Association between upper extremity musculoskeletal disorders and mental health status in office workers

1 Introduction

Musculoskeletal disorders (MSDs) are one of the most common and costly problems related to work worldwide [1]. Work related MSDs are considered a major contributing factor in decreasing quality of life, absenteeism [1], occupational restrictions, loss of work time [2, 3], changing jobs and increasing job related injuries [4]. In Washington State, 37.5% of all the accepted work related Workers’ Compensation claims were upper extremity MSDs [5]. In a study in Bangladesh, upper limbs were among the most common regions affected by MSDs [1].

Sharan et al. [6] found shoulders (42.1%) to be the second most affected regions by MSDs among Indian information technology (IT) professionals. In another study, the prevalence of upper extremity MSDs among Iranian office workers ranged from 13.2 to 35.2%. These researchers recommended the need for more attention to MSDs among office workers [7].

It is widely accepted that MSDs in office workers are multifactorial and the risk factors are classified as a combination of individual, physical and psychosocial factors [8]. Previous studies reported that individual factors such as age, sex and educational level are associated with MSDs among office workers [7–12]. Office workers with prolonged static sitting postures only use a few specific muscles of their upper extremities. This physical condition makes them susceptible to upper extremity MSDs [13]. In this regard, sitting for more than four hours per day was found to be associated with MSDs among office workers [14]. Limited task variety and repetitive movements, inadequate rest breaks, fast work pace and poor ergonomic workstation were other physical factors which were related to MSDs [10].

Psychological risk factors are critical components of the multi-factorial nature of work related MSDs, especially in upper extremities [15, 16] and need to be evaluated in order to plan programs for successful preventing and monitoring MSDs in workplace as a strategic location in health promotion. There are several tools, which measure mental health status such as the General Health Questionnaire (GHQ-28). The GHQ-28 that is a screening tool to detect those at risk of developing psychiatric disorders assesses some common disorders such as somatic symptoms, anxiety/insomnia, depression and social dysfunction [27]. In a study among bank office workers, higher GHQ score was positively associated with the occurrence of MSDs during the previous week [16]. In Australia, comorbidity between musculoskeletal disorders and mental health problems was very high and the most common mental disorder was anxiety [18]. In another study, MSDs were often associated with depression and anxiety/insomnia [19]. In a study on the relationship between chronic back pain and mental health status, GHQ-28 screening test showed that somatic symptoms were the main cause of significantly poorer mental health among participants who self-reported back pain [20].

Although several studies have reported on MSDs and its risk factors including psychological factors among office workers, few studies have been conducted in Iran and almost none in Qom, a province in the central part of Iran, to date. On the other hand, the prevalence and risk factors of MSDs would vary considerably among people with the same occupation in different countries due to discrepancy in racial background, geographical location, ethnicity, socio-demographics [21] and culture [22, 23]. Therefore, it is justified to conduct a study in this Iranian province with a population of more than 66,700 office workers since there is no precise data available on their musculoskeletal health [24]. Thus, the aim of this study was to determine the prevalence of MSDs among office workers and its relationship with mental health status in Qom.

2 Method

This cross-sectional study, as part of a comprehensive study, was conducted during 2012-2013 Iran’s Qom province using a stratified random sampling. The aim of the comprehensive study was to investigate the physical and mental health of office workers. Our assumptions for calculation of sample size were followings:

α= 0.05, β= 0.01 (power = 90%), d = 5%, Esti-mated prevalence of upper extremity MSDs = 25% [25–28]. N = (Z(1-α/₂)+Z(1-β))²*P(1-P)/d²≠1498.

In this regard, a list of all public offices and their personnel was prepared. Among all office workers, 92% were men. Therefore, we considered two gender groups, based on the sex ratio, then we used a random number table to select samples. Finally, 1630 office workers (1500 men and 130 women) were selected for the study. Before the start of sampling, employers’ approvals were obtained. Details of the study were explained to the participants orally before the delivery of the questionnaires and the written informed consent was obtained. The study was approved by the ethics committee at Qom University of Medical Sciences (TUMS) and the researchers carefully managed the confidentiality of all information.

