Showing papers in "Occupational and Environmental Medicine in 2003"
TL;DR: It is concluded that many of the work related variables associated with high levels of psychological ill health are potentially amenable to change and shown in intervention studies that have successfully improved psychological health and reduced sickness absence.
Abstract: A literature review revealed the following: key work factors associated with psychological ill health and sickness absence in staff were long hours worked, work overload and pressure, and the effects of these on personal lives; lack of control over work; lack of participation in decision making; poor social support; and unclear management and work role. There was some evidence that sickness absence was associated with poor management style. Successful interventions that improved psychological health and levels of sickness absence used training and organisational approaches to increase participation in decision making and problem solving, increase support and feedback, and improve communication. It is concluded that many of the work related variables associated with high levels of psychological ill health are potentially amenable to change. This is shown in intervention studies that have successfully improved psychological health and reduced sickness absence.
824 citations
TL;DR: In this article, it has been shown that exposure to particulates, nitrogen dioxide and sulphur dioxide, is associated with symptoms of bronchitis and reduced lung function in children and is reversed if the family relocates to a area with lower particulate concentrations.
Abstract: Increasing concern exists over the adverse effects of air pollution on human health. Epidemiological studies have shown a clear association between cardiovascular morbidity, decreased lung function, increased hospital admissions, mortality, and airborne concentrations of photochemical and particulate pollutants. Human exposure chamber studies of specific pollutants have shown that short term exposure leads to an acute inflammatory effect on normal human airways in a small (10–20%) proportion of healthy individuals. The consequences of long term exposure to air pollution are more difficult to access but are generally believed to be much worse. Studies in both children and adults have shown that exposure to particulates, nitrogen dioxide and sulphur dioxide, are associated with symptoms of bronchitis. Moreover, exposure to particulates has been related to reduced lung function growth in children and is reversed if the family relocates to a area with lower particulate concentrations.
As with any toxic challenge the obvious solution is to remove, or at least decrease to an acceptable level, the source of trouble. In many countries, air pollution levels have fallen in recent years, while additional measures are in place in several more to decrease concentrations further. It is unlikely however, that these practical measures will completely eliminate the problem, even in the medium term. As a consequence, it has been recognised for some time that there is also a need to improve our understanding of the impact of air pollution on biological systems. For example, a better appreciation of the mechanisms underlying air pollution induced health problems would allow a more targeted approach to remove the most toxic components of air pollution, and could possibly provide a means to decrease individual sensitivity to air pollution. As a consequence of recent research undertaken in a number of different countries, using a range of different approaches, oxidative stress has …
586 citations
TL;DR: A strong association between workplace bullying and subsequent depression suggests that bullying is an aetiological factor for mental health problems and the victims of bullying also seem to be at greater risk of cardiovascular disease, but this risk may partly be attributable to overweight.
Abstract: Aims: To examine exposure to workplace bullying as a risk factor for cardiovascular disease and depression in employees.
Methods: Logistic regression models were related to prospective data from two surveys in a cohort of 5432 hospital employees (601 men and 4831 women), aged 18–63 years. Outcomes were new reports of doctor diagnosed cardiovascular disease and depression during the two year follow up among those who were free from these diseases at baseline.
Results: The prevalence of bullying was 5% in the first survey and 6% in the second survey. Two per cent reported bullying experiences in both surveys, an indication of prolonged bullying. After adjustment for sex, age, and income, the odds ratio of incident cardiovascular disease for victims of prolonged bullying compared to non-bullied employees was 2.3 (95% CI 1.2 to 4.6). A further adjustment for overweight at baseline attenuated the odds ratio to 1.6 (95% CI 0.8 to 3.5). The association between prolonged bullying and incident depression was significant, even after these adjustments (odds ratio 4.2, 95% CI 2.0 to 8.6).
Conclusions: A strong association between workplace bullying and subsequent depression suggests that bullying is an aetiological factor for mental health problems. The victims of bullying also seem to be at greater risk of cardiovascular disease, but this risk may partly be attributable to overweight.
574 citations
TL;DR: The hypothesised role for work related fatigue as a link in the causal string of events, that is assumed to exist between repeated adverse work demands and the development of work related stress reactions, (psychological) overload and, eventually, health problems, was confirmed.
