The relations between work demands and health complaints in lorry drivers

In this study, data of a questionnaire study among 439 lorry drivers were fitted to a model in which work demands and the worker's decision latitude are related to musculoskeletal complaints and general psychosomatic complaints. Structural analysis with LISREL was used to investigate the hypothesized relations. Two modifications resulted in a ² of overall fit equal to 77.35 with 47 degrees of freedom. The quality of model fit was considered to be satisfactory when the sample size was taken into account. The values of the Adjusted Goodness of Fit Index (0.948) and the Root Mean Square Residuals (0.029) indicated the same. The standardized solution of LISREL showed that work demands with respect to task contents were significantly related to musculoskeletal complaints as well as to general psychosomatic complaints (0.75 and 0.34 respectively, both P < 0.001). This conceptual variable was indicated by physical activities that the drivers had to perform. The relations between work-related psychosocial factors and musculoskeletal complaints were weak. Another significant effect on general psychosomatic complaints was found for work demands with respect to terms of employment (0.30, P < 0.001). This conceptual variable was indicated by variables concerning working hours and pressure of the work. It is recommended that in future occupational epidemiology, both physical and psychosocial aspects of the working situation be related to health effects, rather than solely a single exposure variable.     

Gender differences in upper extremity musculoskeletal complaints in the working population

Objectives: This study analysed the association between gender and upper extremity musculoskeletal complaints, among the general working population and in various occupational groups. The hypothesis was tested whether the higher risk for women in the general working population for these complaints could partly be explained by differences in the distribution of men and women in occupations with different risks for the onset of upper extremity musculoskeletal complaints. Methods: The data for this study came from cross-sectional questionnaire data from 16,874 employees categorised in 21 different occupational classes. Associations between gender and complaints of the upper extremities were analysed for the total study sample and for each occupational class separately. An adjustment was made for the variable `occupational class' in the final model in order to study the impact of occupational gender segregation on gender differences in upper extremity complaints in the working population. Results: In the total study sample, significantly higher risks of complaints of the neck, shoulder, elbow, and wrist among the women were observed. Within many occupational classes, women reported significantly higher risks than did men, in particular for complaints of the neck and shoulder. Adjustment for occupational class showed increased risks for female workers for complaints of the neck, shoulder, elbow, and wrist, hence, rejecting our hypothesis on occupational gender segregation as an explanation for the higher risks for upper extremity complaints among women in the general working population. Conclusions: This study confirmed the presence of gender differences in upper extremity musculoskeletal complaints among the working population and in many occupational classes, with female workers having the higher risk. The results, however, do not lend support to a differential occupational exposure theory as an explanation for the higher risks for these complaints among women in the general working population. Careful consideration of gender influence in ergonomic epidemiological studies is recommended. Received: 16 February 2000 / Accepted: 10 June 2000     

Review of the factors associated with musculoskeletal problems in epidemiological studies

Objectives: To review systematically all epidemiological studies of the past 15 years concerning the factors associated with musculoskeletal disorders (MSDs) or complaints of the neck and upper limbs. Methods: Fifty-seven cross-sectional and seven longitudinal studies were reviewed. A list was made of all personal, occupational, extra-occupational and psycho-organisational factors taken into consideration in each study, and of those that were found in association with MSDs. MSDs of the neck-shoulder region (NSs) and hand-wrist (HWs) were considered separately. About 70 different factors are listed. Results: This inventory identifies the factors or categories of factors that were generally taken into consideration. It makes it possible also to evaluate the strength of the association with a given factor, in considering the number of studies finding an association, and those that did not consider this factor. Based on this review, some factors taken into consideration (such as weight or hobbies) could be excluded in further studies, and replaced by more specific psycho-organisational factors. Received: 3 July 2000 / Accepted: 31 October 2000     

Prevalence of irritative symptoms in a nonproblem air-conditioned office building

Objectives: To assess the prevalence of work-related complaints and symptoms in employees in an air-conditioned office building (Building AC) in a mild climatic area (Italy). No discomfort had previously been reported. Methods: A total of 198 employees in Building AC and 281 controls working in three naturally ventilated buildings (Building NV) answered a questionnaire investigating work-related complaints and symptoms. Results: A significantly higher percentage of workers in Building AC reported a lack of comfort in the working environment as compared with the controls (30.6% versus 18.9%). The most common complaints were strong lighting, high temperature, and dry, dusty, and/or stuffy air. The prevalence of ocular, upper airway, and cutaneous symptoms was significantly higher (29.8% versus 14.9%, 25.3% versus 9.6%, and 14.1% versus 3.6%, respectively). No significant difference was observed in respiratory or general symptoms. Logistic regression analysis showed that working with video display units and photocopiers influenced ocular symptoms; upper airway and cutaneous symptoms were influenced by female gender and working in the air-conditioned building. Conclusions: In an apparently healthy air-conditioned office building, complaints and symptoms are reported more often than in a naturally ventilated edifice, but the prevalence is lower than that usually observed in sick buildings. Symptoms are influenced by individual and work-related characteristics. Received: 17 September 1997 / Accepted: 26 February 1998     