Coded questionnaires were delivered to participants and collected in person and included the Standardized Nordic Musculoskeletal Questionnaire and the General Health Questionnaire (GHQ-28) [17, 29]. In this study, the Nordic questionnaire was used to determine musculoskeletal pain in shoulders, elbows and hands/wrists during the past 12 months. The GHQ-28 developed by Goldberg in 1979 is a screening tool to detect those likely to have or to be at risk of psychiatric disorders. GHQ-28 assesses mental health status in four subscales consistingof somatic symptoms, anxiety/insomnia, severe depression and social dysfunction. A score of 23 or more in the GHQ-28 questionnaire and a score of six or more in its sub-scales were considered as a high risk of mental disorders [17]. The Persian version of the questionnaire was reported to be a valid and reliable tool by Nourbala et al. [30]. The validity and reliability of the Persian form of Nordic Musculoskeletal questionnaire were also reported [31]. The demographic data included sex, age, height, weight, the level of education (under diploma/diploma, academic education) and marital status (single, married). Body Mass Index was calculated by height/weight².

The Kolmogorov–Smirnov Test for goodness of fit for a normal distribution was performed. The participant’s t-test was used for comparison of means of continuous variables (age, years of work) between two groups. Categorical variables were presented in number (percentage), and the group comparisons were made using the Chi Square and Fisher’s exact tests. All calculations were performed using SPSS version 16 (SPSS Inc., Chicago, IL). Any p value less than 0.05 was considered as statistically significant.

3 Results

With a response rate of 91.3%, among all eligible office workers, 1488 participated in the study. In total, 1372 (92.2%) were men, 1303 (87.6%) were married, 1216 (81.7%) were right handed and 914 (61.4%) had BMI ≥25. The mean (SD) age and years of experience as an office worker were 36 (7.68) and 12.3 (7.5) respectively. The frequency of MSDs in various upper limb regions is shown in Fig. 1. The prevalence of MSDs during the last 12 months was 27.5%. That is, 410 office workers reported that they experienced MSDs in at least one area of their upper extremities; it means 412 workers reported that they suffered from MSDs in at least one part of their upper extremities. Shoulder symptoms were more prevalent than hands/wrists and elbows (18.1% compared to 13.9% and 5.3%, respectively). Table 1 shows the relationship between the participants’ demographic characteristics and the upper extremity symptoms. Symptoms of shoulders and hands/wrists were more prevalent among women (p = 0.01 and p < 0.001, respectively). Shoulder MSDs (Mean = 36.8, SD = 7.9, vs Mean = 35.7, SD = 7.6, t = 2.1, p = 0.04) and elbow MSDs (Mean = 38.0, SD = 7.5, vs Mean = 35.8, SD = 7.6 t = 2.4, p = 0.02) were associated with higher age. Years of work experiences was higher in participants who reported shoulder MSDs (Mean = 13.3, SD = 7.8, vs Mean = 12.1, SD = 7.5, t = 2.4, p = 0.02) and elbow MSDs. (Mean = 13.9, SD = 7.0 vs Mean = 12.2, SD = 7.6, t = 1.9, p = 0.04). Hand dominance was not associated with shoulder (χ²= 1.1, p = 0.6), elbow (χ²= 0.5, p = 0.8) and hand/wrist MSDs (χ²= 4.7, p = 0.1). Twenty-eight (1.9%) office workers reported three, 87 (5.8%) reported two and 295 (19.8%) reported one painful site of upper extremities. No association was found between age and years of experiences with the numbers of involved regions (p = 0.3 and p = 0.1, respectively) (Table 2). Factors such as the levels of education (χ²= 12.9, p = 0.3), marriage (χ²= 3.9, p = 0.2), and BMI ≥25 (χ²= 0.9, p = 0.8) were not related to the numbers of involved regions.

