A Scoping Review of the Effort-Reward Imbalance Model Applied to Musculoskeletal Symptom Outcomes

The effort-reward imbalance (ERI) model can provide valuable insights into musculoskeletal symptom (MSS) outcomes for workers, which may inform the development and implementation of interventions to reduce the burden of workers' MSS. The ERI model is comprised of effort and reward variables, as well as three reward sub-scales (promotion opportunities, job security and esteem). The model has three hypotheses: the ERI, overcommitment, and ERI*overcommitment interaction hypotheses. In this scoping review, we determine how the ERI model applies to MSS outcomes. Specifically, we considered which variables had been investigated (e.g. effort, ERI ratio), and which of the three hypotheses had been investigated. We also explored which variables in the ERI model are associated with MSS outcomes. Through a systematic search, we identified 50 relevant studies. Only two studies investigated all three ERI model hypotheses, indicating that little is known about how the model as a whole operates with regard to MSS outcomes. The ERI hypothesis was investigated in 13 studies, the overcommitment hypothesis in 24, and the ERI*overcommitment interaction hypothesis in six. The findings regarding the association between ERI elements and MSS outcomes were inconsistent both within (e.g. for different sub-groups, and/or different MSS outcomes) and between studies. The application of the ERI model as a whole to MSS outcomes has not been investigated sufficiently. Although specific hypotheses have been investigated, these studies were of diverse occupational groups, and generalisability of findings across such diverse occupational groups cannot be assumed. Understanding the relationship between each specific variable of the ERI model, as well as the three hypotheses, and MSS outcomes may lead to more specific recommendations to reduce the burden of workers' MSSs.