The incremental effect of psychosocial workplace factors on the development of neck and shoulder disorders: A systematic review of longitudinal studies

Background To systematically analyse evidence on the incremental effect of work-related psychosocial risk factors on the development of neck and shoulder disorders, as reported in longitudinal studies. Methods A systematic literature search was conducted in three data bases (MEDLINE, EMBASE, and PsychINFO) until May 2009. The quality assessment leading to a methodological quality score of the included studies was conducted by two independent reviewers using a standardised checklist. Criteria for the evaluation of evidence were established. Heterogeneity analyses were conducted. Results Altogether 18 prospective longitudinal studies were included in the analysis. Potential psychosocial risk factors were mainly based on the job demand control (support) model by Karasek (1998). Study results were too heterogeneous to deduce pooled risk estimates. But the weight of evidence was strong for an incremental effect of job demands, job control, social support, and job strain, on the development of neck and/or shoulder disorders. Conclusion While we found evidence for an incremental effect of different psychosocial work factors (in addition to the effect of physical job factors), these results have to be interpreted carefully in order to support the notion that psychological factors can have an independent causal influence on the development of musculoskeletal disorders. Nevertheless, our findings are important for the development of preventive strategies, as they stress the need for preventive approaches that tackle both physical and psychosocial factors. Future research is warranted to consolidate and strengthen the results of this review.