Risk Factors for Musculoskeletal Symptoms in Sewing Tasks

Title:

Work-related psychosocial, physical and sociodemographic risk factors for musculoskeletal symptoms of the neck, shoulders and low back among workers engaged in sewing tasks

Abstract

Background: Neck/shoulder and back pain are highly prevalent among workers engaged in sewing activities, but their risk factors are controversial or not well-established.

Methods: Data on sociodemographic and work-related factors and musculoskeletal pain (MSP) were based on questionnaire surveys of Iranian sewing workers (n = 632) (i.e. carpet weavers, shoe workers and sewing machine operators).

Results: The prevalence of neck, shoulder and low back pain was 57.9%, 40.5% and 51.6%, respectively. The prevalence of neck/shoulder pain was higher among females and with increasing age. Working posture and fast working were independently associated with neck, shoulder and low back pain. Number of years worked as a sewing worker was associated with neck and low back pain. Long duration of continuous sitting work without a break was only associated with neck pain.

Conclusions: The findings emphasise the importance of individual, physical and psychosocial aspects of sewing tasks in association with MSP and highlight the role of prevention in the workplace in order to reduce MSP.

Keywords: hand-sewn; shoemaking; carpet weaving; sewing machine; MSDs

Introduction

Musculoskeletal pain (MSP) in the low back and neck/shoulders is a common cause of reduced quality of life, sick leave, and work disability in both industrialized and industrially developing countries (van der Windt et al. 2000; Picavet and Schouten 2003; McBeth and Jones 2007; Dianat and Salimi 2014). The risk and protective factors of these pains among different occupational groups, particularly in those involved in sedentary and repetitive activities, can be divided into physical, psychosocial, organizational and sociodemographic factors (Ariëns et al. 2000; van der Windt et al. 2000; Linton 2001; Côté et al. 2008; Dianat and Salimi 2014).

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Evidence suggests that neck/shoulder and back pain are highly prevalent among workers engaged in sewing activities. Previous epidemiological studies have shown a high prevalence of neck/shoulder and back pain among sewing machine operators (Serratos-Perez and Mendiola-Anda 1993; Roquelaure et al., 2002; Öztürk and Esin 2011), hand-woven carpet weavers (Motamedzade and Moghimbeigi 2012; Nazari et al. 2012) and hand-sewn shoe workers (Dianat and Salimi 2014). Such tasks are typically highly repetitive, which are performed in a seated working posture for a long period of time. The operations usually require the operator to lean forward (with a forward inclined posture of both head and trunk) to see the point of operation and have better visual control of the task. Such a working condition can impose excessive physical load on the musculoskeletal system, and may eventually lead to the development of MSP in the neck/shoulder and back area.

Several previous studies have assessed MSP among occupations involving sewing operations such as shoe sewing machine operators (Serratos-Perez and Mendiola-Anda 1993; Roquelaure et al. 2002), garment sewing machine operators (Westgaard and Jansen 1992; Kaergaard and Andersen 2000; Öztürk and Esin 2011; Wang et al. 2007; Dianat et al. 2015), hand-woven carpet weavers (Motamedzade and Moghimbeigi 2012; Nazari et al. 2012) and hand-sewn shoe workers (Dianat and Salimi 2014), although the effects of risk factors are not consistent and conclusive. There are, for example, very few studies which have examined the association between working postures and MSP among sewing machine operators with some studies showing positive association (Dianat et al. 2015), while others show no association (Öztürk and Esin 2011). This also seems to be the case for other relatively similar occupations (i.e. carpet weaving and shoemaking) and their contributing risk factors. Therefore, to reduce musculoskeletal pain, there is a need to improve the understanding of the risk factors associated with such complaints among this working population. Further research in this area will help to better understand the nature of those jobs involving sewing operation and to develop corrective measures and intervention strategies for this population. It also contributes more evidence to the debate and has the potential to inform work practises in other developing societies with similar occupational groups.

The aim of the present study was to evaluate the occurrence of neck, shoulder and low back pain and their contributing sociodemographic and work-related (psychosocial and physical) risk factors among workers involved in different sewing activities. The intention was to place the discussion in a wider occupational context and use the findings to highlight areas that need more attention and to assist in introducing preventative measures and developing guidelines regarding safe working practices for those jobs involving sewing operation.

Methods

Study design and sample

This cross-sectional, descriptive-analytical study was conducted in three provinces (East Azerbaijan, Kermanshah and Kordestan) in the western part of Iran. The study population consisted of those workers engaged in different sewing activities including hand-woven carpet weavers, hand-sewn shoe workers and sewing machine operators. Data on the number of workers and workshops in the study area was obtained from the Iranian Ministry of Industries and Mines. There were about 14,000 hand-woven carpet weavers, 7,000 hand-sewn shoe workers and 5,000 sewing machine operators in the study area who worked at approximately 1800, 1700 and 500 different workshops, respectively. Sampling was done using a multi-stage random selection process. In the first stage, the required numbers of workshops, which included 60 workshops from each of the three different occupational groups, were selected randomly (using probability proportion to size sampling method). Using the same procedure, participants were then selected from these workshops. The participants were familiarised with the study procedure and their questions were answered by the investigators. They each signed a written informed consent form before participation in the study. The study protocol was approved by the ethical review committee of the Tabriz University of Medical Sciences.