Abstract: Aims: To present the available empirical evidence for the assumed position of the concept of work related fatigue as: (1) short term effect of the working day; and (2) an intermediate variable between work demands and the development of subjective health complaints and sickness absence. Methods: Results from six single occupation studies, conducted between 1996 and 2002, are presented. Work demands (working hours, decision latitude, break control/autonomy, and mental, emotional, and physical demands) were assessed through validated scales. Work related fatigue was represented and assessed by means of the need for recovery after working time scale in all studies. Subjective health complaints and duration of sickness absence were quantified with the same instruments in most studies as well. Both cross sectional studies (four) as well as prospective studies (two; up to two years follow up) were performed. Cross sectional data of 3820 workers, in total, were available. Prospective data were accessible for 1200 workers in industry and health care. Models were tested with stepwise multiple regression analyses. Results: Strong associations between work demands and need for necovery were found in different occupations. The variance explained in need for recovery by work demands, age, and (baseline) need for recovery ranged between 14% and 48% in both types of studies. The amount of explained variance by work demands, age, and (baseline) need for recovery in subjective health complaints ranged between 24% and 58% in the different occupations. The prospective data showed the prognostic value of need for recovery in relation to subjective health complaints (in terms of psychosomatic complaints, emotional exhaustion, or sleep problems) and duration of future sickness absence. Conclusions: The hypothesised role for work related fatigue as a link in the causal string of events, that is assumed to exist between repeated adverse work demands and the development of work related stress reactions, (psychological) overload and, eventually, health problems, was confirmed.
379 citations
TL;DR: Ambulance personnel are at risk to develop health symptoms due to work related stressors, and main risk factors have to do with social aspects of the work environment, in particular lack of support from the supervisor as well as colleagues and poor communication.
Abstract: Objectives: To predict symptomatology (post-traumatic distress, fatigue, and burnout) due to acute and chronic work related stressors among ambulance personnel. Methods: Data were gathered from 123 ambulance workers in The Netherlands in a longitudinal design. At two measurements they completed standardised questionnaires to assess health symptoms, such as the Impact of Event Scale, the Maslach Burnout Inventory, and the Checklist Individual Strength. Acute stressors were assessed with specific questions, and chronic work related stressors were measured with the Questionnaire on the Experience and Assessment of Work. Results: Most of the ambulance workers had been confronted with acute stressors in their work. They also reported more chronic work related stressors than a reference group. Of the participants, more than a tenth suffered from a clinical level of post-traumatic distress, a tenth reported a fatigue level that put them at high risk for sick leave and work disability and nearly a tenth of the personnel suffered from burnout. Best predictors of symptomatology at time 2 were lack of social support at work and poor communication, such as not being informed about important decisions within the organisation. Conclusions: Ambulance personnel are at risk to develop health symptoms due to work related stressors. Although, acute stressors are related to health symptoms, such as fatigue, burnout, and post-traumatic symptoms, it was not found to predict health symptoms in the long term. Main risk factors have to do with social aspects of the work environment, in particular lack of support from the supervisor as well as colleagues and poor communication. When implementing workplace interventions these social aspects need to be taken into account.
371 citations
TL;DR: This is the first longitudinal study to show that the extent to which people are treated with justice in workplaces independently predicts their health.
Abstract: Aims: To examine the association between components of organisational justice (that is, justice of decision making procedures and interpersonal treatment) and health of employees.Methods: The Poisson regression analyses of recorded all-cause sickness absences with medical certificate and the logistic regression analyses of minor psychiatric morbidity, as assessed by the General Health Questionnaire, and poor self rated health status were based on a cohort of 416 male and 3357 female employees working during 1998-2000 in 10 hospitals in Finland.Results: Low versus high justice of decision making procedures was associated with a 41% higher risk of sickness absence in men (rate ratio (RR) 1.4, 95% confidence interval (CI) 1.1 to 1.8), and a 12% higher risk in women (RR 1.1, 95% CI 1.0 to 1.2) after adjustment for baseline characteristics., The corresponding odds ratios (OR) for minor psychiatric morbidity were 1.6 (95% CI 1.0 to 2.6) in men and 1.4 (95% CI 1.2 to 1.7) in women, and for self rated health 1.4 in both sexes. In interpersonal treatment, low justice increased the risk of sickness absence (RR 1.3 (95% CI 1.0 to 1.6) and RR 1.2 (95% CI 1.2 to 1.3) in men and women respectively), and minor psychiatric morbidity (OR 1.2 in both sexes). These figures largely Persisted after control for other risk factors (for example, job control, workload, social support, and hostility) and they were replicated in initially healthy subcohorts. No evidence was found to support the hypothesis that organisational justice would represent a consequence of health (reversed causality).Conclusions: This is the first longitudinal study to show that the extent to which people are treated with justice in workplaces independently predicts their health.
370 citations
TL;DR: Results suggest that the need for recovery scale is an adequate scale, both for applications at the individual and at the group (department/organisation) level.
Abstract: The "need for recovery scale" is suggested as an operationalisation for the measurement of (early symptoms of) fatigue at work. Definition of and background on the concept of need for recovery are briefly discussed. Details about scale construction are summarised. Correlations with other relevant measurement scales on fatigue at work are presented to validate the operationalisation claim, as are early results on predictive validity. A study is presented that further investigates the measurement quality and validity of the scale. The data used in this study were collected by Occupational Health Services for 68 775 workers during the period 1996-2000. Comparing the measurement quality of subgroups (Cronbach's alpha) differing in terms of age class, sex, and education level, the general applicability of the scale was shown. The validity of the scale was studied by analysing its association with psychosocial risk factors. Multiple regression analyses of need for recovery were performed on individual and department level data, using 10 psychosocial job characteristics as independent variables. The two most important factors in the explanation of variance at the individual level were also dominant at the department level: pace and amount of work, and emotional workload. The percentage of explained variance was higher at the department level than at the individual level, and increased with department size. Results suggest that the need for recovery scale is an adequate scale, both for applications at the individual and at the group (department/organisation) level.
