Job stress and chronic low back pain: incidence, number of episodes, and severity in a 4-year follow-up of the ELSA-Brasil Musculoskeletal cohort

Abstract We investigated the association between job stress, as assessed by the effort–reward imbalance model, and the incidence of chronic low back pain (CLBP) over a 4-year period. A total of 1733 participants from the ELSA-Brasil Musculoskeletal cohort, who were free from LBP at baseline (2012-2014), were included. Episodes of LBP in the past 30 days, intensity, and the presence of disability were investigated in annual telephone follow-ups (2015-2018). Chronic LBP was defined as episodes of LBP lasting >3 months with at least moderate intensity. We analyzed the incidence of at least one episode of CLBP (yes/no), the number of CLBP episodes (0, 1, ≥2), and CLBP severity/disability (absent, nondisabling, severe/disabling). The association between these outcomes and tertiles of the effort-to-reward ratio, as well as each dimension of the effort–reward imbalance model, was investigated using multinomial logistic and Poisson regression models adjusting for sociodemographic and occupational variables. The cumulative incidence of CLBP over 4 years was 24.8%. High effort–reward imbalance increased the chances of experiencing multiple CLBP episodes and severe/disabling CLBP by 67% (95% confidence interval [CI]: 1.12-2.47) and 70% (95% CI: 1.14-2.53), respectively. High overcommitment increased the incidence of CLBP by 23% (95% CI: 1.01-1.50) and the chances of multiple CLBP episodes and severe/disabling CLBP by 67% (95% CI: 1.11-2.50) and 57% (95% CI: 1.05-2.34), respectively. These results indicate that exposure to job stress is associated with a higher incidence, a greater number of episodes, and increased severity of CLBP over a 4-year period. If this association is causal, measures aimed at reducing exposure to job stress are likely to alleviate the burden of CLBP.