Measures and data collection

The data were collected using both questionnaire and direct observation of the participants during their work. Arrangements were made and then investigators visited the selected workshops for data collection. The questionnaire, administered by interviewing the participants, was composed of items on sociodemographic characteristics, work-related psychosocial and physical risk factors and musculoskeletal pain in the last month. Working postures were assessed through direct observation of participants’ postures at their workstations using the Rapid Upper Limb Assessment (RULA) method (McAtamney and Corlett 1993).

Musculoskeletal pain

The questions on MSP were adapted from the standardised Nordic Musculoskeletal Disorders Questionnaire (Kuorinka et al. 1987). This questionnaire has been translated and revised into Persian language and has an established validity and reliability (Dianat et al. 2014; Dianat and Karimi, 2014). The participants were asked whether they had experienced pain in the neck, shoulders or low back lasting for more than 1 day during the previous month. The location of these anatomic areas was also demonstrated by a drawing in the questionnaire. The response alternatives were: No/Yes. Those participants who reported MSP in any of these body areas were asked to rate its severity using a scale of 1 – very low pain to 5 – very high pain. Disruption of normal activities due to MSP (No/Yes) was also included.

Sociodemographic and work-related factors

The sociodemographic details included age, gender, height, weight, body mass index (BMI as weight/height²), educational level (Illiterate, Primary school, Secondary school, and Diploma), marital status (Single, Married), being involved in regular sport and physical activities each week (for at least 30 min) (No/Yes) and smoking habits (No/Yes).

The questions regarding the work-related psychosocial and physical factors were based on prior knowledge and a literature review (Westgaard and Jansen 1992; Kaergaard and Andersen 2000; Wang et al. 2007; Öztürk and Esin 2011; Dianat and Salimi 2014) and included daily working hours, number of years worked as a sewing worker, having a second job (No/Yes), perceived speed of work (asking ‘Does your work require you to work very fast? No/Yes), duration of continuous work without a break (> 10 min) (asking ‘How many hours do you usually work without breaks (breaks > 10 min)?’), perceived pressure due to work (asking ‘Do you feel pressure due to work? No/Yes’) and job satisfaction based on the question: ‘How much are you satisfied with your job? Low, Moderate, High’. The questionnaire was tested in a pilot study on a sample of 65 participants in order to obtain feedback on the content, clarity and wording of the items of the questionnaire. The test-retest reliability (stability) of the items of the questionnaire was also good (Kappa coefficients ranged from 0.80 to 0.98).

Rapid Upper Limb Assessment (RULA) (McAtamney and Corlett 1993) was used to assess the working postures of operators at their workstations. The RULA is a reliable and validated observational method for assessing biomechanical and postural loading on the musculoskeletal system of operators which is known to contribute to MSP. This method gives a score for each body part, where combinations of individual scores for upper arm, lower arm and wrist are called score “A”, those for neck, trunk and leg give score “B”, and the final score is called “grand score” which indicates the musculoskeletal loading associated with the operator’s posture. The original version of RULA checklist has been translated and revised into the Persian language and has shown to be valid and reliable (Dianat and Salimi 2014). The observations and recordings of working postures were performed by two trained observers. The inter-rater reliability of the RULA scores was also found to be good (Kappa coefficients ranging from 0.82 to 0.99).

Statistical analysis

The analysis of the data was performed using SPSS software (version 17.0; SPSS, Chicago, IL, USA). Sociodemographic data and work-related characteristics of the study participants were tabulated. Logistic regression models with odds ratios (ORs) and 95% confidence intervals (CIs) were developed to estimate the effects. The relationship between prevalence rates and study variables (sociodemographic and work-related characteristics) was initially assessed using univariate binary logistic regression analysis. The variables in the logistic regression analyses included sociodemographic (age, gender, BMI, educational level, marital status, smoking and being involved in regular sport/physical activities each week) and work-related characteristics (daily working hours, number of years worked as a sewing worker, having a second job, perceived speed of work, duration of continuous work without a break, perceived pressure due to work and job satisfaction) as well as three RULA scores including RULA score A (arm/wrist score), RULA score B (neck/trunk/leg score) and final RULA grand score. Multiple logistic regression analysis (using backward stepwise procedure) was also performed to estimate the association between independent variables and the reported neck, shoulder and low back pain in the multivariate context. The study variables were theoretically of equal importance, and therefore an equal role was assigned for all of them in the regression models without any adjustment. The assumptions of the models (including the presence of outliers and collinearity) were checked and the fit of the models was confirmed by the Hosmer-Lemeshow goodness-of-fit test. P < 0.05 was considered as statistically significant.