360 citations
TL;DR: The experimental intervention for adjustment disorders was successful in shortening sick leave duration, mainly by decreasing long term absenteeism.
Abstract: To compare an innovative activating intervention with "care as usual" (control group) for the guidance of employees on sickness leave because of an adjustment disorder. It was hypothesised that the intervention would be more effective than care as usual in lowering the intensity of symptoms, increasing psychological resources, and decreasing sickness leave duration. A prospective, cluster randomised controlled trial was carried out with 192 patients on first sickness leave for an adjustment disorder. Symptom intensity, sickness duration, and return to work rates were measured at 3 months and 12 months. Analyses were performed on an intention to treat basis. At 3 months, significantly more patients in the intervention group had returned to work compared with the control group. At 12 months all patients had returned to work, but sickness leave was shorter in the intervention group than in the control group. The experimental intervention for adjustment disorders was successful in shortening sick leave duration, mainly by decreasing long term absenteeism.
357 citations
TL;DR: Investigation of work related and individual factors as predictors for incident neck pain among office employees working with video display units (VDUs) found female sex was a strong predictor and physical exercise may prevent neck disorders among sedentary employees.
Abstract: Aims: To investigate work related and individual factors as predictors for incident neck pain among office employees working with video display units (VDUs).
Methods: Employees in three administrative units of a medium sized city in Finland (n = 515) received mailed questionnaires in the baseline survey in 1998 and in the follow up survey in 1999. Response rate for the baseline was 81% (n = 416); respondents who reported neck pain for less than eight days during the preceding 12 months were included into the study cohort as healthy subjects (n = 232). The follow up questionnaire 12 months later was completed by 78% (n = 180). Incident neck cases were those reporting neck pain for at least eight days during the preceding 12 months.
Results: The annual incidence of neck pain was 34.4% (95% CI 25.5 to 41.3). Poor physical work environment and poor placement of the keyboard increased the risk of neck pain. Among the individual factors, female sex was a strong predictor. Smoking showed a tendency for an increased risk of neck pain. There was an interaction between mental stress and physical exercise, those with higher mental stress and less physical exercise having especially high risk.
Conclusion: In the prevention of neck disorders in office work with a high frequency of VDU tasks, attention should be given to the work environment in general and to the more specific aspects of VDU workstation layout. Physical exercise may prevent neck disorders among sedentary employees.
337 citations
TL;DR: The evidence surveyed suggests that chronic levels of silica dust that do not cause disabling silicosis may cause the development of chronic bronchitis, emphysema, and/or small airways disease that can lead to airflow obstruction, even in the absence of radiologicalsilicosis.
Abstract: Occupational exposure is an important risk factor for chronic obstructive pulmonary disease (COPD), and silica dust is one of the most important occupational respiratory toxins. Epidemiological and pathological studies suggest that silica dust exposure can lead to COPD, even in the absence of radiological signs of silicosis, and that the association between cumulative silica dust exposure and airflow obstruction is independent of silicosis. Recent clinicopathological and experimental studies have contributed further towards explaining the potential mechanism through which silica can cause pathological changes that may lead to the development of COPD. In this paper we review the epidemiological and pathological evidence relevant to the development of COPD in silica dust exposed workers within the context of recent findings. The evidence surveyed suggests that chronic levels of silica dust that do not cause disabling silicosis may cause the development of chronic bronchitis, emphysema, and/or small airways disease that can lead to airflow obstruction, even in the absence of radiological silicosis.
311 citations
TL;DR: The authors recommend the “exhaustion + 1” criterion, which can be considered as burnt out when they report, compared to a norm group, high emotional exhaustion, in combination with high depersonalisation or low personal accomplishment, for research in non-clinical populations.
Abstract: When conducting research on burnout, it may be difficult to decide whether one should report results separately for each burnout dimension or whether one should combine the dimensions. Although the multidimensionality of the burnout concept is widely acknowledged, for research purposes it is sometimes convenient to regard burnout as a unidimensional construct. This article deals with the question of whether and when it may be appropriate to treat burnout as a unidimensional variable, and presents a decision rule to distinguish between people high and low in burnout. To develop a guideline for obtaining a dichotomous measure of burnout, the scores on the Utrecht Burnout Scale (UBOS) of 44 well functioning individuals were compared with the scores of 29 individuals diagnosed as suffering from burnout. Based on these data, the authors recommend the "exhaustion + 1" criterion for research in non-clinical populations. Following this criterion, individuals can be considered as burnt out when they report, compared to a norm group, high emotional exhaustion, in combination with high depersonalisation or low personal accomplishment. The criterion may be used to estimate the percentage in a sample of individuals in a state of burnout.
