Effort-reward imbalance and video display unit postural risk factors interact in women on the incidence of musculoskeletal symptoms.

OBJECTIVE: This study investigated gender-specific interaction between effort-reward imbalance and video display unit (VDU) postural risk factors at work on the incidence of self-reported musculoskeletal symptoms in the shoulder-neck, lower back and upper limbs regions. PARTICIPANTS: A cohort of 2,431 VDU users - consisting of white-collar workers in three Canadian public service organizations - was assessed on postural risk factors and effort-reward imbalance at work. METHODS: After a mean follow-up time of three years, the six-month incidence proportion of musculoskeletal symptoms in each body region was measured. Interaction was estimated with the attributable proportion of cases due to interaction. RESULTS: For women, two significant attributable proportions due to interaction between effort-reward imbalance and postural risk factors were observed in the shoulder-neck (64%) and upper limbs (57%) regions, while an interaction of 25%, although not significant, was observed in the lower back. No interaction was observed for men. CONCLUSIONS: This interaction means that, among women, when effort-reward imbalance and postural risk factors are simultaneously present, the incidence of musculoskeletal symptoms is greater than the sum of effects of the individual factors. Successful interventions on either one of these exposures would thus have the supplemental benefit of preventing cases due to interaction.

Implementation of an organizational-level intervention on the psychosocial environment of work: comparison of managers' and employees' views.

OBJECTIVE: To compare employees' and managers' perceptions of implemented changes in an organizational-level workplace intervention. METHODS: Nine departments participated in an intervention aimed at reducing adverse psychosocial work environment factors. On the basis of a prior risk evaluation, department managers were responsible for decisions and implementation of the intervention, that is, work changes. These were recorded in logbooks, which were compared to employees' questionnaire ratings of the changes. RESULTS: For half of the changes, proportion of employees reporting that a specific change was implemented did not correspond with the amount of manager-reported changes. CONCLUSIONS: Evaluation of employees' and managers' perceptions of an organizational-level intervention is crucial, since these perceptions do not necessarily fully correspond. Employees perceived changes that were not reported by department managers and they also did not perceive exposure to all changes reported by the managers.

Interaction between postural risk factors and job strain on self-reported musculoskeletal symptoms among users of video display units: a three-year prospective study.

OBJECTIVE: This study investigated a possible interaction between postural risk factors and job strain on the incidence proportion of self-reported musculoskeletal symptoms in the shoulder-neck, lower back and upper limbs regions. METHODS: A cohort of white-collar workers (N=2431) was assessed with a self-administered questionnaire regarding postural risk factors and job strain at work. After a three-year follow-up, the six-month incidence proportion of musculoskeletal symptoms in the three body regions was measured with a modified version of the Nordic questionnaire. The analyses were stratified for gender. Interaction was defined as a departure from the addition of effects of individual risk factors, and its importance was estimated from the attributable proportion due to interaction and its 95% confidence interval (95% CI). RESULTS: A significant attributable proportion of 0.80 (95% CI 0.23-1.37) due to interaction between postural risk factors and job strain was observed for men in the lower back region. An indication of interaction was found for women with attributable proportions due to interaction of 0.44 (95% CI -0.06-0.94), 0.27 (95% CI -0.34-0.88) and 0.36 (95% CI -0.33-1.05) for the shoulder-neck, lower back, and upper limbs regions, respectively. CONCLUSIONS: The simultaneous presence of postural risk factors and job strain seems to increase the pathogenic effect of each exposure on the incidence proportion of musculoskeletal symptoms. This interaction effect is important for work intervention practices as success in decreasing any of these two risk factors could have the additional benefit of reducing up to 80% of new cases of musculoskeletal symptoms among participants exposed to both risk factors.

Agreement between a self-administered questionnaire on musculoskeletal disorders of the neck-shoulder region and a physical examination.

BACKGROUND: In epidemiological studies on neck-shoulder disorders, physical examination by health professionals, although more expensive, is usually considered a better method of data collection than self-administered questionnaires on symptoms. However, little is known on the comparison of these two methods of data collection. The agreement between self-administered questionnaires and the physical examination on the presence of neck-shoulders disorders was assessed in the present study. METHODS: This study was conducted among clerical workers using video display units. Prevalent cases were workers for whom neck-shoulder symptoms were present for at least 3 days during the previous 7 days and for whom pain intensity was greater than 50 mm on a 100 mm visual analogue scale. All 85 workers meeting this definition and a random sample of 102 workers who did not meet this definition were selected. Physical examination included measures of active range of motion and musculoskeletal strength. Cohen's kappa and global percent agreement were calculated to compare the two methods of data collection. The effect on the agreement of different question and physical examination definitions and the importance of the time interval elapsed between the administrations of the tests were also evaluated. RESULTS: Kappa coefficients ranged from 0.19 to 0.54 depending on the definitions used to ascertain disorders. The agreement was highest when the two instruments were administered 21 days apart or less (Kappa = 0.54, global agreement = 77%). It was not substantially improved by the addition of criteria related to functional limitations or when comparisons were made with alternative physical examination definitions. Pain intensity recorded during physical examination maneuvers was an important element of the agreement between questionnaire and physical examination findings. CONCLUSION: These results suggest a fair to good agreement between the presence of musculoskeletal disorders ascertained by self-administered questionnaire and physical examination that may reflect differences in the constructs measured. Shorter time lags result in better agreement. Investigators should consider these results before choosing a method to measure the presence of musculoskeletal disorders in the neck-shoulder region.

