Reviewing the effort–reward imbalance model: drawing up the balance of 45 empirical studies
Introduction
Occupational health researchers have tried to gain more insight into the relationship between work characteristics and employee health. With the help of work stress models they attempt to reduce the complex reality into comprehensive and parsimonious models, highlighting some core elements in order to explain job-related health. One of the most important models that has recently guided occupational health research is the Effort–Reward Imbalance (ERI) Model (Siegrist, 1996; Siegrist, Siegrist, & Weber, 1986). The ERI Model has its origin in medical sociology and emphasizes both the effort and the reward structure of work (Marmot, Siegrist, Theorell, & Feeney, 1999). The model is based upon the premise that work-related benefits depend upon a reciprocal relationship between efforts and rewards at work. Efforts represent job demands and/or obligations that are imposed on the employee. Occupational rewards distributed by the employer (and by society at large) consist of money, esteem, and job security/career opportunities. More specifically, the ERI Model claims that work characterized by both high efforts and low rewards represents a reciprocity deficit between “costs” and “gains”. This imbalance may cause sustained strain reactions. So, working hard without receiving appreciation is an example of a stressful imbalance. In addition, it is assumed that this process will be intensified by overcommitment (a personality characteristic), such that highly overcommitted employees will respond with more strain reactions to an ERI, in comparison with less overcommitted employees.
Over the past years, the ERI Model has gained popularity (especially in European research), and numerous studies have applied the model to various health outcomes. Although the number of ERI studies rose steadily, a detailed review evaluating those studies is to our knowledge still lacking. The present study tries to fill this gap by presenting a review of empirical studies testing the ERI Model. Since the ERI Model has considerably evolved over time and some studies might have been designed from a previous/different perspective of the model, it is necessary to get more familiar with the background of the model. Hence, we will give a short historical overview of the most relevant developments that preceded the model in its current form.
In 1986, a sociological framework being the ERI Model was introduced by Siegrist et al. (1986) to predict and explain (the onset of) cardiovascular-related outcomes. The ERI Model claims that the work role is crucial in order to fulfill individual self-regulatory needs. That is, work offers opportunities to acquire self-efficacy (e.g., successful performance), self-esteem (e.g., recognition) and self-integration (e.g., belonging to a significant group). Based on the principle of social exchange (i.e., reciprocity), the employee invests efforts and expects rewards in return. However, in case an imbalance is present between high effort and low reward, this taken-for-granted routine is disrupted and the fulfillment of the self-regulatory needs is threatened. According to Siegrist et al. (1986) this imbalance may lead to a state of “active distress” by evoking strong negative emotions, which in turn activate two stress axes, i.e., the sympathetic-adrenomedullary and the pituitary–adrenal–cortical system (Henry & Stephens, 1977). In the long run, sustained activation of the autonomic nervous system may contribute to the development of physical (e.g., cardiovascular) and mental (e.g., depression) diseases (see also Weiner, 1992).
In its premature years, the ERI Model was primarily used to investigate cardiovascular outcomes. It was not until 1998 that the model was applied to other psychological and behavioral outcomes as well. Appels can be considered as a pioneer in linking ERI (i.e., high effort and low reward) to psychological outcomes such as vital exhaustion (Appels, Siegrist, & Vos, 1997). Appels’ work (Appels & Schouten, 1991) showed that vital exhaustion may lead to acute myocardial infarction (AMI). In addition, he found strong independent effects of ERI and vital exhaustion on AMI (Appels, Siegrist, & Vos, 1997). Those results suggest that ERI could lead to cardiac events, but also that this relation might be mediated by vital exhaustion. Implicitly, the ERI Model can also be considered as predictive for psychological well-being, as ERI evokes strong negative emotions, which are related to impaired well-being (cf. Gaillard & Wientjes, 1994). Furthermore, it has been argued that the model can be applied to addictive behavior as well. According to Blum, Cull, Braverman, and Comings (1996), prolonged stress leads to dysfunction or disruption of the mesolimbic dopamine system, which in turn stimulates addictive behavior. To summarize, an ERI seems to evoke adverse health by stimulating neuro-biological, psychological and behavioral pathways.
