Effects of occupational stress and mental health on work-related musculoskeletal disorders in coal mine workers in Xinjiang

Background The occurrence of musculoskeletal disorders in coal mine workers remains high, and psychological factors are one of the important factors.

Objective To explore the occupational stress level, mental health status, and prevalence of work-related musculoskeletal disorders (WMSDs) of coal miners in Xinjiang, and to analyze the effects of occupational stress and mental health on WMSDs.

Methods From August 2018 to August 2019, 1300 workers of 4 coal mines were selected by cluster sampling method. Musculoskeletal Disorders Questionnaire, Effort-Reward Imbalance (ERI) Scale, Self Reporting Inventory (SCL-90) were used to investigate the prevalence of WMSDs, occupational stress, and mental health.

Results A total of 1177 valid questionnaires were collected, with a valid rate of 90.5%. The prevalence rate of WMSDs was 66.4%, the positive rate of occupational stress was 50.2%, and the positive rate of psychological symptoms was 53.4%. The M (P₂₅, P₇₅) ERI score was 1.0 (0.9,1.2), and the M (P₂₅, P₇₅) SCL-90 score was 138.0 (117.0,184.0). The prevalence rate of WMSDs in ≥3 sites was 45.0% in the occupational stress group and 46.0% in the positive psychological symptoms group. The results of binary logistic regression analysis showed that reporting occupational stress (OR=1.835, 95%CI: 1.380-2.440) and positive psychological symptoms (OR=1.461, 95%CI: 1.083-1.969) were positively associated with the prevalence of WMSDs; those being female (OR=2.393, 95%CI: 1.544-3.709), aged≥30 years (OR_30-＜40=2.344, 95%CI: 1.507-3.645; OR_40-＜50=2.395, 95%CI: 1.541-3.723; OR_50-60=5.115, 95%CI: 2.872-9.111), with length of service>15 years (OR=2.283, 95%CI: 1.537-3.392), and being coal diggers (OR=1.591, 95%CI: 1.070-2.365) showed higher risks of reporting WMSDs; those with education level at high school and above (OR_{high school}=0.399, 95%CI: 0.279-0.571; OR_{college and above}=0.220, 95%CI: 0.157-0.310), and monthly income>8000 yuan (OR=0.364, 95%CI: 0.227-0.582) showed lower risks of reporting WMSDs. The results of structural equation model showed that in model 1 with mental health as the intermediate variable, occupational stress and mental health directly affected WMSDs, and the standardized path coefficients (β) were 0.10 and 0.25 respectively; ERI also directly affected mental health with a β of 0.20. In model 2 with WMSDs as the intermediate variable, ERI and WMSDs directly affected mental health, and the β values were 0.16 and 0.25 respectively; ERI also directly affected WMSDs with a β of 0.16.

Conclusion The prevalence rate of WMSDs in selected coal mine workers is high, and occupational stress and mental health affect the occurrence of WMSDs.