Fatigue management by truck drivers in real life situations: some suggestions to improve training.

Truck driver fatigue is a major safety issue for truck drivers and the public in general. Although training prepares drivers to effectively operate a truck, it tends to minimize the importance of working constraints faced daily on-the-job and thus reduces its impact on safety and effectiveness. With experience, drivers develop skills to combat fatigue. Documenting these skills can contribute to improved training of apprentices. An ethnographic approach was used to better understand the real-life fatigue management skills of truck drivers. Participant observation was used to analyze the activity of apprentices in training and the activity of truck drivers at work. Observations indicated that training focused on time management and regulations, but did not prepare trainees to manage real-life constraints. Experienced drivers were not merely managing time; rather they were managing working constraints (including time) as a whole. To do so, they used two strategies: managing psycho-physical transformations and dynamic work planning. By integrating psycho-physical preoccupations into all aspects of work and by preparing future drivers to face real-life constraints, we could better train and prepare apprentices. Drivers do develop effective skills to combat fatigue which can improve training and better prepare future drivers to face daily constraints. These improvements can have a significant impact on fatigue and safety in the transportation industry.

Allowing for MSD prevention during facilities planning for a public service: an a posteriori analysis of 10 library design projects.

Research was conducted to identify an ergonomics-based intervention model designed to factor in musculoskeletal disorder (MSD) prevention when library projects are being designed. The first stage of the research involved an a posteriori analysis of 10 recent redesign projects. The purpose of the analysis was to document perceptions about the attention given to MSD prevention measures over the course of a project on the part of 2 categories of employees: librarians responsible for such projects and personnel working in the libraries before and after changes. Subjects were interviewed in focus groups. Outcomes of the analysis can guide our ergonomic assessment of current situations and contribute to a better understanding of the way inclusion or improvement of prevention measures can support the workplace design process.

Conditions that influence the elimination of postural constraints after office employees working with VDU have received ergonomics training.

OBJECTIVE: The goal of this article is to better understand how preventive measures are undertaken after training. It examines how certain variables, such as musculoskeletal pain, participant age and workstation and work content characteristics influence the reduction of postural constraints after office employees working with a computer have received ergonomics training. METHODS: A pre-test/post-test design was used. The 207 female office workers were given 6 hours of ergonomics training. The variables were determined using a self-administered questionnaire and an observation grid filled out 2 weeks before and 6 months after the training session. The FAC and HAC were used in the data processing. RESULTS: The presence or absence of musculoskeletal pain had no statistically significant influence on whether or not postural constraints were eliminated. The age of the participants and the possibility of adjusting the workstation characteristics and work content produced differentiated results with regard to postural constraint reduction. We concluded that trained people succeed in taking relevant and effective measures to reduce the postural constraints found in VDUs. However other measures than work station adjustments lead to this prevention and such training must be strongly supported by the various hierarchical levels of an enterprise or an institution.

Job strain and neck-shoulder symptoms: a prevalence study of women and men white-collar workers.

BACKGROUND: Neck-shoulder symptoms are frequent among workers. Psychosocial factors at work have been associated with neck-shoulder symptoms, but few studies have examined job strain, the combined effect of high psychological demands (PD) and low decision latitude (DL). AIMS: To examine the association between psychosocial factors at work and the prevalence of self-reported neck-shoulder symptoms among white-collar workers. METHODS: In a cross-sectional study of 1543 white-collar workers, PD and DL at work were measured with Karasek's questionnaire. Prevalent cases were workers for whom neck-shoulder symptoms were present for >or=3 days during the previous 7 days and for whom pain intensity was greater than half the visual analogue scale. Gender and social support at work were evaluated as potential effect modifiers. RESULTS: Workers exposed to high job strain had a higher prevalence of neck-shoulder symptoms [adjusted prevalence ratio (PR): 1.54, 95% confidence interval (CI): 1.00-2.37]. No modifying effect of gender was observed in this association. The effect of job strain was stronger in workers with low social support (adjusted PR: 1.84, 95% CI: 0.92-3.68). These associations tended to be stronger and/or more precise when using alternative exposures and case definition. Namely, a stronger job strain effect was observed when a tertile cut-off was used to classify exposure (adjusted PR: 2.47, 95% CI: 1.15-5.32). CONCLUSION: These results suggest that primary prevention of neck-shoulder symptoms among white-collar workers should consider the exposure to job strain, especially when workers are exposed to low social support at work.

Understanding the transfer of knowledge and skills from training to preventive action using ergonomic work analysis with 11 female VDT users.

A qualitative evaluation of 11 VDT users, who participated in a training program for the prevention of musculoskeletal and visual problems, investigated the extent of the application of the taught principles in everyday work. Data were collected over a 2 to 3 day period for each trainee, through an ergonomic work analysis in situ and semi-structured interviews, followed by recommendations, when appropriate, corresponding to the taught principles. A case analysis and a cross analysis of the data provided information about the developed ability for self-analysis of work regarding posture and visual comfort and what influenced it. A model depicting the process of transfer of knowledge and skills, from the training program to preventive action, was abstracted from data analysis. This model allows both the identification of problems in applying taught principles and the means to readjust the training program.