[Structural equation analysis of the incidence of shoulder WMSDs and individual and work-related factors]

Objective: To investigate the incidence of shoulder work-related musculoskeletal disorders (WMSDs) among occupational population in China, and to explore their intrinsic association with personal and work-related factors. Methods: In April 2024, 73497 valid questionnaires of the Chinese version of the Musculoskeletal Disorders Electronic Questionnaire were retrospectively analyzed from June 2018 to December 2023 in 22 provinces and 29 key industries in China, and the general information, occurrence of WMSDs and related risk factors of key occupational populations in different regions in China were collected. By using Chi-square test and confirmatory factor analysis, the relationship between shoulder fatigue and pain in key occupational groups and individual factors, work type, work posture and work organization was discussed, and the internal relationship was analyzed based on structural equation model. Results: Higher incidence of shoulder fatigue and pain were associated with female, lack of physical exercise, uncomfortable working posture and neck leaning forward (P<0.05). Structural equation model analysis showed that work type, work posture and work organization were strongly correlated (r=0.58, 0.55). Work organization and work type were strongly correlated with shoulder fatigue (r=0.65) and moderately correlated with shoulder fatigue (r=0.21). Shoulder fatigue was moderately associated with shoulder pain (r=0.40). Individual factors, work type, work posture and shoulder fatigue could directly affect shoulder pain (OR=0.07, -0.09, 0.17 and 0.40), and work type and work posture could also indirectly affect shoulder pain through shoulder fatigue (OR=0.08, 0.03). Work organization only indirectly affected shoulder pain through shoulder fatigue (OR=0.26) . Conclusion: The main influencing factor of shoulder pain is shoulder fatigue, followed by work posture and individual factors. Structural equation model can better reflect the complex relationship between work type, work posture and work organization and shoulder WMSDs. Improving work posture and work organization may be an effective way to control the influence of shoulder fatigue on shoulder pain.