The trucker strain monitor: an occupation-specific questionnaire measuring psychological job strain

Objectives: To develop and validate a short and user-friendly questionnaire measuring psychological job strain in truck drivers. Methods: In cooperation with an occupational physician in the Dutch road transport industry we developed items on the basis of face validity and information of existing questionnaires on the subject. These items were pilot-tested, by means of interviews, in 15 truck drivers. Study I examined the factorial structure of the initial 30-item trucker strain monitor (TSM) in a sample of 153 truck drivers. Subsequently, number of items per factor was reduced on the basis of reliability analyses (Cronbach's alpha). Study II examined construct and criterion validity of the TSM in a randomly selected group of 2,000 truck drivers, of whom 1,111 participated (adjusted response=63%). Additionally, sensitivity and specificity were assessed by examining the ability of the TSM to identify truck drivers with or without self-reported sickness absence in the past 12 months because of psychological complaints. Results: Factor analyses of the initial 30-item TSM revealed a two-factor solution. Item reduction resulted in a six-item work-related fatigue scale and four-item sleeping problems scale with high internal consistency. Results of study II confirmed the internal consistency of the TSM scales and provided support for construct and criterion validity. The composite, work-related fatigue, and sleeping problems scale had a sensitivity of 83%, 80% and 71% respectively, in identifying truck drivers with prior sickness absence because of psychological complaints. Specificity rates were 72%, 73% and 72% respectively. Conclusion: Despite methodological limitations, the results suggest that the TSM is a reliable and valid indicator of psychological job strain in truck drivers. In particular, the composite and work-related fatigue scale identified drivers with prior absenteeism because of psychological complaints, quite accurately. Future longitudinal research in specific sub-groups of truck drivers including both self-reported and objective psychological health measures should evidence whether (1) the distinction between two indicators of psychological job strain is useful, and whether (2) the TSM can be used in screening out truck drivers at risk of developing psychological health problems. Received: 20 July 2000 / Accepted: 30 March 2001     

Productivity Loss at Work; Health-Related and Work-Related Factors

Introduction Productivity loss is an increasing problem in an aging working population that is decreasing in numbers. The aim of this study is to identify work-related and health-related characteristics associated with productivity loss, due to either sickness absence or reduced performance at work. Methods In this cross-sectional study, data of the Netherlands Working Conditions Survey of 2007 were used, which includes a national representative sample of 22,759 employees aged 15 to 64 years. Demographic characteristics, health-related and work-related factors were assessed with a questionnaire. Logistic regression analyses were carried out to study the relationship of work-related and health-related factors with low performance at work and sickness absence in the past 12 months. Results Poor general health, the number of longstanding health conditions, and most types of longstanding health conditions were associated with productivity loss. Health-related factors were in general stronger associated with sickness absence than with low performance at work. Performance: poor health OR 1.54 CI 1.38–1.71, >1 health conditions OR 1.21 CI 1.09–1.35; sickness absence: poor health OR 2.62 CI 2.33–2.93, >1 health conditions OR 2.47 CI 2.21–2.75. Of the different types of longstanding health conditions, only psychological complaints and to a small extent musculoskeletal symptoms, were associated with low performance (respectively OR 1.54 CI 1.27–1.87; OR 1.09 CI 1.00–1.18). Low performance at work was less likely among employees with high physically demanding work (shift work OR 0.70 CI 0.63–0.76, using force OR 0.78 CI 0.72–0.84, and repetitive movements OR 0.74 CI 0.70–0.79). Psychosocial factors were stronger associated with low performance at work than with sickness absence (performance: job autonomy OR 1.28 CI 1.21–1.37, job demands OR 1.23 CI 1.16–1.31, emotionally demanding work OR 1.73 CI 1.62–1.85; sickness absence: job autonomy ns, job demands OR 1.09 CI 1.03–1.17, emotionally demanding work OR 1.09 CI 1.02–1.16). Conclusion Except for psychological complaints, workers with a longstanding health condition generally perform well while being at work. Nevertheless, the likelihood of taking sick leave is increased. Among work-related factors, psychosocial work characteristics have the strongest relation with productivity loss, mostly with performance while at work.     

