-related stresses.

Duration of shiftwork related to body mass index and waist to hip ratio.

OBJECTIVE: An elevated cardiovascular disease risk for shiftworkers has frequently been reported, however, the mechanism is still unknown. Changes in eating habits, in physical activity or metabolic factors could be involved. In this study we assessed the relationship between body mass index (BMI) as a possible indicator of changed eating habits or metabolic involvement and duration of shiftwork. DESIGN: Data from an ongoing cohort study among 377 shiftworkers and non-shiftworking controls, all starting in a new job were used. Anthropometric measurements were carried out at the start of the assignment. Job history was obtained by a questionnaire. RESULTS: A positive relationship was observed between BMI and waist to hip ratio (WHR) and duration of shiftwork experience, with an adjustment for age. The linear regression coefficients, with additional adjustments for sex, smoking status, physical activity and educational level were 0.12 kg/m2 per y in shiftwork for BMI (P<0.05) and 0.0016 per y in shiftwork for WHR (P<0.05). CONCLUSIONS: These results suggest a relationship between years worked in shifts with BMI and WHR for both males and females. Whether this might reflect an effect of changed dietary habits or a metabolic effect is not yet clear.

Exercise training and heart rate variability in older people.

PURPOSE: Heart rate variability (HRV), a characteristic that is potentially increased by physical activity, has been associated with incidence of cardiac events and total mortality. Since the incidence of cardiac events among older people is high and their physical activity levels and HRV are generally low, it is important to investigate whether regular physical activity can modify HRV in this age group. The purpose of the study was to investigate the effect of regular physical activity on HRV in older men and women. METHODS: In a randomized controlled trial, the effect of six months' training on HRV was investigated in a group of 51 older men and women (67.0 +/- 5.1 yr). The training group gathered three times per week for 45 min supervised training. RESULTS: At the end of the intervention period, HRV was higher primarily during the day. During daytime, the SD of all normal intervals (+6%) as well as the low frequency component (+ 15%) and the very low frequency component (+ 10%) of HRV were significantly increased (P < 0.05) as compared with the control group. Effects of training were most pronounced in subjects inactive in sports at baseline. CONCLUSION: This study demonstrates that regular physical activity increases HRV (specifically in the very low and low frequency components) in older subjects. Hence, in older subjects, physical training may be an effective means to modify positively a factor that is associated with increased incidence of cardiac events.