In general, the idea prevails that people will not passively stay in a high-effort–low-reward imbalance situation, but that they will try to cognitively and behaviorally reduce their efforts and/or maximize their rewards (e.g., cognitive theory of emotion (Lazarus, 1991) and expectancy theory of motivation (Schönpflug & Batman, 1989)). Hence, an ERI might not influence health over a longer period. But according to Siegrist (1996), negative effect associated with ERI may not be consciously appraised, as it is a chronically recurrent everyday experience (cf. Gaillard & Wientjes, 1994). Furthermore, Siegrist (1996) identified some specific circumstances under which a high cost/low gain condition is maintained: (1) when there is no alternative choice on the labor market, (2) for strategic reasons (e.g., expecting future gains), and (3) when the employee is characterized by a motivational pattern of excessive work-related overcommitment. Overcommitment is seen as a personality characteristic based on the cognitive, emotional and motivational elements of Type A behavior that reflect an exorbitant ambition in combination with the need to be approved and esteemed (Hanson, Schaufeli, Vrijkotte, Plomp, & Godaert, 2000; Siegrist, 1998). Overcommitment can be defined as the person-specific component, whereas efforts and rewards compromise the situation-specific component.
To measure the key concepts of the ERI Model, information was gathered from different sources, i.e., contextual information (such as administrative data and objective measures), descriptive and evaluative information (through interviews and questionnaires). A combination of those sources was mainly used to measure effort and reward. Overcommitment was solely assessed by a questionnaire (cf. Matschinger, Siegrist, Siegrist, & Dittmann, 1986). Subsequently, a questionnaire was developed to measure all components of the ERI Model, i.e., effort, reward and overcommitment. The introduction of this so-called ERI Questionnaire (ERI-Q; (Siegrist & Peter, 1996a) led to a predominant use of questionnaires to test the ERI Model.
The effort scale in the ERI-Q contains six items of which the content varies from physical load, time pressure, interruptions, responsibility, working overtime to increasing demands. Siegrist et al. (2004) have recommended to include the item on physical load only in those occupational groups where prevalence of physical workload is part of the typical task profile. Reward in the ERI-Q has been operationalized by means of 11 items, and is usually measured as a composite measure. Theoretically, a three-factor structure underlies the concept of reward (i.e., money, esteem and security/career opportunities). Recent studies confirm the presence of the three-factorial structure (Siegrist et al., 2004), and the importance of splitting three types of rewards (Dragano, Knesebeck, Rödel, & Siegrist, 2003; van Vegchel, de Jonge, Bakker, & Schaufeli, 2002). The operationalization of overcommitment has considerably changed over time. Originally, overcommitment was operationalized by the scale “need for control”, as a more work-related reformulation of the Type A concept (cf. Matschinger et al., 1986). The need for control scale contains two latent factors: vigor and immersion. Vigor refers to successful coping (by perfectionism and hard work). Immersion defines a critical state of coping with demands reflecting frustrated, but continued efforts and associated negative feelings. Immersion consists of four subscales: (a) need for approval, (b) competitiveness, (c) disproportionate irritability, and (d) inability to withdraw from work (Siegrist, 1996). Although some empirical studies were able to replicate the factorial structure of immersion (e.g., Peter et al., 1998), other studies could not replicate the respective factorial structure, and showed that especially the factor “inability to withdraw from work” was essential for the ERI Model (see Hanson et al., 2000; Niedhammer, Siegrist, Landre, Goldberg, & Leclerc, 2000). Therefore, a shorter version was developed to represent overcommitment, mainly consisting of inability to withdraw from work (five items) and one item of disproportionate irritability (Siegrist et al., 2004).
