A systematic review and meta-analysis of the effort-reward imbalance model of workplace stress with indicators of immune function.

Objective: Despite considerable research into associations between the effort reward imbalance (ERI) model and various health outcomes over the past 20years, the underlying mechanisms responsible for the association remain unclear. Recently, ERI investigations have examined associations with immune sub-systems (e.g., leukocytes, cytokines and immunoglobulins). Synthesis of the amalgamated research evidence will aid clarity to this field of enquiry. We conducted a meta-analysis and reviewed the associations of ERI and over-commitment (OC) in the workplace with immunity.

Method: Electronic databases were searched with the phrase 'effort reward imbalance' which initially yielded 319 studies leading to 57 full text studies being screened. Seven studies that met inclusion criteria were combined using mixed and random effects models.

Results: Greater ERI was associated with lower immunity (r=-0.09, CI -0.14, -0.05, p<0.001). Sub-group analyses revealed the effect with mucosal immunity was stronger (r=-0.33, CI -0.47 to -0.18) than trends between both cytokine (r=-0.04, CI -0.07, -0.01) and leukocyte sub-groups (r=-0.02 CI -0.04, 0.01) respectively (k=7, N=9952). Over-commitment was also associated with lower immunity (r=-0.05, CI -0.09, 0.01, p=0.014); subgroup (leukocytes, cytokines, mucosal immunity) associations, however, were homogenous (Q=1.83, df=2, p=0.400, k=6, N=2358).

Conclusions: Greater ERI and OC were both associated with lower immunity. The association between mucosal immunity and ERI was stronger than the cytokine and leukocyte sub-groups. OC moderated the relationship between ERI and immunity.