مدیریت استرس شغلی و مداخله ارگونومیک برای علائم مربوط به کار اندام فوقانی

In practice the secondary prevention of work-related upper extremity (WRUE) symptoms generally targets biomechanical risk factors. Psychosocial risk factors have also been shown to play an important role in the development of WRUE symptom severity and future disability. The addition of a stress management component to biomechanically focused interventions may result in greater improvements in WRUE symptoms and functional limitations than intervening in the biomechanical risk factors alone. Seventy office workers with WRUE symptoms were randomly assigned to an ergonomics intervention group (assessment and modification of work station and stretching exercises) or a combined ergonomic and job stress intervention group (ergonomic intervention plus two 1-h workshops on the identification and management of workplace stress). Baseline, 3- and 12-month follow-up measures of observed ergonomic risks and self-reported ergonomic risks, job stress, pain, symptoms, functional limitation, and general physical and mental health were obtained from all participants. While both groups experienced significant decreases in pain, symptoms, and functional limitation from baseline to three months with improvements continuing to 12 months post baseline, no significant differences between groups were observed for any outcome measures. Findings indicate that the additional two-session job stress management component did not significantly enhance the short- or long-term improvements brought about by the ergonomic intervention alone.

Work-related upper extremity (WRUE) symptoms can include pain, tenderness, swelling, numbness, and loss of function in the fingers, hands, forearms, shoulders, upper back, and neck (National Research Council and the Institute of Medicine, 2001). The exact etiology of these symptoms/disorders is currently unclear, however, research indicates that this problem is multi-factorial in development and therefore likely to be complicated in terms of prevention and treatment (National Research Council and the Institute of Medicine, 2001; Deveraux et al., 2002). Zwerling and colleagues (1997) reviewed the literature on the design, conduct and evaluation of occupational injury prevention interventions. They found that although the randomized controlled trial has been the standard of proof in medical and behavioral intervention studies for the last half-century, very few have actually been conducted in the field of occupational injury prevention. In their discussion of the most important methodological problems, they recognize that most companies will not “stand still” while waiting for an experimental intervention to work. They suggest that when companies take such a proactive approach to reducing occupational injuries, randomized trials may be the strongest way to truly evaluate the effectiveness of a specific intervention. The observable effect must be able to “rise above the noise” created by all the other efforts that may affect the injury problem (Zwerling et al., 1997). In their discussion of quasi-experimental studies, the same authors address the measurement difficulties, particularly in the prevention of musculoskeletal disorders that threaten the validity of intervention research. For example, the long latency period of many occupational musculoskeletal disorders may mean that the intervention may need to be in place for years to demonstrate an impact. Another challenge is worker compliance with recommendations (Zwerling et al., 1997). It is well known in the literature that changes in knowledge and skills do not necessarily change behavior. In addition, Zwerling and colleagues (1997) emphasize the importance of defining appropriate outcome variables in the area of musculoskeletal disorders that are reliable and valid. Investigations into the etiology of WRUE symptoms have identified three categories of risk factors for these problems: biomechanical exposures, psychosocial stressors, and individual risk factors (Bongers et al., 2002). Biomechanical exposures include factors such as poorly designed workplaces and biomechanical exposures such as repetitive motion, high forces, and deviations from neutral body alignments (National Research Council and the Institute of Medicine, 2001). Psychosocial stressors at work include factors such as high-perceived workplace stress, low-perceived social support, low-perceived job control, and time pressure (Bongers et al., 2002; Huang et al., 2003). Individual factors include gender (female), age, negative stress reactions—especially stomach reactions, and unsatisfactory leisure time and/or additional domestic workload (Bergqvist et al., 1995; Fredriksson et al. 1999). Much of the intervention research on WRUE symptoms and disorders has focused on modifying one or the other of these categories of risk factors, with most of the studies modifying either biomechanical exposures or psychosocial stress in the workplace (Lincoln et al., 2000; Piligan et al., 2000). Lincoln and colleagues (2000) examined interventions