The assessment of mental health status showed 254 (17.1%) office workers were found to be at risk of developing a psychiatric disorder based on four subscales. That is, 190 (12.8%) suffered from somatic symptoms, 193 (13%) anxiety/insomnia, 103 (6.9%) social dysfunction and 237 (15.9%) severe depression.

The relationships between upper extremity pain and the number of painful sites with mental health status were assessed. The reported increasing numbers of painful areas of upper extremities were associated with increasing the total GHQ-28 scores and its subscales including somatic symptoms and anxiety/insomnia (Table 3). Total GHQ-28 and anxiety/ insomnia scores were significantly related to either shoulders, elbows, hands /wrists or total upper limb MSDs (Table 4). Office workers who reported MSDs symptoms (Mean = 3.8, SD = 2.7) had higher GHQ score compared to the participants with no MSDs symptoms (Mean = 2.3, SD = 1.6) (p < 0.001).

4 Discussion

The present study was conducted to the self-reported prevalence of upper extremity MSDs during a 12 month period and its association with mental health status. Based on the findings, the total prevalence of upper extremity MSDs was considerable (27.5%), including 18.1% shoulder, 13.9% hand/ wrist and 5.3% elbow symptoms. In other studies on office workers, the total prevalence of upper extremity symptoms ranged from 13% to 45%, with shoulders from 16% to 49.2%, elbows from 4% to 15.4% and hands/wrists from 10% to 35% [25–28]. This variance in the prevalence of MSDs found in the evidence literature can be explained by the differences of the population’s characteristics such as culture, inactivity, diet, gender, and age [32]. Another potential reason for the different prevalence of MSDs in several studies may be due to the wording of the questions in the questionnaire. There are a variety of definitions for terms such as: associated disabilities, severity and duration (day, week or month) of MSDs symptoms, prevalence of MSDs [33]. For example, some previous studies used a definition of pain lasting for 24 hours, one week, one month or during last 12 months [34, 35].

This study found that shoulders symptoms were more common in comparison with other parts of upper extremities including elbows and hands/wrists. This result supports the findings of the previous studies [7, 27]. Some explanations have been proposed for higher prevalence of upper extremity MSDs in shoulders. For example, other studies strongly suggest that static or sedentary position is a risk factor for musculoskeletal disorders of neck and shoulders [36]. In addition, limited rest breaks, motionless work postures for a long period of time and non-neutral postures of the shoulder increase MSDs in shoulders [37]. These characteristics represent the working pattern of many office workers with prolonged sitting position, poor body posture and using limited muscles [38]. In a review of the evidence literature regarding MSDs in computer work, different psychosocial factors such as time pressure, mental stress, job dissatisfaction, high workload and lack of social support from coworkers and superiors were introduced as risk factors for neck/shoulder MSDs. Nevertheless, the etiology of unspecific neck/shoulder and forearm MSDs is unknown [39].

In this study, most of the office workers that self-reported MSDs complained about pain in one specific body region and only about 7.7% reported pain in more than one body area during the past 12 months. Similarly, a study conducted to evaluate determinants of multi-site MSDs reported that approximately 4-5% participants had frequent pain in the past 12 months or disabling pain in the last month [40].

Approximately one in five office workers were at risk of developing a psychiatric disorder. Severe depression and anxiety/insomnia were the most prevalent mental health disorders, respectively and somatic symptoms and social dysfunction were less prevalent. In a study by Noorbala et al. [30] in Iranian adult population, depression and anxiety symptoms were more prevalent than somatic symptoms and social dysfunction.

In the present study, office workers, who self-reported either shoulder, elbow or hand/wrist pain, had higher scores in GHQ-28 (>23) than participants with no upper extremity MSDs. In other words, 26.8% of office workers with MSDs had higher scores in GHQ-28 compared with people with no MSDs reports, which indicates the need for more attention to their mental health. Furthermore, the office workers with more involved body regions had significantly higher scores in GHQ-28 (poorer mental health) than the participants with less involved regions. This was in accordance with the findings of another study [42]. In addition, Solidaki et al. [40] found that somatizing could be the main determinant of multi-site MSDs.

