Evaluating stability and reactivity in work-related overcommitment under the ERI model : does the shortened questionnaire lead to changes in model properties?

Fahlen, G. (2008). Aspects on the Effort-reward Imbalance model of psychosocial stress in the work environments. Sundsvall, Sweden: Mid Sweden University, Department of Health Sciences. ISBN 978-91-85317-94-3. Since the late 1970s, work related stress has increasingly been recognized as an important determinant for ill-health and disease. One of the most influential stress models is the Effort-Reward Imbalance model (ERI), which stipulates that an imbalance between the perceived effort spent at work and rewards received results in noxious stress. Those with a coping behaviour called Work-related Overcommitment (WOC), including an inability to withdraw from work obligations are especially vulnerable. The model has shown strong explanatory value for a large numbers of harmful health outcomes. The general aim of this thesis was to contribute to the development of the ERI model by exploring the properties of this model in relation to its theoretical assumptions, construct, and application and to improve the knowledge of validity of the ERI-model. The study sample that was used in three papers emanated from the WOLF study (Work, Lipids and Fibrinogen). The analyses were confined to the subset of individuals who answered the ERI questions (n=1174) with complete answers. In one paper, data from the SKA study (Sick leave, Culture and Attitudes) were used and they comprised all employees at the Swedish Social Insurance Agency responsible for management and compensation of illness in the working population (n=5700). All data are based on questionnaires. The results indicate that ERI and WOC are risk factors for sleep disturbances and fatigue. A palpable threshold effect was seen between quartile three and four. Since these symptoms are strongly stress related, our results support the utility of the ERI and WOC scales in assessing stress in working life. Agreement between single questions in the original and an approximate instrument for measuring ERI were low, whereas the agreement between the two ERI scales was reasonable. When approximate instruments are used, questions and scales must be presented thoroughly to facilitate comparisons and the results should be interpreted with caution. Today there are no reasons to use such instruments in the ERI model. One statement in the ERI model is that individuals with the coping behaviour characterised as WOC are particularly vulnerable to an imbalance between perceived effort and reward; i.e., that ERI and WOC interact. No such effect was shown in relation to disturbed sleep and fatigue. There is no convincing evidence that ERI and WOC interact in synergy. Analysis demonstrated that WOC was relatively stable in perceived unchanged conditions as measured by the original, more comprehensive instrument as well as by the present, shortened instrument. Positively or negatively perceived changes in ERI correspond to changes in WOC. This result suggests that WOC, at least in part, may act as not only a coping strategy but also as an outcome from ERI. Taken together, these results concerning WOC, suggest that studies to clarify the role of the WOC dimension are needed. The ERI model states that, when individuals stay in unfavourable conditions characterised as ERI, because there are few alternatives on the labour market or when the individual is at risk of being laid off or of facing downward mobility, they are in a “locked in position” (LIP). A strong association between LIP and ERI was shown, supporting this statement.