TL;DR: In this paper, the authors evaluated a therapeutic exercise program intended to reduce pain and improve shoulder function in construction workers with shoulder musculoskeletal disorders and found that the intervention group showed significantly greater improvements in the Shoulder Rating Questionnaire (SRQ) score and shoulder satisfaction score than the control groups.
Abstract: Background: Repetitive or sustained elevated shoulder postures have been identified as a significant risk factor for occupationally related shoulder musculoskeletal disorders. Construction workers exposed to routine overhead work have high rates of shoulder pain that frequently progresses to functional loss and disability. Exercise interventions have potential for slowing this progression.
Aims: To evaluate a therapeutic exercise programme intended to reduce pain and improve shoulder function.
Methods: Construction worker volunteers were screened by history and clinical examination to test for inclusion/exclusion criteria consistent with shoulder pain and impingement syndrome. Sixty seven male symptomatic workers (mean age 49) were randomised into a treatment intervention group (n = 34) and a control group (n = 33); asymptomatic subjects (n = 25) participated as an additional control group. Subjects in the intervention group were instructed in a standardised eight week home exercise programme of five shoulder stretching and strengthening exercises. Subjects in the control groups received no intervention. Subjects returned after 8–12 weeks for follow up testing.
Results: The intervention group showed significantly greater improvements in the Shoulder Rating Questionnaire (SRQ) score and shoulder satisfaction score than the control groups. Average post-test SRQ scores for the exercise group remained below levels for asymptomatic workers. Intervention subjects also reported significantly greater reductions in pain and disability than controls.
Conclusions: Results suggest a home exercise programme can be effective in reducing symptoms and improving function in construction workers with shoulder pain.
TL;DR: Fatigue and need for recovery were found to be independent risk factors for being injured in an occupational accident, which means that in the push back of occupational accidents, fatigue, and even more importantlyneed for recovery, need special attention.
Abstract: 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.
TL;DR: Regular attendance at chlorinated pools by young children is associated with an exposure dependent increase in lung epithelium permeability and increase in the risk of developing asthma, especially in association with other risk factors.
Abstract: AIMS: To study whether exposure to nitrogen trichloride in indoor chlorinated pools may affect the respiratory epithelium of children and increase the risk of some lung diseases such as asthma. METHODS: In 226 healthy children, serum surfactant associated proteins A and B (SP-A and SP-B), 16 kDa Clara cell protein (CC16), and IgE were measured. Lung specific proteins were measured in the serum of 16 children and 13 adults before and after exposure to NCl(3) in an indoor chlorinated pool. Relations between pool attendance and asthma prevalence were studied in 1881 children. Asthma was screened with the exercise induced bronchoconstriction test (EIB). RESULTS: Pool attendance was the most consistent predictor of lung epithelium permeability. A positive dose-effect relation was found with cumulated pool attendance and serum SP-A and SP-B. Serum IgE was unrelated to pool attendance, but correlated positively with lung hyperpermeability as assessed by serum SP-B. Changes in serum levels of lung proteins were reproduced in children and adults attending an indoor pool. Serum SP-A and SP-B were already significantly increased after one hour on the pool side without swimming. Positive EIB and total asthma prevalence were significantly correlated with cumulated pool attendance indices. CONCLUSIONS: Regular attendance at chlorinated pools by young children is associated with an exposure dependent increase in lung epithelium permeability and increase in the risk of developing asthma, especially in association with other risk factors. We therefore postulate that the increasing exposure of children to chlorination products in indoor pools might be an important cause of the rising incidence of childhood asthma and allergic diseases in industrialised countries. Further epidemiological studies should be undertaken to test this hypothesis.
TL;DR: There is strong evidence that interventions predominantly based on technique training have no impact on working practices or injury rates and these could be used to form the basis of a generic intervention programme, with additional local priorities identified through the risk assessment process.
Abstract: Aims: To report, analyse, and discuss the results of a systematic review looking at intervention strategies to reduce the risk factors associated with patient handling activities. Methods: A search strategy was devised to seek out research between 1960 and 2001. Inclusion/ exclusion criteria limited the entry of papers into the review process. A checklist was selected and modified to include a wide range of study designs. Inter-rater reliability was established between six reviewers before the main review process commenced. Each paper was read by two reviewers and given a quality rating score, with any conflicts being resolved by a third reviewer. Papers were grouped by category: multifactor, single factor, and technique training based interventions. Results: A total of 2796 papers were found, of which 880 were appraised. Sixty three papers relating to interventions are reported in this paper. The results are reported as summary statements with the associated evidence level (strong, moderate, limited, or poor). Conclusion: There is strong evidence that interventions predominantly based on technique training have no impact on working practices or injury rates. Multifactor interventions, based on a risk assessment programme, are most likely to be successful in reducing risk factors related to patient handling activities. The seven most commonly used strategies are identified and it is suggested that these could be used to form the basis of a generic intervention programme, with additional local priorities identified through the risk assessment process. Health care providers should review their policies and procedures in light of these findings.
