Ij. Kant

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.

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.

Fatigue as a predictor of sickness absence: results from the Maastricht cohort study on fatigue at work

Objectives: To investigate whether there is a relationship between fatigue and sickness absence. Two additional hypotheses were based on the theoretical distinction between involuntary, health related absence and voluntary, attitudinal absence. In the literature, the former term is usually used to describe long term sickness absence, the latter relates to short term sickness absence. In line with this, the first additional hypothesis was that higher fatigue would correspond with a higher risk of long term, primarily health related absence. The second additional hypothesis was that higher fatigue would correspond with a higher risk of short term, primarily motivational absence. Methods: A multidimensional fatigue measure, as well as potential sociodemographic and work related confounders were assessed in the baseline questionnaire of the Maastricht cohort study on fatigue at work. Sickness absence was objectively assessed on the basis of organisational absence records and measured over the six months immediately following the baseline questionnaire. In the first, general hypothesis the effect of fatigue on time-to-onset of first sickness absence spell during follow up was investigated. For this purpose, a survival analysis was performed. The effect of fatigue on long term sickness absence was tested by a logistic regression analysis. The effect of fatigue on short term sickness absence was investigated by performing a survival analysis with time-to-onset of first short absence spell as an outcome. Results: It was found that higher fatigue decreased the time-to-onset of the first sickness absence spell. Additional analyses showed that fatigue was related to long term as well as to short term sickness absence. The effect of fatigue on the first mentioned outcome was stronger than the effect on the latter outcome. Potential confounders only weakened the effect of fatigue on long term absence. Conclusions: Fatigue was associated with short term but particularly with long term sickness absence. The relation between fatigue and future sickness absence holds when controlling for work related and sociodemographic confounders. Fatigue as measured with the Checklist Individual Strength can be used as a screening instrument to assess the likelihood of sickness absence in the short term.

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.

Psychosocial work characteristics as risk factors for being injured in an occupational accident

Learning ObjectivesIdentify demographic variables that influence the risk of being injured in an occupational accident in this prospective cohort study.Enumerate the risk factors that might be confounding variables when associating the risk of injury with psychosocial features at work.Specify those psychosocial work characteristics that correlated with the risk of occupational accidental injury after adjusting for possible confounding factors.State the implications of these findings for making changes at the work site. Abstract The aim of this study was to investigate the relationship between psychosocial work characteristics and the risk for being injured in an occupational accident. We performed this study within the framework of the Maastricht Cohort Study of Fatigue at Work, a prospective cohort study on employees (n = 7051) from a wide range of companies and organizations. One hundred eight workers reported being injured in an occupational accident for which the subject consulted a physician or physiotherapist. Adjustments were made for work environment and demographic variables. High psychologic job demands were a risk factor for being injured in an occupational accident. Low decision latitude had a crude relative risk for being injured in an occupational accident of 2.02 (95% confidence interval [CI] = 1.23–3.39). This relationship almost completely disappeared after adjustment for the confounders mentioned here. Coworker and supervisor support were inversely related to the risk of being injured in an occupational accident but did not reach statistical significance. Other psychosocial work characteristics that had a significant effect on the risk for being injured in an occupational accident were conflicts with the supervisor (relative risk [RR] = 2.49; 95% CI = 1.42–4.37) or colleagues (RR = 2.62; 95% CI = 1.58–4.35), job satisfaction (RR = 1.43; 95% CI = 1.08–1.91), and high emotional demands (RR = 2.45; 95% CI = 1.52–3.94). We conclude that after adjustment for demographic variables, fatigue, and factors that describe the type of work environment that high psychologic job demands, emotional demands, and conflicts with the supervisor and/or colleagues are risk factors for being injured in an occupational accident.

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.

Anxiety and depression in the working population using the HAD Scale Psychometrics, prevalence and relationships with psychosocial work characteristics

AbstractBackgroundThe purposes of this study were: 1) to explore the psychometric properties of the HAD Scale in the working population, 2) to determine the prevalence of anxiety and depression on two severity levels among employees, and 3) to examine whether psychosocial work–related determinants for both categories of mental health problems may differ.MethodsData were taken from 7482 employees participating in the epidemiological Maastricht Cohort Study on Fatigue at Work. Anxiety and depression were measured with the easy to administer self–report Hospital Anxiety and Depression (HAD) Scale, while several questionnaires and self–formulated questions were used to measure psychosocial work–related characteristics.ResultsA principal component analysis indicated that the HAD Scale enables measuring anxiety and depression as separate constructs among employees. On a subclinical level, prevalences of anxiety and depression were both considerable: anxiety prevalences were 8.2 % for males and 10 % for females, and depression prevalences were 7.1% for males and 6.2% for females. Regarding self–reported psychosocial work characteristics, in multivariate regression analyses partly differential cross–sectional associations were found for anxiety and depression.ConclusionsThe results indicate that subclinical anxiety and depression are considerable in the working population and provide suggestive evidence that diagnosing, preventing or managing anxiety and depression among employees may require focusing on different aspects of their psychosocial work environment.

Occupational exposure to carcinogens and risk of lung cancer: results from The Netherlands cohort study.

