Longitudinal evidence for the association between work-related physical exposures and neck and/or shoulder complaints: A systematic review

Background: Most existing reviews focus on evidence for the association between neck and/or shoulder complaints and physical exposures at the workplace gathered from cross-sectional studies. In comparison, this review summarizes existing evidence from longitudinal studies only. Methods: A systematic literature research was conducted in Medline and EMBASE (1975-2009), and all studies were scanned by at least two researchers according to strict inclusion criteria. Levels of evidence were assigned according to the number of studies reporting similar findings, and according to the methodological quality of the included studies. Results: Altogether 21 longitudinal studies (19 highquality studies) met the inclusion criteria and were included in this review. In comparison with former reviews, we found strong evidence for an association between shoulder complaints and manual material handling (MMH) (range between Odds Ratio (OR) 1.4 and 4.9), vibration (range between OR 1.6 and OR 2.5), trunk flexion or rotation (range between OR 1.8 and OR 5.1), and working with hands above shoulder level (range between OR 1.1 and OR 1.8). Apart from that, the included studies confirmed existing knowledge on the association between physical exposures at the workplace and neck and/or shoulder complaints. Conclusions: This analysis of longitudinal studies allowed for new evidence with regard to four cause-effect chains between physical exposures at work and the development of shoulder, neck and neck/shoulder complaints. As outcome variables varied greatly among the included studies, harmonization in studies on musculoskeletal research is desirable.