In line with our study, Akrouf et al. [15] reported that higher mental health score (based on GHQ-12) was a significant predictor of MSDs among bank office workers during the previous year. In another study among patients registered at one rural Primary Care Centre, patients with MSDs had higher scores in GHQ-28 and were more likely to be experiencing mental distress [24]. A further study by Nahit et al. [41] reported that high levels of psychological distress measured by the GHQ-28 were associated with shoulder pain.

In our study, two subscales of GHQ-28, including anxiety/insomnia and somatization, were strongly associated with upper extremity symptoms. However, social dysfunction was not correlated with the self-reported upper extremity symptoms. In the study of Parkes et al. [42], GHQ anxiety was the strongest predictor of upper extremity symptoms; i.e. the increase in GHQ anxiety score was related to the increase in MSDs complaints.

Several other studies suggested that psychological disorders such as anxiety could affect the occurrence of MSDs [43, 44]. Somatization tendency [45] and increased alertness of somatic symptoms [46] were also reported to be associated with MSDs.

There are several controversies about the relationship between depression, social functioning and MSDs complaints. In the study of Parkes et al. [42] depression was related to MSDs, but social dysfunction was not. Also, Choi et al. [47] showed a significant association between social functioning and upper extremity MSDs. Other studies revealed that depression was related to neck pain [43, 44]. Depressed people report their problems less than others, which makes the differentiation of musculoskeletal pain between the depressed and non-depressed more difficult. Therefore, it seems more studies are needed on the relationship between social functioning and depression, and musculoskeletal pain.

The MSDs were more prevalent among women. This is consistent with previous studies throughout the world [7, 48]. This gender differences could be described by several explanations such as physiological discrepancies (e.g., body dimensions and hormonal conditions) [49], different effects of risk factors on women and men [50], lower pain threshold in women [51] or lower pain reporting by men [52], and differences in occupational exposure at work [49] or at home [53]. Increasing age and years of work experience were associated with the development of shoulder and elbows’ symptoms in our study and other research [27, 54]. Increasing age may cause various systemic and degenerative changes in the structure and function of the human body. Musculoskeletal changes due to aging are attributed to changes in tendons, ligaments, muscles and joints tissues and to the limitations of the physical activities and the altered postures of the body. Office workers with longer years of experience were reported to have continuous physical stress on the joints over the years and longer duration of employment was significantly related to neck-upper extremity MSDs [55].

BMI index in the studied office workers was similar to the Iranian adult population [56]. In our survey, factors such as abnormal BMI, the level of education and marital status were not related to upper extremity symptoms. This was in accordance with the study of El-Bestar et al. [55]. In contrast, Choobineh et al. [27] showed that MSDs were more preva-lent among workers with abnormal BMI (ie, BMI <18.5 and BMI ≥25 kg/m2), the lower educated and married ones. Harris-Adamson et al. [57] also found that BMI ≥30 was associated with an increased risk of developing carpal tunnel syndrome (CTS) but the level of education was not. Some researchers suggest that the effect of BMI on different body organs is not the same. MSD symptoms are more prevalent in weight-bearing joints such as back and lower extremities than non-weight-bearing joints such as shoulder/neck and upper extremities due to increased forces across the joints. Hand dominance was not related to upper extremity MSDs too. It was in contrast to the results of Harris-Adamson et al. [57]. Therefore, evidence literature about the relationship between hand dominance, BMI, marital status and level of education with work related MSDs are insufficient and further studies will help to clarify their relationship. Indeed, differences in factors related to MSDs in several studies are due to some aspects of the individual differences, work content, years of experiences, physical and ergonomic situation in work place of office workers, the method of MSDs assessment, and method and sample size of the study [58, 59].

Conflict of interest

The authors have no conflict of interest to report.