for the primary prevention of work-related upper extremity disorders. This systematic review included 24 total studies with asymptomatic workers that involved engineering controls (i.e., keyboard/mouse redesign), administrative controls (i.e., splint-wearing, training, exercise), or “multiple component” (i.e., redesign, training, and task rotation, etc.) interventions to determine which, if any, interventions were most effective. The most promising evidence was that the multi-component interventions in the review were correlated with a decrease in the incidence of WRUE disorders, including carpal tunnel syndrome, tendonitis, epicondylitis, and other conditions. The authors conclude that these multiple component interventions “may represent the best opportunity to reduce risk” (Lincoln et al., 2000) in primary prevention (asymptomatic workers) and perhaps may be equally or more relevant for secondary prevention (symptomatic workers) efforts in office workers. Piligan and colleagues (2000) conducted a review of the evaluation and management of a number of chronic WRUE disorders. In general, these authors recommend “conservative” treatment of these disorders, especially in the early symptomatic stages, using workplace evaluations for risk factors followed by modifications and rest to reduce inciting or aggravating positions and/or movements (Piligan et al., 2000). The literature and work in applied settings suggest that the most common approach to the secondary prevention of WRUE symptoms and disorders at the workplace involves ergonomic interventions that modify the person's workplace exposures to biomechanical risk factors for these symptoms/disorders. According to Piligan and colleagues (2000), the goals of this type of intervention are to (1) reduce awkward positions, (2) minimize the need to use excess force, (3) reduce highly repetitive movement, (4) reduce the period of time spent in one position, and (5) ensure sufficient rest/recovery periods. Studies have also examined the impact of job stress on WRUE symptoms and developed secondary prevention interventions to target these psychosocial risk factors. Pransky and colleagues (2002) conducted a systematic review of interventions for WRUE disorder that included job stress reduction. This review expanded on existing reviews that examined stress management interventions designed to reduce workplace stress in general to apply the findings to WRUE disorders interventions and symptomatic outcomes (Murphy, 1996). The findings of this review suggested that while interventions to date directed at workplace-level changes had minimal effect on stress levels and WRUE disorder outcomes, there was some evidence to indicate that individual-focused stress management interventions did improve self-reported stress and upper extremity symptoms, especially when combined with other elements, such as ergonomic training and interventions (Pransky et al., 2002). Faucett and colleagues (2002) conducted a randomized controlled trial of two types of worker training interventions (biofeedback and cognitive-behavioral, educational strategies) to prevent unnecessary muscle tension and WRUE symptoms. While the control group, who received the company's basic ergonomics training program, worsened over the 32-week trial, both experimental groups had modest improvement in symptom severity after completing the 6-h interactive training intervention. The significant difference among the groups from baseline to post-treatment at 6 weeks was largely due to the increase in control group symptoms and slight decrease in the educational group's symptom severity. Symptom severity for both groups worsened by the 32-week follow-up; the biofeedback group worsened to the level of the controls (Faucett et al., 2002). There are relatively few studies that have examined the effects of individual-focused job stress management and ergonomic interventions on WRUE symptoms and disorders (Pransky et al., 2002). The present study was intended to address this limitation in the literature by designing a randomized workplace study that targeted specific outcome measures including upper extremity pain, symptoms, functional limitations, job stress, and ergonomic risk exposures in office workers. An experimental job stress management training protocol was developed from current psychosocial theories that stipulate that workplace stressors contribute to WRUE symptoms by influencing biomechanical load, muscle tension and other stress responses, and symptom perception (Moon and Sauter, 1996; Bongers et al., 2002). In the present study, adult learning and cognitive-behavioral techniques were used to enhance workers’ understanding of WRUE symptoms and symptom management, relaxation, communication and problem-solving regarding stress at work. It was hypothesized that, compared to workers who received an ergonomic evaluation and tailored modifications of existing workstations (Piligan et al., 2002), symptomatic workers who received both the ergonomic and job stress management intervention would have greater improvement in outcomes.