Exposure-response relationships in rhinitis and conjunctivitis caused by methyltetrahydrophthalic anhydride

Objective: To examine exposure-response relationships in the occurrence of symptoms of the eyes and airways in workers exposed to methyltetrahydrophthalic anhydride (MTHPA). Methods: A population of 111 workers from 2 condenser plants (A and B) using epoxy resin with MTHPA underwent a questionnaire survey and serology investigations, and data obtained on 95 subjects in assembly and inspection lines were analyzed for this study. Results: In all, 24 (65%) of 37 workers in plant A and 38 (66%) of 58 workers in plant B had positive MTHPA-specific IgE. The air levels of MTHPA detected in assembly and inspection lines were higher in plant A than in plant B (geometric mean 25.5–63.9  and 4.93–5.49 μg/m³, respectively). IgE-sensitized workers in each plant had significantly (P < 0.05) more complaints regarding the eyes and nose than did unsensitized workers, suggesting that there is an IgE-mediated mechanism in most of these symptoms. The sensitized workers in plant A had higher frequencies for symptoms of the eyes, nose, and pharynx than did those in plant B (P < 0.02). Furthermore, only 15% of persons often displayed work-related symptoms among the 20 symptomatic workers in plant B as compared with 73% of the 26 symptomatic workers in plant A (P < 0.0001). These results can be explained by the difference in the MTHPA levels measured in the lines between the two plants. In plant B the minimal level of MTHPA that was associated with work-related symptoms was 15–22 μg/m³, which was lower than the geometric mean levels detected in assembly and inspection lines in plant A. Conclusions: These results suggest that MTHPA exposure at levels above 15 μg/m³ should be avoided to prevent the development of occupational allergic diseases in most workers. Received: 4 May 1998 / Accepted: 4 August 1998     

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. Received: 22 July 1999 / Accepted: 4 December 1999     

Neurological and functional effects of short-term exposure to hand-arm vibration

Objective: The aim of the present study was to quantify the sensory and functional effects resulting from a short-duration (30 min) exposure to hand-arm vibration. Subjects and methods: Nine subjects went through nine laboratory experiments. For 32 min they grasped a handle vibrating at three different amplitudes (5, 20, and 80 ms⁻²) and at three frequencies (31.5, 125, and 500 Hz). Additionally, a reference experiment was conducted in which the handle did not vibrate. Three sensory tests [vibration perception threshold (VPT), pressure perception threshold (PPT), and distal sensory latency time (DSL)], two functional tests [Purdue pegboard (PPB) and maximal voluntary force (MVF)], and a questionnaire concerning the perceived paresthesia and numbness were completed before, during, and after exposure. Results: A 32-min period of exposure to vibration leads to a temporary threshold shift (TTS) of the VPT and to the development of paresthesia and numbness. The VPT appears to vary with the exposure duration according to a first-order model with a time constant about equal to 3 min. The TTS increases with the vibration acceleration amplitude and is greater for an exposure frequency of 125 Hz than for that of 31.5 or 500 Hz. It is also greater at the test frequency 125 Hz than at 31.5 Hz. The other tests do not demonstrate any significant variation. In particular, the PPB test does not demonstrate any loss of dexterity. Conclusion: After some 30 min of exposure to vibration the VPTs are increased and paresthesia and numbness develop. However, these do not appear to influence significantly the capacity or performance at work. Received : 7 April 1997 / Accepted: 25 September 1997     

Fatigue,emotional exhaustion and perceived health complaints associated with work-related characteristics in employees with and without chronic diseases

Objectives Ageing of the Dutch working force and increasingly more stringent restrictions regarding early retirement and disability benefits are leading to higher numbers of workers with ill health. Until now, only a few studies have explored how employees with ill health perceive their work. This study investigated possible differences in scores on fatigue, emotional exhaustion, perceived health complaints and various work-related characteristics between chronically ill (CIWs) and non-chronically ill workers (NCIWs), as well as differences in associations between work- and health-related characteristics. Methods A questionnaire was sent to all employees of a Dutch university to collect data on perceived work-related and health-related characteristics (response 49.1%). Differences in various scores were analysed using χ ²-tests and the general linear model. Associations between the work- and the health-related characteristics were determined by multiple linear regression analyses in the CIWs (n = 444) and NCIWs (n = 1,347) separately. Interaction terms were included to detect differences between the two groups. Results The results indicated that the CIWs had less favourable scores on the three health-related characteristics. Also, the CIWs scored less favourably than the NCIWs on almost all the work-related characteristics. In the two groups, negative work-related aspects, such as higher work pressure, contributed most to explaining the variance in the health-related characteristics. However, in the CIWs, fatigue was not explained by the work-related aspects as much as in the NCIWs. In the CIWs, the association between unpleasant treatment and the health-related characteristics was stronger than in the NCIWs, but there were indications that autonomy, possibilities for learning and social support from superiors also played an important role. Conclusions CIWs perceived more fatigue, emotional exhaustion and health complaints than NCIWs. There were different patterns of associations between work- and health-related characteristics in the NCIWs and CIWs. Future studies on associations between work-related characteristics and health should take the presence of chronic disease into account.