Individual and work related risk factors for neck pain among office workers
From: European Spine Journal. 2007 May; 16(5): 679–686.
Work related neck disorders are common problems in office workers, especially among those who are intensive computer users. It is generally agreed that the etiology of work related neck disorders is multidimensional which is associated with, and influenced by, a complex array of individual, physical and psychosocial factors.
The results of this study indicate that physical and psychosocial work factors, as well as individual variables, are associated with the frequency of neck pain. These association patterns suggest also opportunities for intervention strategies in order to stimulate an ergonomic work place setting and increase a positive psychosocial work environment.
Work related neck disorders are common problems in office workers, especially among those who are intensive computer users The worldwide trend is for people to use computers for longer periods daily, due to increased computer-based tasks at work as well as during leisure activities. Introduction of the computer into the workplace has meant changes in work organization, and a different use of worker physical and mental potential. It is generally agreed that the etiology of work related neck disorders is multidimensional which is associated with, and influenced by, a complex array of individual, physical and psychosocial factors. Among these various risk factors, work-related psychosocial factors appear to play a major role. Work-related psychosocial variables may include aspects of the work content, organization, and interpersonal relationships at work, finances and economics. Individual factors are considered as confounding factors that influence the relation between psychosocial demands and the occurrence of neck pain. Furthermore, psychosocial demands may be highly correlated with physical demands, which also indicate a confounding effect of physical factors on the relation between work-related psychosocial variables and the occurrence of neck pain.
The outcome was self-reported neck pain during the preceding 12 months. Neck pain was defined as pain in the head and neck region, shaded in a drawing of the head, neck and shoulder area.
Individual factors: the following individual characteristics were considered to be potential confounders: gender, age, height and weight from which body mass index was subsequently calculated, marital status, formal education, smoking, sleeping hours and leisure time (sport and hobby).
Work related physical factors: were assessed by questions about the duration of employment (years at current job, hours a week, days a week); physical tiredness at the end of the day; physical workload (postures, movements and forces related to the neck region) (nine questions); computer use; breaks during work (five questions); and climatological conditions (noise, lack of fresh air, dry air, changes of temperature, stench);
Work related psychosocial factors: mental tiredness at the end of the day; job pressure (seven questions); work variation (seven questions) and job satisfaction (11 questions) aiming at evaluating demands, control and autonomy at work, work organization and social support.
As in most studies, significant relationships were found between self-reported risk factors and the occurrence of neck pain. The cross-sectional design of this study however does not permit causal inference from the observed associations.
Individual factors. The prevalence of neck pain was substantially higher among women (18%) than among men (11%), which is consistent with previous studies. This gender pattern is seen in most types of body pain and several sociological, cultural and physical differences have been proposed as explanations, but these hypotheses have not been shown to be satisfactory. Smaller stature and lower strength of the shoulder muscles have been suggested to partly explain the sex difference. Concerning computer work in particular, gender differences have been found, for example, in the use of a computer mouse. Women are working with higher relative musculoskeletal load, for instance, applying higher forces to the mouse and using greater rang of motion, than are men. Additionally, women are known to report more symptoms than men.
A reversed U-shaped association was found between age and the prevalence of neck pain. The risk of neck pain increased until the age of 50 and decreased slightly thereafter. This is in line with earlier studies. The increase with age can be understood by increasing degeneration of the cervical spine with age. The decrease of neck pain in the oldest age group is more difficult to explain. One explanation could be that chronic diseases and other ailments may gain the upper hand.
Being physically active decreases the likelihood of having neck pain. Korhonen et al. found in their cohort study that employees who exercised less frequently demonstrated a higher risk of neck pain. This may have some clinical implications: as concluded by Hildebrandt et al., stimulation of leisure time physical activity may constitute one of the means of reducing musculoskeletal morbidity in the working population, in particular in sedentary workers.
Work related physical factors. Often holding the neck in a forward bent posture for a prolonged time, and often working in the same position for a prolonged time were significantly associated with neck pain. Ariens et al. found a trend for a positive relation between neck flexion and neck pain, although not significant, suggesting an increased risk of neck pain for those who spent a high percentage of the working time with the neck at a minimum of 20° of flexion.
Often making the same movements per minute was significantly associated with neck pain. When performing work with the hands and fingers, the muscles in the neck/shoulder region must usually act as stabilizers. Static contraction of the trapezius and other shoulder muscles is needed to keep the arms at right angles, a necessary posture when using the keyboard. This contraction is accentuated when there is also rotation or bending of the neck when the computer screen is placed to the side of the worker, not in front which is the recommended position. However, Szeto et al. attributed changing muscle patterns to reflect more the subjects’ personal habitual movements and postures rather than the influence of their workstations.
A significant positive relation was found between sitting posture and neck pain. The results of the present study confirm previous findings. Ariëns et al. found that workers who sat for more than 95% of the working time the risk of neck pain was twice as high as for worker who hardly ever worked in a sitting position. Skov et al. found that the odds ratios for neck pain increased with the time spent working in a sitting position, suggesting a clear relation between sitting posture and neck pain. Kamwendo et al. reported an odds ratio of 1.49 for the relation between sitting for more than 5 hours a day and self reported neck pain. According to Ortiz-Hernandez et al., remaining seated for long periods, usually accompanied by curvature of the spine, increases pressure on vertebral discs, ligaments, and muscles.
Some climatological conditions (dry air and temperature fluctuation) seem to be a significant predictor in our data. This is in agreement with the study of Korhonen et al. who found a positive association between the different aspects of physical work environment and neck pain. Rocha et al. demonstrated that inadequate thermal comfort was associated with neck symptoms. The variables of the climatological conditions were self reported. There is a possibility of bias as subjects with neck pain may have a different perception of their work environment.
Analyses of the association between neck pain and work related physical factors, revealed that neck pain was significantly associated with computer working time. Previous results are inconsistent about this association. One should take into account that the time used for computer work was measured as self reported proportion of total working time, which may result in overestimation of the time spend on the computer.
Work related psychosocial factors. Different work related psychosocial factors showed a positive association with neck pain, but only mental tiredness at the end of the day and shortage of personnel were independently related. Reporting shortage of personnel may be an indirect reflection of work (over) load. There is consistent evidence that stress is associated with neck pain in both cross sectional and longitudinal studies.
The protective effect of rest breaks observed in this study was also reported in other studies. Breaks allow a reduction in computer exposure, but more especially permit muscle relaxation.
The study results suggest that effective intervention strategies aiming at reducing the occurrence of neck pain most likely have to take into account both ergonomic improvements and cognitive behavioural aspects. Based on the results of this study, intervention should be applied to reduce computer exposure and also toward improving ergonomic conditions. Dynamic and sit/stand chairs will lead to more variation in posture and comfort. The use of document holders, a correct placement of the screen and adjustable chairs will reduce the neck load. Compulsory rest breaks could be introduced to reduce computer use.
However, to date, the preventive effectiveness of neck schools, based predominantly upon ergonomic principles, is not convincing. Therefore, future research should focus on evaluation programs for workplace prevention strategies aimed at reducing both mechanical and psychosocial risk factors.