OBJECTIVES: To investigate risk of lung cancers associated with common established carcinogenic occupational exposures (asbestos, paint dust, polycyclic aromatic hydrocarbons, and welding fumes) in a prospective cohort study among the general population, and to estimate the proportion of lung cancer cases attributable to these occupational exposures. METHODS: A prospective cohort study on diet, other lifestyle factors, job history, and cancer risk that started in 1986 in The Netherlands on 58,279 men, aged 55-69 years. Based on information about job history obtained from a self-administered questionnaire, case by case expert assessment was carried out to assign to each study subject a cumulative probability of occupational exposure for each carcinogenic exposure. For analysis, a case-cohort approach was used, in which the person-years at risk were estimated from a randomly selected subcohort (n = 1688). After 4.3 years of follow up, 524 lung cancer cases with complete job history were available. RESULTS: After adjustment for age, each of the other occupational exposures, and for smoking habits and intake of vitamin C, beta-carotene, and retinol, significant associations were found between risk of lung cancer and cumulative probability of occupational exposure to asbestos (relative risk (RR) highest/no exposure = 3.49, 95% confidence interval (95% CI) 1.69 to 7.18, trend P < 0.01 or paint dust (RR highest/no exposure = 2.48, 95% CI 0.88 to 6.97, trend P < 0.01). The population attributable risks (PARs) for the four exposures based on the multivariately adjusted RRs for ever exposed versus never exposed workers were calculated. The PAR of lifetime occupational exposure to asbestos was calculated to be 11.6%. CONCLUSIONS: This prospective cohort study among the general population showed that occupational exposure to asbestos or paint dust is associated with higher RRs for lung cancer. This study shows that after adjustment for smoking and diet about 11.6% of the cases of lung cancer in men is attributable to lifetime occupational exposure to asbestos.

Fatigue, burnout, and chronic fatigue syndrome among employees on sick leave: do attributions make the difference?

Background: Persistent fatigue among employees, burnout, and chronic fatigue syndrome (CFS) are three fatigue conditions that share some characteristics in theory. However, these conditions have not been compared in empirical research, despite conceptual similarities. Methods: This cross sectional study aimed to investigate relations between persistent fatigue, burnout, and CFS by describing the clinical features of a sample of 151 fatigued employees on sick leave. Using validated instruments, subgroups based on research criteria for CFS and burnout within the sample of fatigued employees and a reference group of 97 diagnosed CFS patients were compared. Analyses of covariance were performed. Results: A total of 66 (43.7%) fatigued employees met research criteria for CFS (except symptom criteria) and 76 (50.3%) met research criteria for burnout. “CFS-like employees” (fatigued employees who met CFS criteria) reported stronger somatic attributions than “non-CFS-like employees”. Burnt out CFS-like employees were more depressed and distressed than CFS-like employees who were not burnt out. Burnout cases among the non-CFS-like employees had stronger psychological attributions than fatigued employees who were not burnt out. Compared to diagnosed CFS patients, CFS-like employees merely had a shorter duration of fatigue complaints. Burnt out CFS-like employees had stronger psychological attributions and were more distressed than CFS patients. Conclusions: Fatigued employees shared many important characteristics with CFS patients, regardless of burnout status, and many fatigued employees met CFS criteria and/or burnout criteria. Differences however concerned the causal attributions that were made. This raises questions about the role of causal attributions: are they modified by fatigue complaints or do they determine illness outcome?

Occupational risk factors for male bladder cancer: results from a population based case cohort study in the Netherlands.

OBJECTIVES This study was conducted to estimate risk of bladder cancer associated with occupational exposures to paint components, polycyclic aromatic hydrocarbons (PAHs), diesel exhausts, and aromatic amines among the general population in The Netherlands. METHODS A prospective cohort study was conducted among 58 279 men. In September 1986, the cohort members (55–69 years) completed a self administered questionnaire on risk factors for cancer including job history. Follow up for incident bladder cancer was established by linkage to cancer registries until December 1992. A case-cohort approach was used based on 532 cases and 1630 subcohort members. A case by case expert assessment was carried out to assign to the cases and subcohort members a cumulative probability of occupational exposure for each carcinogenic exposure. RESULTS Men in the highest tertiles of occupational exposure to paint components, PAHs, aromatic amines, and diesel exhaust had non-significantly higher age and smoking adjusted incident rate ratios (RRs) of bladder cancer than men with no exposure: 1.29 (95% confidence interval (95% CI) 0.71 to 2.33), 1.24 (95% CI 0.68 to 2.27), 1.32 (95% CI 0.41 to 4.23) and 1.21 (95% CI 0.78 to 1.88), respectively. The associations between paint components and PAHs and risk of bladder cancer were most pronounced for current smokers. Among former smokers it seemed that for cumulative probability of exposure to paint components and PAHs, men who had smoked more than 15 cigarettes a day had RRs below unity compared with men who had smoked less than 15 cigarettes a day, whereas among current smokers the opposite was found. Exposure to diesel exhaust was positively associated with risk of bladder cancer among current and former smokers who had smoked more than 15 cigarettes a day. CONCLUSIONS This study provided only marginal evidence for an association between occupational exposure to paint components, PAHs, aromatic amines, and bladder cancer. Despite the small proportion of exposed subjects, an interaction with cigarette smoking was found, specifically for paint components, suggesting that the carcinogenic effect on the bladder might decrease after stopping smoking.