Self-reported working conditions of VDU operators and associations with musculoskeletal symptoms: a cross-sectional study focussing on gender differences

Abstract

The aim of the present study was to describe working conditions and the prevalence of musculoskeletal symptoms among male and female VDU operators, and to assess associations between work-related physical and psychosocial exposures and neck and upper limb symptoms by gender. The study population comprised a variety of occupations from both private and public sectors. Data on physical and psychosocial exposures were collected by questionnaires, as were data on musculoskeletal symptoms. Univariate associations between exposures and symptoms affecting the neck and upper limbs were estimated by calculating the prevalence ratios with 95% confidence intervals. We also assessed the potential excess odds ratio attributable to interaction between gender and, one by one, exposure variable. Women (n=785) used the computer on average 3.9 h/day and men (n=498) 3.6. Variation of different work tasks was lower among females than among males. Nineteen per cent of the women and 12% of the men did >3 h of continued computer work without breaks (>10 min) at least twice a week. Twice as many women as men experienced high job strain (high demands and low decision latitude). A higher proportion of women than men reported symptoms ⩾3 days the preceding month from the upper body, irrespective of body region. For many of the studied exposures the prevalence of symptoms in one or several body regions was increased with increasing exposure, indicating exposure-response relationships. Duration of computer work was associated with symptoms among both men and women. Only among men, duration of work with a non-keyboard computer input device was associated with symptoms. Only among women, job strain was associated with symptoms. Time pressure was associated with higher prevalence of symptoms among women. Among men, time pressure was associated with lower prevalence of symptoms. Thus, the associations differed between the genders. Women experienced higher prevalence of symptoms than men in all body regions and they were more often exposed to physical and psychosocial conditions that in previous studies have been considered harmful, than men.

Relevance to industry

Work-related exposures and the associations between these factors and musculoskeletal symptoms among VDU operators differed in some respect between men and women. This should be considered in intervention programs. The results from this study gives further support to the advice that duration of computer work, time pressure and job strain should be reduced in order to decrease the risk of muskuloskeletal disorders among professional computer workers.

Introduction

In recent years, the occurrence of work-related musculoskeletal disorders in the neck and upper limbs, such as finger extensor and flexor tendinitis, carpal tunnel syndrome and neck-shoulder myofascial pain, has increased dramatically and now account for nearly 70% of reported occupational illnesses in the USA (Bureau of Labour Statistics, 1996). Computer-intensive workplaces report a high prevalence and incidence of such disorders among the workers (Bergqvist et al., 1995; Faucette and Rempel, 1994; Punnett and Bergqvist, 1997; Tittiranonda et al., 1999). Among the working population in Sweden today, 68% of all men and 63% of all women use personal computers at work. Computerised work is likely to increase (SCB, 1999; Ekman et al., 2000). Of all reported work injuries due to musculoskeletal illness in Sweden, work with computer equipment was reported as the cause of the problems among 13% of the women and 4% of the men in 1998, compared with 6% and 1%, respectively, in 1992 (Wigaeus Tornqvist et al., 2001a).

Several epidemiological studies show that intensive computer work and factors related to work organisation, as well as physical and psychosocial exposures in computer work, are associated with increased risk of neck and upper extremity disorders (Tittiranonda et al., 1999; Ekman et al., 2000; Wigaeus Tornqvist et al., 2001a).

Studies of modern working conditions report substantial changes in work organisation and work content, concerning factors like downsizing, just-in-time jobs, time pressure, job demands and decision latitude (Aronsson, 1999; Härenstam et al., 2001). To a great extent this also concerns computerised modern work.

New technical devices are continuously being introduced to supplement the keyboard, such as the computer mouse, track-ball, computer pen, pointer, track-point, track-pad and even voice control. A good ergonomic design of the computer workstation is important to avoid musculoskeletal disorders (Sauter et al., 1991; Karlqvist, 1998; Aarås et al., 1999). The design is also important for comfort, productivity and quality of the VDU-produced work (Tittiranonda et al., 1999; Jensen et al., 2001).

Exposures relevant to the occurrence of musculoskeletal disorders include both physical workload and the organisation of work in general (Punnett and Herbert, 2000). There is scientific evidence of cause-and-effect relationships between repetitive motion, forceful work, and postural stress for disorders of the back and upper extremities (Bernard, 1997). The risk is particularly high when two or more of these job features are simultaneous and exert synergistic effects. Thus, primary prevention of musculoskeletal disorders in the workplace should include ergonomics programs that emphasize, e.g. the ergonomic design of workstations, equipment, tools, and work organisation to fit the capabilities and limitations of the human body (Hagberg et al., 1995; Westgaard and Winkel, 1997). Work organisation determines, e.g. work pace, repetitiveness, duration of exposures, and recovery time as well as psychosocial dimensions of the work environment such as decision latitude, psychosocial job demands, and social support from supervisors and among co-workers. High psychological work demands typically involve both rapid physical work pace and feelings of time pressure. Highly stereotyped finger motion patterns occur when a manual job both is monotonous and offers little decision autonomy (Punnett and Herbert, 2000).

Being a female is often described as a “risk factor” for many musculoskeletal disorders because prevalence in the general population and in large groups of employees have been reported to be twice as high among women compared to men (Viikari-Juntura et al., 1991; de Zwart et al., 1997). As Punnett and Herbert (2000) point out, depending of the gender segregated labour market it is essential to distinguish between gender differences in crude prevalence or risk and differences in the effects of occupational exposures on musculoskeletal outcome. The associations of musculoskeletal disorders with gender and occupational ergonomic exposures should be assessed separately in order to determine whether women are at increased risk when exposed to the same ergonomic stressors as men.

The aim of the present study was to describe working conditions and the prevalence of musculoskeletal symptoms among male and female VDU operators, and to assess associations between work-related physical and psychosocial exposures, respectively, and neck and upper limb symptoms, and whether these associations differed between women and men.