Discussion

The aim of the present study was to evaluate the occurrence of MSP and their contributing risk factors among sewing workers in a wider occupational context. One of the main findings of the study was that the prevalence of MSP was considerably high among the study population with 76.2% of the sample reporting this, and of these 68% had more than one site of discomfort or pain. This finding provides further evidence that musculoskeletal pain and discomfort is a major problem in this group of workers. More than one-third of the respondents reported disruption of normal activities due to MSP. Individual factors including gender (being female), age (> 30 years old) and lower educational level were independently associated with the occurrence of MSP. Work-related variables such as the number of years worked as a sewing worker (> 20 years for the neck and > 10 years for the low back pain), duration of continuous sitting work (> 2 h) without a break, fast working and working postures were also found to be independently associated with the occurrence of MSP among sewing workers.

There were several notable findings regarding the relation of individual factors to MSP. The results of the present study indicated that gender was a significant factor for neck and shoulder complaints, so that females experienced such complaints more frequently than males. This is similar to the findings of Wang et al. (2007), who reported a higher prevalence of neck/shoulder pain in female sewing machine operators than in males. It was also shown that age was significantly positively associated with neck and shoulder pain. It has been acknowledged that better understanding of the task characteristics may provide an insight into the job (re)design to support the user needs of older working population in future (Stedmon et al. 2012). Moreover, the findings indicated that workers with a higher educational level were less likely to report shoulder and low back pain than other workers. This supports the finding of a study conducted among hand-sewn shoe workers (Dianat and Salimi 2014).

As shown in this study, working posture was an important risk factor for the neck, shoulders and low back pain among sewing workers. This finding provide further evidence that the sewing operations involve frequent head and trunk bending movements over the duration of the task, and therefore imposes unacceptable postural loading on the upper body and limbs. Our findings indicated that the RULA scores for the workers’ upper and lower arm/wrist scores (score A), neck/trunk/legs scores (score B), and the grand scores were relatively high. The relatively high RULA scores in this study highlights that the working postures of the workers were constrained by both the visual and the manual aspects of the sewing tasks, and that the design of the sewing workstations had a significant influence on the postures adopted. This emphasises that in most cases the workers’ postures at their workstations need to be investigated and some changes are required immediately. These findings are in part consistent with several previous reports of poor working postures (assessed by the RULA method) among workers involved in sewing machine operating (Öztürk and Esin 2011; Teodoroski et al. 2012; Dianat et al. 2015) or hand-sewn shoemaking tasks (Dianat and Salimi 2014).

The results also suggest that there is a need to consider other work-related physical and psychosocial aspects of sewing tasks. Interestingly, our findings indicated that perceived speed of work (i.e. fast working) was another independent factor that was positively associated with the occurrence of MSP in all studied body regions (i.e. neck, shoulder and low back areas) among sewing workers. This finding may be attributed to the fact that these workers were paid based on the number of items they completed and this provided an incentive to work at high speed without adequate rest breaks. Moreover, the finding indicated that years of employment as a sewing worker was positively associated with the presence of symptoms in the neck and low back areas, which is in agreement with several previous observations (Kaergaard and Andersen 2000; Wang et al. 2007; Dianat and Salimi 2014). It is also interesting to note that the sewing workers in this study had frequent periods of long duration of sewing work without breaks (i.e. sitting in one place in a static or non-moving position for more than 2 hours), but this was only associated with the occurrence of neck complaints. The results from some previous studies suggest that the long duration of sitting work without a break may increase the risk for neck/shoulder pain among different occupational groups (Wang et al. 2007; Johnston et al. 2008; Dianat and Salimi 2014), and that regular rest breaks may reduce the risk for such complaints (McLean et al. 2001). Therefore, sewing workers should be advised to take regular rest breaks in order to minimise exposure and to help recovery from static and awkward postures.

The present study has an advantage that the observer error was controlled by using two trained interviewers in comparison to studies in which there were separate observer for each case. However, the findings presented should be interpreted in the context of the cross-sectional study design. In addition, the findings highlight the importance of both individual and work-related aspects of sewing tasks in association with MSP. Thus, in addition to the work-related factors, it might be useful to consider individual factors (such as age, gender and education) as potential confounders in future analysis of MSP among this working group.

Conclusions

In conclusion, the main finding of the study was that neck, shoulder and low back pain are frequent in workers involved in different sewing activities. The findings highlight the importance of both individual and work-related (psychosocial and physical) aspects of sewing tasks in association with MSP and emphasis the need for ergonomic interventions for improving the working conditions of this working group. Working posture and fast working were found to be as important predictors of MSP in all studied body regions. Number of years worked as a sewing worker was also shown to increase the risk for neck and low back pain among sewing workers. However, long duration of continuous sitting work without a break was only associated with the occurrence of neck pain. Based on the findings of this study, it is recommended that working postures of sewing workers should be improved through workstation design for sewing tasks (i.e. based on workers’ anthropometry). Moreover, workers involved in these tasks should also be advised to take regular rest breaks in order to alleviate exposure and also to aid recovery from unhealthy working postures. These findings highlight the role of prevention in the workplace in order to reduce MSP.