TL;DR: In this paper, a large sample size (n = 3417) allowed analysis of 47 pesticides simultaneously, controlling for potential confounding by other pesticides in the model, and adjusting the estimates based on a prespecified variance to make them more stable.
Abstract: Background: An increased rate of non-Hodgkin’s lymphoma (NHL) has been repeatedly observed among farmers, but identification of specific exposures that explain this observation has proven difficult. Methods: During the 1980s, the National Cancer Institute conducted three case-control studies of NHL in the midwestern United States. These pooled data were used to examine pesticide exposures in farming as risk factors for NHL in men. The large sample size (n = 3417) allowed analysis of 47 pesticides simultaneously, controlling for potential confounding by other pesticides in the model, and adjusting the estimates based on a prespecified variance to make them more stable. Results: Reported use of several individual pesticides was associated with increased NHL incidence, including organophosphate insecticides coumaphos, diazinon, and fonofos, insecticides chlordane, dieldrin, and copper acetoarsenite, and herbicides atrazine, glyphosate, and sodium chlorate. A subanalysis of these “potentially carcinogenic” pesticides suggested a positive trend of risk with exposure to increasing numbers. Conclusion: Consideration of multiple exposures is important in accurately estimating specific effects and in evaluating realistic exposure scenarios.
TL;DR: A conceptual model for epidemiological research on prolonged fatigue is presented and is the basis for the Maastricht Cohort Study and its relation with secondary health outcomes (psychological distress, need for recovery, and burnout).
Abstract: 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.
TL;DR: High levels of distress, and physical and psychosocial workplace factors are predictors of onset of pain in the neck and/or shoulders, particularly pain with pressure tenderness in the muscles.
Abstract: Aims: To quantify the relative contribution of work related physical factors, psychosocial workplace factors, and individual factors and aspects of somatisation to the onset of neck/shoulder pain.
Methods: Four year prospective cohort study of workers from industrial and service companies in Denmark. Participants were 3123 workers, previously enrolled in a cross sectional study, where objective measurement of physical workplace factors was used. Eligible participants were followed on three subsequent occasions with approximately one year intervals. Outcomes of interest were: new onset of neck/shoulder pain (symptom cases); and neck/shoulder pain with pressure tenderness in the muscles of the neck/shoulder region (clinical cases).
Results: During follow up, 636 (14.1%) participants reported neck/shoulder pain of new onset; among these, 82 (1.7%) also had clinical signs of substantial muscle tenderness. High shoulder repetition was related to being a future symptom case, and a future clinical case. Repetition was strongly intercorrelated with other physical measures. High job demands were associated with future status as a symptom case, and as a clinical case. A high level of distress predicted subsequent neck/shoulder pain, and neck/shoulder pain with pressure tenderness.
Conclusions: High levels of distress, and physical and psychosocial workplace factors are predictors of onset of pain in the neck and/or shoulders, particularly pain with pressure tenderness in the muscles.
TL;DR: A recent modification to the traditional definition of a confounder, which emphasises causal rather than statistical relationships, is described and illustrated and some well known problems in occupational epidemiology, arising from health related selection, are considered in the light of recent ideas.
Abstract: Confounding should always be addressed in studies concerned with causality. When present, it results in a biased estimate of the effect of exposure on disease. The bias can be negative—resulting in underestimation of the exposure effect—or positive, and can even reverse the apparent direction of effect. It is a concern no matter what the design of the study or what statistic is used to measure the effect of exposure.
The potential for confounding can be reduced by good study design, but in non-randomised studies this is unlikely to resolve the problem fully. Hence statistical adjustment methods, to reduce the bias caused by measured confounders, are also frequently considered. Such adjustment presupposes that one knows which factors are confounders. However, recent literature on methods for identifying confounders suggest that these are not always obvious. Indeed, in pursuit of guidelines, authors have had to reexamine the meanings of confounding and confounders with some ambiguity and conflict emerging. This literature is reviewed and a recent modification to the traditional definition of a confounder, which emphasises causal rather than statistical relationships, is described and illustrated. Some well known problems in occupational epidemiology, arising from health related selection, are considered in the light of recent ideas.
Control of confounding through study design is not addressed, nor is the article concerned with details of statistical methods for adjustment. An overview of design and analysis in relation to confounding by age may be useful additional reading.1 It is assumed that the reader has at least a basic knowledge of epidemiological methods. Unless otherwise stated, definitions and comments apply to all causal study designs including case–control studies.
### Example
Consider a study of the relationship between exposure to silica dust and lung cancer where the rate of lung cancer in exposed workers is twice that in unexposed subjects, giving …
TL;DR: This study corroborates the association between crystalline silica exposure and silicosis, lung cancer, COPD, and pulmonary tuberculosis and provides support for an association betweencrystalline silicas exposure and rheumatoid arthritis.
Abstract: Background: Although crystalline silica exposure is associated with silicosis, lung cancer, pulmonary tuberculosis, and chronic obstructive pulmonary disease (COPD), there is less support for an association with autoimmune disease, and renal disease.
