Musculoskeletal symptoms of the upper extremities and the neck: A cross-sectional study on prevalence and symptom-predicting factors at visual display terminal (VDT) workstations
© Klussmann et al; licensee BioMed Central Ltd. 2008
Received: 05 October 2007
Accepted: 27 June 2008
Published: 27 June 2008
The aim of this study was to determine the prevalence and the predictors of musculoskeletal symptoms in the upper extremities and neck at visual display terminal (VDT) workstations.
In a cross-sectional study 1,065 employees working at VDT > 1 h/d completed a standardised questionnaire. Workstation conditions were documented in a standardised checklist, and a subgroup of 82 employees underwent a physical examination.
Using the Nordic Questionnaire, the 12-month prevalence of symptoms of the neck, shoulder region, hand/wrist, or elbow/lower arm was 55%, 38%, 21%, and 15% respectively. The duration of VDT work had a significant impact on the frequency of neck symptoms in employees performing such work > 6 h/d.
With regard to musculoskeletal symptoms of the upper extremities, preventive measures at VDT workstations should be focused on neck and shoulder symptoms (e.g. ergonomic measures, breaks to avoid sitting over long periods).
Selected international literature regarding symptoms or disorders in employees working at VDT workstations, in chronological order.
Amount of VDT work
Eltayeb et al. 2007  (Netherlands)
264 computer workers
not indicated (n.i.)
not indicated (n.i.)
- Prevalence of musculoskeletal complaints: neck: 33%, shoulder: 31%, upper arm: 12%, elbow: 6%, lower arm: 8%, wrist: 8%, hand: 11% (complaints during the previous year that lasted at least one week).
- Higher prevalence of musculoskeletal symptoms in women than in men.
Ye at al. 2007  (Japan)
2,327 VDT users
mean: 19.3 days/month
- Age less than 40 years, not receiving breaks during VDT work, and the presence of eyestrain and musculoskeletal pain were significantly associated with poor general health status (high GHQ scores).
- Using a VDT for more than 5 h/day was also marginally associated with high GHQ scores in women (p < 0.1).
- In conclusion, the management of physical health as well as work duration is important for good general health status among VDT users.
Thomsen et al. 2007  (Denmark)
18 cases (VDT-workers with symptoms); 20 controls (VDT-workers without symptoms)
cases: 47.0 h/week controls: 35.5 h/week
cases: 28.6 h/week controls: 23.9 h/week
- Computer users with forearm pain and moderate to severe palpation tenderness had diminished forearm extensor muscle fatigue response.
- Additional studies are necessary to determine whether this result reflects an adaptive response to exposure without any pathophysiological significance, or represents a part of a causal pathway leading to pain.
Kubo et al. 2006  (Japan)
2,161 office workers
- Positive relationship between VDT work and sick building syndrome (SBS) in men.
- Association between prevalence of SBS an duration of VDT work in women.
- Positive relationship between use of VDT and general symptoms, eye symptoms, respiratory symptoms, and skin rash.
- The authors suggested that extended hours of VDT use might be related to increased SBS symptoms. Moreover, psychosocial distress related to VDT work might mediate the relationship between VDT use and SBS symptoms in women.
Gerr et al. 2005  (USA)
intervention study (3 years)
3 intervetion groups
nA = 122
nB = 125
nC = 115
- No differences in risk of musculoskeletal symptoms were observed among participants randomly assigned to two workstation and postural interventions in comparison to participants who received no workstation or pos-tural intervention.
- The study provides no empirical basis for recommendation of one posture versus another for prevention of musculoskeletal symptoms among computer users.
Juul-Kristensen & Jensen 2005  (Denmark)
3,361 office workers in 11 Danish companies
- Working as much as 75% of the work time at the computer increased the probability of musculoskeletal disorders in the neck/shoulder and elbow/hand.
- The speed of work was a prognostic factor for symptoms in the lower back.
