Prevalence of Arm, Neck and Shoulder Complaints Among Computer Office Work
Background: Complaints of Arm Neck and Shoulder (CANS) represent a wide range of complaints, which can differ in severity from mild, periodic symptoms to severe, chronic and debilitating conditions. They are thought to be associated with both physical and psychosocial risk factors. The measurement and identification of the various risk factors for these complaints is an important step towards recognizing (a) high risk subgroups that are relevant in profiling CANS; and (b) also for developing targeted and effective intervention plans for treatment. The purpose of the present study was to investigate the prevalence of CANS in a Dutch population of computer workers and to develop a questionnaire aimed at measuring workplace physical and psychosocial risk factors for the presence of these complaints.
Methods: To examine potential workplace risk factors for the presence of CANS, the Maastricht Upper Extremity Questionnaire (MUEQ), a structured questionnaire, was developed and tested among 264 computer office workers of a branch office of the national social security institution in the Netherlands. The MUEQ holds 95 items covering demographic characteristics, in addition to seven main domains assessing potential risk factors with regard to (1) work station, (2) posture during work, (3) quality of break time, (4) job demands, (5) job control, and (6) social support. The MUEQ further contained some additional questions about the quality of the work environment and the presence of complaints in the neck, shoulder, upper and lower arm, elbow, hand and wrist. The prevalence rates of CANS in the past year were computed. Further, we investigated the psychometric properties of the MUEQ (i.e. factor structure and reliability).
Results: The one-year prevalence rate of CANS indicated that 54% of the respondents reported at least one complaint in the arm, neck and/or shoulder. The highest prevalence rates were found for neck and shoulder symptoms (33% and 31% respectively), followed by hand and upper arm complaints (11% to 12%) and elbow, lower arm and wrist complaints (6% to 7%). The psychometric properties of the MUEQ were assessed using exploratory factor analysis which resulted in the identification of 12 factors. The calculation of internal consistency and cross validation provided evidence of reliability and lack of redundancy of items.
Conclusion: Neck and shoulder complaints are more frequently reported among Dutch computer workers than arm, elbow and hand complaints. The results further indicate that the MUEQ has satisfactory reliability and internal consistency when used to document CANS among computer workers in the Netherlands.

Complaints of arm, neck and shoulder (CANS) were recognized in the early seventies as an important cause of work disability. They were introduced as "occupational cramps" or "occupational myalgia" and suspected of being associated with numerous occupations and work activities. The rapid development of information technology has entailed changes in working life during the recent decades. It is estimated that more than half of the working population in Western societies currently use personal computers at work. Additionally, the relative time spent in front of the computer and the use of a computer mouse has increased rapidly over the years. It is likely that these developments may have contributed to the increasing burden of CANS.

The term CANS is introduced in the Netherlands and indicates "musculoskeletal complaints of arm, neck and/or shoulder not caused by acute trauma or by any systemic disease". CANS may cause severe and debilitating symptoms such as pain, numbness, and tingling. It may further result in reduced worker productivity, inability to perform job tasks and an increase in workers compensation costs. In the Netherlands alone the incidences of CANS vary between 20 and 40% a year. In the USA, the Bureau of Labour Statistics estimated that in 1996 64% of all new work-related disability cases were related to CANS. Research efforts on the identification of risk factors for the development of work-related CANS, has shown that these complaints may not be caused solely by high physical job demands (such as repetitive movements, awkward posture etc.) but also by psychosocial demands (such as low social support, high job demands etc.). At the current stage, the exact relationship between these risk factors and the development CANS is still not clear and more research is needed.

The identification of risk factors for the development of CANS before they develop into a disabling musculoskeletal complaints is an important step in order to recognize relevant subgroups who have a high risk profile for CANS and also, in the longer run, to develop targeted and effective screening and interventions. Hence, targeting computer workers as the selected case population on which to base and to develop measurement tools specifying the risk factors of CANS would seem the appropriate first step.

Although there is an impressive body of literature with regard to measurement tools, nevertheless there is a need for developing a non complicated yet comprehensive questionnaire for the assessment of CANS. We selected several items related to the presence of CANS from the Karasek Job Content Questionnaire (JCQ) which had been used already in other studies on risk factors for upper extremity complaints. Additional, items were selected from the standardized Dutch Musculoskeletal Questionnaire (DMQ). The current study aims to present a questionnaire that would address the occurrence, nature and possible work-related physical and psychological risk factors of CANS among computer users with known psychometric properties. For this purpose a population of Dutch office workers was chosen. This paper presents the one-year prevalence rates of CANS in this working population and the psychometric properties (i.e. factor structure and reliability) of this questionnaire.