Methods: Using data from the US National Occupational Mortality Surveillance (NOMS) system, a matched case-control design was employed to examine each of several diseases (including silicosis, lung cancer, stomach cancer, oesophageal cancer, COPD, pulmonary tuberculosis, sarcoidosis, systemic lupus erythematosus, systemic sclerosis, rheumatoid arthritis, and various types of renal disease). Cases were subjects whose death certificate mentioned the disease of interest. A separate control group for each of the diseases of interest was selected from among subjects whose death certificate did not mention the disease of interest or any of several diseases reported to be associated with crystalline silica exposure. Subjects were assigned into a qualitative crystalline silica exposure category based on the industry/occupation pairing found on their death certificate. We also investigated whether silicotics had a higher risk of disease compared to those without silicosis.
Results: Those postulated to have had detectable crystalline silica exposure had a significantly increased risk for silicosis, COPD, pulmonary tuberculosis, and rheumatoid arthritis. In addition, a significant trend of increasing risk with increasing silica exposure was observed for these same conditions and for lung cancer. Those postulated to have had the greatest crystalline silica exposure had a significantly increased risk for silicosis, lung cancer, COPD, and pulmonary tuberculosis only. Finally, those with silicosis had a significantly increased risk for COPD, pulmonary tuberculosis, and rheumatoid arthritis.
Conclusions: This study corroborates the association between crystalline silica exposure and silicosis, lung cancer, COPD, and pulmonary tuberculosis. In addition, support is provided for an association between crystalline silica exposure and rheumatoid arthritis.
TL;DR: The findings provided limited proof that SAM axis and HPA axis are disturbed among burnout patients, and elevated HR and elevated early morning cortisol levels may be indicative of sustained activation.
Abstract: Objectives: To investigate differences between burnout patients and healthy controls regarding basal physiological values and physiological stress responses. Measures of the sympathetic-adrenergicmedullary (SAM) axis and the hypothalamic-pituitary-adrenal (HPA) axis were examined. Methods: SAM axis and HPA axis activity was compared between 22 burnout patients and 23 healthy controls. SAM axis activity was measured by means of heart rate (HR) and blood pressure (BP). HPA axis activity was investigated by means of salivary cortisol levels. Resting levels of HR, BP, and cortisol were determined as well as reactivity and recovery of these measures during a laboratory session involving mental arithmetic and speech tasks. In addition, morning levels of cortisol were determined. Results: Burnout patients showed higher resting HR than healthy controls. BP resting values did not differ between burnout patients and healthy controls, nor did cardiovascular reactivity and recovery measurements during the laboratory session. Basal cortisol levels and cortisol reactivity and recovery measures were similar for burnout patients and healthy controls. However, burnout patients showed elevated cortisol levels during the first hour after awakening in comparison to healthy controls. Conclusions: The findings provided limited proof that SAM axis and HPA axis are disturbed among burnout patients. Elevated HR and elevated early morning cortisol levels may be indicative of sustained activation.
TL;DR: The number of cases of occupational asthma reported to the ONAP was approximately twice the number of compensated cases over the same period, and the relevance of the programme is confirmed by the reproducibility of the results, and its consistency with other surveillance programmes.
Abstract: Aims: To estimate the general and specific incidence of occupational asthma in France in 1996–99; and to describe the distribution of cases by age, sex, suspected causal agents, and occupation. Methods: New cases of occupational asthma were collected by a national surveillance programme, based on voluntary reporting, named Observatoire National des Asthmes Professionnels (ONAP), involving a network of occupational and chest physicians. For each case, the reporting form included information on age, sex, location of workplace, occupation, suspected causal agent, and methods of diagnosis. Estimates of the working population, used to calculate incidence rates by age, sex, region, and occupation, were obtained from the Institut National de la Statistique et des Etudes Economiques (INSEE) and from the French Securite Sociale statistics. Results: In 1996–99, 2178 cases of occupational asthma were reported to the ONAP, giving a mean annual rate of 24/million. Rates in men were higher than rates in women (27/million versus 19/million). The highest rate was observed in the 15–29 years age group (30/million). The most frequently incriminated agents were flour (20.3%), isocyanates (14.1%), latex (7.2%), aldehyde (5.9%), persulphate salts (5.8%), and wood dusts (3.7%). The highest risks of occupational asthma were found in bakers and pastry makers (683/million), car painters (326/million), hairdressers (308/million), and wood workers (218/million). Conclusion: Despite likely underreporting, the number of cases of occupational asthma reported to the ONAP was approximately twice the number of compensated cases over the same period. The relevance of the programme is confirmed by the reproducibility of the results year after year, and its consistency with other surveillance programmes. The ONAP programme is useful for the identification of targets for primary prevention.
TL;DR: In this article, a longitudinal study was performed with a follow up at 1 and 8 years among nurses employed at a large university hospital in Switzerland to describe the course of low back pain among nurses across eight years.