Lassen et al. 2004  (Denmark)
6,943 technical assistants and machine technicians with VDT
69.5% full time work
- Detailed examination of self-reported exposures showed that mouse and keyboard-related work time predicted elbow and wrist/hand pain from low exposure levels without a threshold effect.
- Mouse and keyboard-related work time were no predicting factors for clinical conditions.
Kryger et al. 2003  (Denmark)
same sample as in the study of Lassen et al. 
- Intensive use of a mouse device and (to a lesser extent) keyboard usage, were the main risk factors for forearm pain.
- The occurrence of clinical disorders was low, suggesting that computer use is not commonly associated with any severe occupational hazard to the forearm.
Sillanpää et al. 2003  (Finland)
office workers (n = 298), customer service workers (n = 238) and designers (n = 247)
total sample < 2 h/day: 2.3%; 2–4 h/day: 15.3%; 4–6 h/day: 23.0% > 6 h/day: 47.4%
- For all the occupations combined, the 12-month prevalence of musculoskeletal symptoms in the neck, shoulders, elbows, lower arms and wrists, and fingers were 63, 24, 18, 35 and 16%, respectively.
- The study indicated that musculoskeletal pain is common among computer workers in offices.
- There was no strong association between the duration of computer work and pain or between the duration of mouse use and pain, but workers' perception of their workstation as being ergonomically poor was strongly associated with an increased prevalence of pain.
- Authors advise that more consideration should be paid to the ergonomics of workstations, the placing of the mouse, the postures of the upper extremities and the handling of the mouse.
632 individuals with more than 15 h computer work per week.
mean 28 h/week
- Musculoskeletal symptoms (MSS) and disorders (MSD) in neck/shoulder (N/S) or hand/arm (H/A) were common among computer users.
- More than 50% of computer users reported MSS during the first year after starting a new job.
- The duration of keying (hours/week) was associated with H/A symptoms and disorders.
- The most common N/S MSD was somatic pain syndrome.
- Gender, age, ethnicity, and prior history of N/S pain were associated with N/S MSS and MSD. Gender, prior history of H/A pain, prior computer use, and children at home were associated with either H/A MSS or MSD.
- Authors suggested that the risk of musculoskeletal symptoms and musculoskeletal disorders may be reduced by encouraging specific seating postures.
Nakazawa et al. 2002  (Japan)
25,000 office workers
21% < 1 h/day 29% 1–3 h/day 22% 5–5 h/day 28% > 5 h/day
- Physical symptoms became more severe with increased daily VDT use without a threshold value effect.
- Mental and sleep-related disorders in workers using VDT for more than 5 h/day were significantly higher than in groups using VDT for > 1, 1–3, and 3–5 h/day.
- Duration of daily VDT use was linearly related to physical symptoms, and was non-linearly related to mental and sleep-related symptoms with a threshold effect of 5 h/day.
Ariens et al. 2001  (Netherlands)
1,334 workers from 34 companies
mean: 39.2 h/week
- Sitting at work for more than 95% of the working time seems to be a risk factor for neck pain.
- There tends to be a correlation between neck flexion and neck pain.
Bode & Isfort 2001  (Germany)
1,002 office workers (VDT ≥ 3 h/day)
mean: 5 h/day
24-month prevalence: induration of the neck and shoulder area: 62%, muscle pain in the arm: 24%, paresthesia in the arm: 16%, paresthesia in the fingers or pain in the hand: 13% and 12% respectively (multiple answers possible).
- Only 1/3 reported no symptoms.
Hartmann & Guetschow 1999  (Germany)
205 female office workers
- Monthly prevalence of symptoms: neck: 40%, shoulders: 36%
- Hand/arm disorders seemed not to be the main issue of VDT users.
Ertel et al. 1997  (Germany)
352 female office workers
mean: 8.4 h/day
mean: 5.45 h/day
- Prevalence of symptoms during and after work: shoulder & neck: 62.7%, back: 53.0%, head: 45.3% and hands/arms/legs: 24.2%.
Michaelis et al. 1997  (Germany)
1,720 office workers
- Point prevalence of musculoskeletal symptoms: 62%.
