Background In the process of greenhouse working, labor intensity is high and repetitive work involves multiple body parts such as limbs, neck, upper back, and lower back. The prevalence and comorbidity of work-related musculoskeletal disorders (WMSDs) in greenhouse workers are worthy of attention.
Objective This study is conducted to investigate the prevalence and comorbidity, as well as potential influencing factors of WMSDs in greenhouse workers.
Methods A total of 722 greenhouse workers were selected as the subjects for a cross-sectional epidemiological survey. Through questionnaire survey and physical examination, basic information of the subjects and the prevalence of WMSDs were collected. The participants were divided into low, medium, and high cumulative exposure groups by cumulative exposure index matrix. Chi-square test was used to analyze the difference of prevalence among different cumulative exposure levels, the correlation between the prevalence of WMSDs in paired sites was calculated as prevalence ratio (PR) by using the log-binomial model, the prevalence of multi-site WMSDs in each group was compared by Wilcoxon rank sum test, and the influencing factors of multi-site WMSDs were evaluated by multi-classification logistic regression model.
Results The prevalence rate of WMSDs in the greenhouse workers was 78.7% (568/722). The main affected sites of body were lower back, legs, neck, and shoulders, and associated prevalence rates were 47.6%, 46.0%, 27.1%, and 23.8%, respectively. By constructing a cumulative exposure index matrix, the low, medium, and high cumulative exposure groups contained 121, 196, and 405 workers respectively. The prevalence rates of WMSDs in lower back, legs, or shoulders were significantly different among groups with different exposure levels (
P<0.05), and the prevalence rates increased with higher cumulative exposure levels (lower back,
χ _\rmtrend ^2
=11.144,
P<0.05; legs,
χ _\rmtrend ^2 =6.767,
P<0.05; shoulders,
χ _\rmtrend ^2 =15.666,
P<0.05). The results of log-binomial model found that lower back and legs (
PR values were 1.57 and 1.43, respectively) as well as neck and shoulders (
PR values were 2.00 and 2.07, respectively) among the main affected parts have a strong association with comorbidities. The prevalence of multi-site WMSDs showed that 50.4% of the workers had comorbidity of two or more sites of WMSDs. The results of multi-classification logistic regression analysis indicated that the influencing factors of WMSDs in two sites involved high-level cumulative exposure (
OR=2.41, 95%
CI: 1.34-4.33) and female (
OR=3.27, 95%
CI: 2.07-5.16); the influencing factors of WMSDs in three or more sites also included medium-level cumulative exposure (
OR=3.78, 95%
CI: 1.70-8.39), high-level cumulative exposure (
OR=7.34, 95%
CI: 3.41-15.80), and female (
OR=5.66, 95%
CI: 3.48-9.22).
Conclusion In this study, the prevalence rates of WMSDs in lower back, legs, neck, and shoulders are high among selected solar greenhouse workers, and WMSDs comorbidity of lower back-legs and neck-shoulders are identified. Greenhouse workers with high cumulative exposure level and female workers report more WMSDs comorbidities in two or more sites.
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