Abstract: Aims: To describe the course of low back pain (LBP) among nurses across eight years. Methods: A longitudinal study was performed with a follow up at 1 and 8 years among nurses employed by a large university hospital in Switzerland. A modified version of the Nordic Questionnaire was distributed to obtain information about demographic data, occupational activities, and various aspects of LBP. A clinical examination and several functional tests were used to overcome the problems associated with subjective pain reporting. Nurses having answered the questionnaire on all three occasions (n = 269) were classified into subgroups according to their pain intensity. For each subgroup the course of LBP was recorded. Results: LBP was highly prevalent with an annual prevalence varying from 73% to 76%. A large percentage (38%) indicated the same intensity of LBP on all three occasions. The proportion of nurses reporting repeated increase of LBP (19%) was approximately as large as the proportion who complained about repeated decrease of LBP (17%). Conclusion: It became evident that LBP poses a persistent problem among nurses. Over an eight year period almost half of the nurses indicated the same intensity of LBP, thus supporting a recurrent rather than a progressive nature of LBP.
TL;DR: The Fatigue Assessment Scale (FAS) had the highest factor loading on the one factor solution obtained in a factor analysis of the total scores of all scales.
Abstract: Aims: To compare the psychometric qualities of six fatigue questionnaires in a sample of working persons. Methods: Internal consistency and test-retest reliability, content validity, convergent validity, and the dimensionality of the fatigue instruments were explored. Results: All scales had a satisfactory internal consistency. Furthermore, based on factor analyses and Mokken scale analyses, all scales were unidimensional and appeared to measure an identical construct. The Fatigue Assessment Scale (FAS) had the highest factor loading on the one factor solution obtained in a factor analysis of the total scores of all scales. Conclusions: All the questionnaires were unidimensional and had good reliability and validity. The FAS was the most promising fatigue measure.
TL;DR: The psychometric properties of the DASS are suitable for use in an occupational health care setting and can be helpful in ruling out anxiety disorder and depression in employees with mental health problems.
Abstract: Methods: Internal consistency, construct validity, and criterion validity of the Depression Anxiety Stress Scales (DASS) were assessed. Furthermore, the ability to identify anxiety disorders or depression was evaluated by calculating posterior probabilities of these disorders following positive and negative test results for different cut off scores of the DASS-Depression and DASS-Anxiety subscales. Results: Internal consistency of the DASS subscales was high, with Cronbach's alphas of 0.94, 0.88, and 0.93 for depression, anxiety, and stress respectively. Factor analysis revealed a three factor solu- tion, which corresponded well with the three subscales of the DASS. Construct validity was further sup- ported by moderately high correlations of the DASS with indices of convergent validity (0.65 and 0.75), and lower correlations of the DASS with indices of divergent validity (range -0.22 to 0.07). Support for criterion validity was provided by a statistically significant difference in DASS scores between two diagnostic groups. A cut off score of 5 for anxiety and 12 for depression is recommended. The DASS showed probabilities of anxiety and depression after a negative test result of 0.05 and 0.06 respectively. Probabilities of 0.29 for anxiety disorder and 0.33 for depression after a positive test result reflect relatively low specificity of the DASS. Conclusion: The psychometric properties of the DASS are suitable for use in an occupational health care setting. The DASS can be helpful in ruling out anxiety disorder and depression in employees with mental health problems.
TL;DR: Fatigue was associated with short term but particularly with long term sickness absence, and the relation between fatigue and future sickness absence holds when controlling for work related and sociodemographic confounders.
Abstract: 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.
TL;DR: Receiving a permanent job contract after fixed term employment is associated with favourable changes in job security and job satisfaction, and the corresponding increase in sickness absence might be due to a reduction in presenteeism and the wearing off of health related selection.
Abstract: Aims: To determine whether change in employment status (from fixed term to permanent employment) is followed by changes in work, health, health related behaviours, and sickness absence.
Methods: Prospective cohort study with four year follow up. Data from 4851 (710 male, 4141 female) hospital employees having a fixed term or permanent job contract on entry to the study were collected at baseline and follow up.
Results: At baseline, compared to permanent employees, fixed term employees reported lower levels of workload, job security, and job satisfaction. They also reported greater work ability. All fixed term employees had a lower rate of medically certified sickness absence at baseline. Baseline rate ratios for those who remained fixed term were 0.64 (95% CI 0.55 to 0.75), and were 0.50 (95% CI 0.34 to 0.75) for those who later became permanent. Continuous fixed term employment was not associated with changes in the outcome measures. Change from fixed term to permanent employment was followed by an increase in job security, enduring job satisfaction, and increased medically certified sickness absence (compared to permanent workers rate ratio 0.96 (95% CI 0.80 to 1.16)). Other indicators of work, health, and health related behaviours remained unchanged.
Conclusion: Receiving a permanent job contract after fixed term employment is associated with favourable changes in job security and job satisfaction. The corresponding increase in sickness absence might be due to a reduction in presenteeism and the wearing off of health related selection.
