Survey And Analysis On Risk Factors Of Musculoskeletal Disorders Among Automobile Manufacturing Workers

Background In many developed countries, MSDs are a major problem of occupational health and an economic burden. MSDs account for a main component of the cost of work-related diseases in the United States. Recent evaluation of the cost related to MSDs varied from$13to$54billion annually. Some features of automobile manufacturing are just the risk factors of MSDs, such as rapid work pace and repetitive movement, forceful exertions, non-neutral postures (either dynamic or static), mechanical pressure, vibration; Since2009, China has been the largest automobile manufacturing country in the world. However, the automation degree and ergonomic conditions of auto industry in the country were far lower than in developed countries. The automobile manufacturing workers of China may suffer from more unreasonable working conditions. Previous studies conducted among automobile industry workers, due to cover less potential risk factors of MSDs, could not illustrate to the point the overall effect of occupational risk factors to MSDs, and therefore the comparison of the risk factors was limited. This study was aimed to examine the prevalence of MSDs and its potential risk factors among Chinese automobile industry workers, and provide the basis of intervention measures for the disorders.Method A total of1566automobile industry workers as subjects were investigated in a cross-sectional study. The questionnaire was developed according to the Dutch Musculoskeletal Questionnaire (DMQ) and the Nordic Musculoskeletal Questionnaire (NMQ). Data analysis:The prevalence of MSDs was calculated for each group classified by individual factors. Differences of prevalence between these groups were determined using chi-square tests. Univariate logistic regressions were used to estimate the crude odds ratios (ORs) of each potential risk factor. The individual factors with statistical significance were taken into account as potential confounders to estimate the adjusted ORs in each multivariate logistic regression model. Finally, multivariate logistic regression models were developed for MSDs of low back, neck and knee.Results (1) The MSDs occurred primarily in low back and neck, with annual prevalence of66.5%and57.4%, respectively.(2) The adjusted ORs of risk factors were calculated using logistic regression analysis. The main findings were as follows: lifting heavy loads(more than5kg) had positive impact on MSDs of neck, low back and knee, with ORs1.4,1.7and1.4respectively; prolonged standing increased the risk of MSDs in neck, low back and knee(OR:1.5,2.1, and1.6, respectively), whereas only the "always" category of squatting or kneeling can impose an significant effect on MSDs of knee; personnel shortage had a positive association with MSDs of neck, low back and knee(OR:1.8,1.5and1.6, respectively), while breaks at work decrease the risks to90%,80%and60%for MSDs of neck, low back and knee separately. Job title had no significant association with MSDs of neck and knee, but the prevalence of MSDs for low back significantly higher among welder and machining workers than maintainers; repetitive movement per minute also significantly associated with MSDs in neck, low back, and knee(OR:1.6,2.1and1.5, respectively); Having no enough room increase the risk of MSDs in neck, low back, and knee(OR:1.6,1.8and1.7, respectively).(3) Multivariate logistic regression models showed that the main risk factors for MSDs of low back were gender, age, neck in a bent forward posture for long periods, holding the hands at or under shoulder level, working in uncomfortable postures, prolonged squatting, lifting with uncomfortable position, repetitive movement of trunk, repetitive movement per minutes, Slipping or falling during work, driving, working in the same workshop, while the protective was having sufficient normal breaks.(4) Multivariate logistic regression models showed that the main risk factors for neck MSDs were gender, age, years of service, smoking, prolonged walking, neck in a bent forward posture for long periods, neck twisted for long periods, working in uncomfortable postures, lifting in uncomfortable position, coldness, driving, having to replace colleagues often.(5) Multivariate logistic regression models showed that the main risk factors for knee MSDs were age, years of service, working in uncomfortable postures, prolonged standing, lifting with single hand, Slipping or falling during work, coldness, carrying out the same work almost every day, working hours per week. Conclusions (1) Lifting very heavy loads(more than20kg) had a closer relationship with MSDs of low back than with that of neck or knee, while lifting relatively light loads(more than5kg) had no significant impact on neck and knee.(2) prolonged standing increased the risk of MSDs of neck, low back and knee, while only the "always" category for squatting and kneeling imposed a significant influence on knee.(3) Work organization had an important impact on the occurrence of MSDs; adding personnel and increasing breaks at work should be considered to decrease the prevalence of MSDs.(4)repetitive movements, carrying the same task every day significantly increase the risk of MSDs.(5) Ergonomic environmental factors have important influences on MSDs, and more attention should be imposed on it.