Study design: Cross-sectional study.
Objectives: To evaluate the effect of individual characteristics and physical and psychosocial workplace factors on neck/shoulder pain with pressure tenderness in the muscles.
Summary of background data: Controversy prevails about the importance of workplace factors versus individual factors in the etiology of pain in the neck and/or shoulders.
Methods: Study participants were 3123 workers from 19 plants. Physical risk factors were evaluated via video observations, and psychosocial risk factors were assessed with the job content questionnaire. Other procedures included symptom survey, clinical examination, and assessment of health-related quality of life (SF-36). The main outcome variable, neck/shoulder pain with pressure tenderness, was defined on the basis of subjective pain score and pressure tenderness in muscles of the neck/shoulder region.
Results: The prevalence of neck/shoulder pain with pressure tenderness was 7.0% among participants performing repetitive work and 3.8% among the referents. We found an association with high repetitiveness (prevalence ratio 1.8, 95% confidence interval 1.1-2.9), high force (2.0, 1.2-3.3), and high repetitiveness and high force (2.3, 1.4-4.0). The strongest work-related psychosocial risk was high job demands (1.8, 1.2-2.7). Increased risk was also associated with neck/shoulder injury (2.6, 1.6-4.1), female gender (1.8, 1.2-2.8), and low pressure pain threshold (1.6, 1.1-2.3). Neck/shoulder pain was strongly associated with reduced health-related quality of life.
Conclusions: Work-related physical and psychosocial factors, as well as several individual risk factors, are important in the understanding of neck/shoulder pain. The findings suggest that neck/shoulder pain has a multifactorial nature. Reduced health-related quality of life is associated with subjective pain and clinical signs from the neck and shoulders. The physical workplace factors were highly intercorrelated, and so the effect of individual physical exposures could only be disentangled to a minor degree.