TL;DR: Occupational exposure to OP pesticides was associated with deficits in a wider array of neurobehavioural functions than previously reported, perhaps because of higher exposure in this population.
Abstract: Aims: To identify neurobehavioural deficits among workers exposed to organophosphorous (OP) pesticides in their occupation. Methods: This study was conducted during the period when pesticides were applied to cotton crops in the fields in Menoufiya Governorate, Egypt. Fifty two occupationally exposed male workers were compared to 50 unexposed male controls who were similar in age, socioeconomic class, and years of education (⩾12 years). All participants completed a questionnaire (assessing personal, occupational, and medical histories), general and neurological clinical examination, neurobehavioural test battery (including tests for verbal abstraction, problem solving, attention, memory, and visuomotor speed), personality assessment, and serological analysis for serum acetylcholinesterase. Results: After correcting for confounders of age and education, the exposed participants exhibited significantly lower performance than controls on six neurobehavioural tests (Similarities, Digit Symbol, Trailmaking part A and B, Letter Cancellation, Digit Span, and Benton Visual Retention). A longer duration of work with pesticides was associated with lower performance on most neurobehavioural tests after adjusting for multiple comparisons. Although serum acetylcholinesterase was significantly lower in the exposed than the control participants, it was not significantly correlated with either neurobehavioural performance or neurological abnormalities. Conclusions: Occupational exposure to OP pesticides was associated with deficits in a wider array of neurobehavioural functions than previously reported, perhaps because of higher exposure in this population. Moderate chronic OP exposure may not only affect visuomotor speed as reported previously, but also verbal abstraction, attention, and memory.
TL;DR: A longitudinal study of neck and shoulder pain was carried out in female nurses at two hospitals in England as discussed by the authors, where a Cox regression model was used to estimate hazard ratios (HRs) for incident neck/shoulder pain during follow up in nurses who had been pain free for at least one month at baseline.
Abstract: Aim: To assess the incidence and risk factors for neck and shoulder pain in nurses. Methods: A longitudinal study of neck and shoulder pain was carried out in female nurses at two hospitals in England. Personal and occupational risk factors were assessed at baseline. The self reported incidence of symptoms in the neck and shoulder region was ascertained at three-monthly intervals over two years. A Cox regression model was used to estimate hazard ratios (HRs) for incident neck/shoulder pain during follow up in nurses who had been pain free for at least one month at baseline. Results: The baseline response rate was 56%. Of 903 women who were pain free at baseline, 587 (65%) completed at least one follow up while still in the same job. During an average of 13 months, 34% of these (202 women) reported at least one episode of neck/shoulder pain. The strongest predictor of pain in the neck/shoulder was previous history of the symptom (HRs up to 3.3). For physical exposures at work, the highest risks (HRs up to 1.7) were associated with specific patient handling tasks that involved reaching, pushing, and pulling. Nurses who reported low mood or stress at baseline were more likely to develop neck/shoulder pain later (HR 1.5). Workplace psychosocial factors (including job demands, satisfaction, and control) were not associated with incident neck/shoulder symptoms. Conclusions: Neck/shoulder pain is common among hospital nurses, and patient handling tasks that involve reaching and pulling are the most important target for risk reduction strategies.
TL;DR: It is indicated that being a new case of tennis elbow is associated with non-neutral postures of hands and arms, use of heavy hand held tools, and high physical strain measured as a combination of forceful work, non- neutral posture of Hands and Arms, and repetition.
Abstract: Aims: To assess the importance of physical and psychosocial risk factors for lateral epicondylitis (tennis elbow). Methods: Case-referent study of 267 new cases of tennis elbow and 388 referents from the background population enrolled from general practices in Ringkjoebing County, Denmark. Results: Manual job tasks were associated with tennis elbow (odds ratio (OR) 3.1, 95% confidence interval (CI) 1.9 to 5.1). The self reported physical risk factors “posture” and “forceful work” were related to tennis elbow. Among women, work involving performing repeated movements of the arms was related to tennis elbow (OR 3.7, CI 1.7 to 8.3). Among men, work with precision demanding movements was related to tennis elbow (OR 5.2, CI 1.5 to 17.9). Among both males and females, the results for work with hand held vibrating tools were inconsistent, partly because of few exposed subjects. A physical strain index was established based on posture, repetition, and force. The adjusted ORs for tennis elbow at low, medium, and high strain were 1.4 (CI 0.8 to 2.7), 2.0 (CI 1.1 to 3.7), and 4.4 (CI 2.3 to 8.7). Low social support at work, adjusted for physical strain, was a risk factor among women (OR 2.4, CI 1.3 to 4.6). Conclusion: Results indicate that being a new case of tennis elbow is associated with non-neutral postures of hands and arms, use of heavy hand held tools, and high physical strain measured as a combination of forceful work, non-neutral posture of hands and arms, and repetition. Furthermore, tennis elbow among women was associated with low social support at work. The results for precision demanding movements and for vibration were less consistent.