The results of the present study indicate that WRUE symptomatic workers who received either the ergonomic intervention or the workstation modification intervention plus an additional two-meeting job stress management component experienced similar long-term improvements (at 3 and 12 months) in upper extremity pain and functional limitations. Improvements in reported generic physical health for both groups did not persist beyond three months. Because of the current emphasis in the literature on the importance of psychosocial factors in the development of WRUE symptom severity and disorders, it had been expected that by addressing both ergonomic and psychosocial job stress risk factors, clinical outcomes would be improved over traditional ergonomic intervention that focuses on adapting the work tasks and the work station to the individual. This hypothesis was not supported in the present study. Positive clinical outcomes were observed in both intervention groups regardless of the additional two-session psychosocial job stress management intervention component. The current results are contrary to Faucett et al. (2002) findings that after 32 weeks there was little improvement in either the ergonomic, cognitive-behavioral educational or biofeedback groups. The present investigation was designed as a randomized secondary prevention trial to examine the effectiveness of an individual-focused job stress management component on specific clinical outcome measures like self-reported pain, functional limitation, physical and mental health, job stress, and self-reported and observable ergonomic risk factors. The intervention was designed for and conducted in a very competitive workplace. Participation in this study was not on company time. The workers in the ergo-stress group agreed to attend the two job stress management meetings on their lunch breaks. It is not clear if extending the job stress management training to five or six weeks would have resulted in a differential group effect as has been shown in other studies with workers with chronic WRUE disorders (Spence, 1989 and Spence, 1991; Feuerstein et al., 1993). However, because of the particular workplace setting of the intervention, adding additional time to the intervention was not practical given the workplace's environment. Although a randomized, controlled trial methodology was used to allocate participants to treatments in the present study, we were unable to include a random sample of all symptomatic workers. Management precluded this possibility. This sampling limitation can result in a sampling bias. It is also possible that the job stress management component would have been effective in improving clinical outcomes given a larger sample. Placebo effects, cannot be ruled out. The attention given to the workers via the modifications of the existing workstations and the presence of the occupational health staff and support at the workplace (i.e., the ergonomics website) may have combined to create a positive outcome for the secondary prevention of WRUE symptoms independent of the job stress management component. Future studies should use larger sample sizes and incorporate wait-listed control groups in order to better determine the impact of psychosocial job stress intervention on WRUE symptom prevention. The purpose of the present study was to systematically evaluate the impact of one type of job stress management intervention component on specific WRUE outcomes in a randomized study conducted in the workplace while addressing as many methodological challenges as possible. The results showed that, in an applied setting, the addition of such a cognitive-behavioral educational component in the form of two 1-h meetings did not result in significant improvement in clinical outcomes compared to an ergonomic intervention alone. A limitation of the study is the absence of a placebo or no treatment control group. Therefore, non-specific effects such as the Hawthorne effect (Demure et al., 2000) or regression to the mean cannot be ruled out as possible explanation for the changes in both groups. The absence of any differences between those who completed the study and those who did not complete the study in terms of socio-demographic and outcome measures suggests that the group that remained in the study was similar to the initial group that met criteria for this study. However, high work commitment, meetings with short notice, and frequent travel seemed to affect adherence and dropout rates in this study. Indeed, commitment to the institution's mission was very high among staff, presenting a challenge for maintaining a healthy balance of work and personal life (Dimberg et al., 2001). This may lead to strong prioritization of work assignments, long working hours and tight deadlines. Such institutional stressors will not be alleviated solely by applying only the strategies taught in the two-meeting job stress management intervention of the present study. Our group has recently investigated specific work organization and job stressors (i.e., time pressure, interpersonal demands) in office workers and found that these factors are associated with UE symptoms (Huang et al., 2003). The present study did not directly modify these stressors. Such an effort might result in improved outcomes. It is also possible that a more focused intervention directed at those factors that are empirically linked to upper extremity symptoms measured at baseline within a specific workforce and workplace could result in improved symptom management. These two intervention options require systematic evaluation. The results of this study may be further enhanced in the future by a focus on specific job stressors and cognitive and behavioral factors that recently have been shown to be specifically related to musculoskeletal health (Feuerstein, 1996; Feuerstein et al., 1999). Recent research suggests that workstyle, or how a person responds to work demands, may be related to upper extremity symptoms (Haufler et al., 2000). A scale has been recently developed that measures different features of workstyle (Feuerstein et al., in press). Coupled with ergonomic changes, interventions that address these specific job factors and work style that maybe triggered by these factors may have greater short- and long-term effects.