Exposure-response relationships for work-related neck and shoulder musculoskeletal disorders--Analyses of pooled...

There is a lack of quantitative data regarding exposure-response relationships between occupational risk factors and musculoskeletal disorders in the neck and shoulders. We explored such relationships in pooled data from a series of our cross-sectional studies. We recorded the prevalence of complaints/discomfort (Nordic Questionnaire) and diagnoses (physical examination) in 33 groups (24 female and 9 male) within which the workers had similar work tasks (3141 workers, of which 817 were males). In representative sub-groups, we recorded postures and velocities of the head (N = 299) and right upper arm (inclinometry; N = 306), right wrist postures and velocities (electrogoniometry; N = 499), and muscular activity (electromyography) in the right trapezius muscle (N = 431) and forearm extensors (N = 206). We also assessed the psychosocial work environment (Job Content Questionnaire). Uni- and multivariate linear meta-regression analysis revealed several statistically significant group-wise associations. Neck disorders were associated with head inclination, upper arm elevation, muscle activity of the trapezius and forearm extensors and wrist posture and angular velocity. Right-side shoulder disorders were associated with head and upper arm velocity, activity in the trapezius and forearm extensor muscles and wrist posture and angular velocity. The psychosocial work environment (low job control, job strain and isostrain) was also associated with disorders. Women exhibited a higher prevalence of neck and shoulder complaints and tension neck syndrome than men, when adjusting for postures, velocities, muscular activity or psychosocial exposure. In conclusion, the analyses established quantitative exposure-response relationships between neck and shoulder disorders and objective measures of the physical workload on the arm. Such information can be used for risk assessment in different occupations/work tasks, to establish quantitative exposure limits, and for the evaluation of preventive measures.