Motivation
Stress
Psychosocial disorders Psychosocial Factors While the etiologic mechanisms are poorly understood, there is increasing evidence that psychosocial factors related to the job and work environment play a role in the development of work-related musculoskeletal disorders (MSDs) of the upper extremity and back. Though the findings of the studies reviewed are not entirely consistent, they suggest that perceptions of intensified workload, monotonous work, limited job control, low job clarity, and low social support are associated with various work-related musculoskeletal disorders. As some of these factors are seemingly unrelated to physical demands, and a number of studies have found associations even after adjusting for physical demands, the effects of these factors on MSDs may be, in part or entirely, independent of physical factors. It is also evident that these associations are not limited to particular types of jobs (e.g., video display terminal work [VDT]) or work environments (e.g., offices) but, rather, seem to be found in a variety of work situations. This seems to suggest that psychosocial factors may represent generalized risk factors for work-related MSDs. These factors, while statistically significant in some studies, generally have only modest strength. At present, two of the difficulties in determining the relative importance of the physical and psychosocial factors are: (1) psychosocial factors are usually measured at the individual level, while physical factors are more often measured at the group (e.g., job or task) level and often by methods with limited precision or accuracy and (2) “objective measures" of aspects of the psychosocial work environment are difficult to develop and are rarely used, while objective methods to measure the physical environment are more readily available. Until we can measure most workplace and individual variables with more comparable techniques, it will be hard to determine precisely their relative importance. There is considerable confusion regarding the contribution of psychosocial factors to musculoskeletal illness and injury. Unlike the more finite (and generally more familiar) range of physical factors (e.g., force, repetition, and posture), the concept of psychosocial factors includes a vast array of conditions. Indeed, the term “psychosocial” is commonly used in the occupational health arena as a catchall term to describe a very large number of factors that fall within three separate domains: (1) factors associated with the job and work environment, (2) factors associated with the extra-work environment, and (3) characteristics of the individual worker. Interactions among factors within each of these domains constitute what is referred to as a “stress process,” the results of which are thought to impact upon both health status and job performance [Bongers and deWinter 1992; ILO 1986; Sauter and Swanson 1996; WHO 1989]. PSYCHOSOCIAL PATHWAYS The purpose of this discussion is to summarize research evidence linking work-related psychosocial factors, as described above, to MSDs of the neck, shoulder, elbow, hand/wrist, and back. It should be recognized at the outset, however, that the linkages between work-related psychosocial factors and health outcomes of all varieties are often complex and influenced by a multitude of conditions. In particular, both personal and situational characteristics may lead to differences in the way individuals exposed to the same job and work environment perceive and/or react to the situation [Hurrell and Murphy 1992]. Recent theoretical models of the relationship between psychosocial factors and MSDs [Bongers et al. 1993; Sauter and Swanson 1996] clearly reflect the complexity and multifactorial nature of the problem. In general, four plausible types of explanations have been suggested to account for associations between work-related psychosocial factors and MSDs [Bergqvist 1984; Bongers et al. 1993; Bernard et al. 1993; Sauter and Swanson 1996; Sauter et al. 1983; Ursin et al. 1988]. First, psychosocial demands may produce increased muscle tension and exacerbate task-related biomechanical strain. Second, psychosocial demands may affect awareness and reporting of musculoskeletal symptoms, and/or perceptions of their cause. Within this second explanation may fall the “perverse incentive” view, in which societies may provide workers with systems (such as workers' compensation) that may lead to overreporting of MSD symptoms [Frank et al. 1995]. Third, initial episodes of pain based on a physical insult may trigger a chronic nervous system dysfunction, physiological as well as psychological, which perpetuates a chronic pain process. Finally, in some work situations, changes in psychosocial demands may be associated with changes in physical demands and biomechanical stresses, and thus associations between psychosocial demands and MSDs occur through either a causal or effect-modifying relationship. The research evidence reviewed in the following discussion is organized into two separate sections. The first section includes studies of disorders of the neck, shoulder, elbow, hand and wrist which are discussed under the rubric of “upper extremity disorders.” This convention was adopted because many of the studies utilize measures which combine symptoms associated with several upper extremity body areas (e.g., neck and shoulder), and it is therefore not possible inreviewing these studies to isolate the effects of the psychosocial variables under consideration on more specific areas. The second section examines studies of back disorders. Associations reported in this review are statistically significant in nearly all cases (at the p<0.05 level and frequently also at the p<0.01 level). Where possible, odds ratios (ORs) are also reported. The studies examined in this review are summarized in Tables 7-1 and 7-2. In interpreting the studies reviewed, it is necessary to be aware that, in general, researchers have not used standardized methods for assessing psychosocial factors in relationship to MSDs. Thus, individual psychosocial factors assessed by investigators vary from study to study. Moreover, even when work-related psychosocial factors (e.g., workload , job control, social support, job satisfaction, etc.) included by various investigators are the same or similar, they may be measured by different methods and different kinds of scales which can vary in psychometric quality. These methodological limitations complicate the process of drawing definitive conclusions regarding the literature as a whole and when comparing results between studies, one must take these differences into account. |