Despite developments in their operationalization over time, the concepts effort, reward and overcommitment remained the core components of the ERI Model. Graphical representations of the original version and the current version of the ERI Model are shown in Fig. 1, Fig. 2, respectively. As can be seen, two concepts have been relabeled: “intrinsic effort/need for control” into “overcommitment”, and “status control” into “security/career opportunities”. Reasons for this are not reported in the literature.
The most profound change in Fig. 1, Fig. 2 comprises the role of overcommitment. According to Fig. 1, overcommitment is part of effort. Because highly overcommitted employees underestimate challenging situations and overestimate their own capability, they tend to invest (too) many efforts. Therefore, the amount of effort invested is dependent upon both extrinsic (i.e., demands and obligations from work) and intrinsic (i.e., overcommitment) efforts. So, the main assumption of the ERI Model was that a mismatch between high extrinsic or intrinsic efforts and low reward may lead to an adverse health. Later, as shown in Fig. 2, overcommitment is seen as an independent concept. Overcommitment influences the perception of both high efforts and low reward, and therefore influences employee health indirectly. In addition, overcommitment is thought to have a direct effect on employee health as well, as being highly overcommitted (i.e., involved with work all the time) might be exhaustive in the long run.
Based upon this line of reasoning, Siegrist (2002) has formulated three predictions that can be postulated for the ERI Model. Firstly, the extrinsic ERI hypothesis: an imbalance between (high) extrinsic effort and (low) reward increases the risk of poor health, over and above the risks associated with each one of the components (i.e., high efforts and low rewards). Secondly, the intrinsic overcommitment (OVC) hypothesis: a high level of overcommitment, possibly resulting in continued exaggerated efforts combined with disappointing rewards, may also increase the risk of poor health (even in the absence of an extrinsic ERI, i.e., a main effect of overcommitment). And finally, the interaction hypothesis (i.e., ERI×OVC): an extrinsic ERI in combination with a high level of overcommitment leads to the highest risk of poor health. Therefore, a complete test of the ERI Model covers all three conditions mentioned (i.e., effort, reward and overcommitment).
Due to changes in the concepts and their operationalizations, studies may differ in their design of the study. For instance, some studies might have included overcommitment into the effort concept, and studies might differ in the labels they used for several concepts. The three hypotheses (i.e., ERI, OVC, and ERI×OVC) mentioned above will guide the current review of the ERI Model, as they are consistent with the most recent view of the model. However, we are aware that the development of the ERI Model has its influence on the study. Therefore, we will systematically consider the amount of support that is found for each hypothesis, taking into account the development through time.
Section snippets
Studies included in the review
Since the current review might be the first review for the ERI Model, the present review tries to encompass as much empirical studies as possible. Inspection of the ERI studies showed that most studies used (logistic) regression analyses in which variables are examined in a particular composition (for instance including socio-demographic variables), which complicates revealing the unique contribution of the ERI variables (as would be necessary for a meta-analysis). As many studies would have to
Review results
Table 1 summarizes the ERI studies for each hypothesis per outcome category. Note that the ERI hypothesis has been divided into three different columns (i.e., all efforts included into an ERI index regardless of the type of effort used, an ERI index containing only extrinsic efforts, an ERI index including at least intrinsic effort—combined with or without extrinsic efforts) to give a more accurate reflection of the specific ERI hypothesis under study. Due to previous definitions of the ERI
Discussion
The present review balanced the results of 45 empirical studies published from 1986 up to and including 2003 with respect to the ERI Model. Taking the development of the ERI Model into account, the model was evaluated on the basis of evidence for three hypotheses (cf. Siegrist, 2002). Firstly, the (extrinsic) ERI hypothesis which assumes that employees with high efforts and low rewards at work will have a higher risk of poor health. Secondly, the OVC hypothesis which maintains that employees
Acknowledgement
The current study is part of the research program on “Fatigue at Work” by NWO, the Dutch Organisation for Scientific Research (Grant 580-02-209).
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