- Point prevalence of symptoms in the thoracic/lumbar spine in employees working at desk: 23% to 58% (increasing with age). Working at VDT increased prevalence by an average of 8%.
- Point prevalence of symptoms in the cervical region is 20% to 36% (increasing with age). The prevalence was significantly higher in employees working at VDT compared to employees working only at desks.
353 office workers
- No general differences between VDT and non-VDT users as to the occurrence of muscular problems.
- Combination of specific VDT work situations (e.g. typing work, work with a VDT for more than 20 h/week) and the presence of moderating factors was associated with excess risks of suffering from muscular problems.
Schwaninger et al. 1991  (Germany)
2,722 office workers in different companies
33% 1/4, 27% 2/4, 27% 3/4, 13% 4/4 of work time
- Prevalence of musculoskeletal symptoms: neck pain: 38%, back pain: 38%, pain in the shoulders: 32%, pain in the arms/hands: 11% (no indication of reference period).
- Only 1/3 reported no symptoms.
- The authors recommended an optimal ergonomic configuration of the work place, multifaceted tasks and regular breaks at the VDT workstation.
Aim of this study
The aim of this study was to determine the prevalence of work-related symptoms of the upper extremities and neck in employees who regularly perform VDT work. The cross sectional study focussed on workstations representative of German conditions with regard to VDT workstations' ergonomics and tasks to be performed by the employees. By means of standardised questionnaires, working conditions and employees' symptoms were assessed in order to describe approaches for preventive measures.
A short checklist was used to evaluate the VDT workstations, a standardised questionnaire for the employees' survey, and a standardised medical diagnostic tool was designed for the physical examination.
The checklist was based on a German VDT questionnaire (BiFra), which has been used since 1995 to evaluate various VDT workstations throughout Germany [30, 31]), and is also available in French and English . The respective reference database currently offers information on n = 18,620 VDT workstations . Data on the set-up of the VDT workstations in the present study were compared with the BiFra database in order to check the representativeness of the sample.
The checklist used in this survey contains 37 items regarding display (e.g. size, reflections; 7 items), keyboard/mouse (e.g. area in front of the keyboard or for mouse-movement; 6 items), desk and arrangement of the VDT and accessories (e.g. adjustability of height, space for legs; 7 items), chair (e.g. adjustability of height; possibility of changing working postures; 9 items), ambient and environmental conditions (e.g. lighting of office and desk; 8 items). The items are dichotomous (attribute is fulfilled or not) and were completed by five ergonomists trained before the study.
The employees' questionnaire was based on the Nordic Questionnaire , parts of the Copenhagen Psychosocial Questionnaire (COPSOQ ), and questions depicting work at the VDT. In this study, the respective German versions of these questionnaires were used [36, 37].
The questionnaire contained 112 items including sociodemographic factors (e.g. age, gender, years on the job, leisure time activities, smoking habits; 13 items), musculoskeletal symptoms (e.g. prevalence, disability; 58 items), questions about viewing (e.g. symptoms at the eyes, use of corrective lenses or glasses; 5 items), kind and extend of VDT work (e.g. daily proportion of typing, data entry, monitoring, job rotation; 8 items), general working conditions (e.g. time pressure, shift work, working posture; 15 items), psychosocial factors (e.g. job satisfaction, cognitive demands, influence of work; 23 items). Questions on musculoskeletal symptoms were mostly dichotomous, questions on VDT work tasks demanded the indication of percentage of the very task per day (e.g. typing) and were metric, questions about the amount of breaks during VDT work or job rotation were given with ordinal scales (from always to never). Ordinal scales were used in the questions about psychosocial factors as well. For further calculations, the items about psychosocial factors taken from the COPSOQ were transformed to metric scales (0 to 100) according to the instructions of the author .
Medical diagnostic tool
The medical diagnostic tool for the physical examination was added to analyse the extent to which symptoms could be attributed to specific tentative medical diagnoses using the SALTSA study's list of standard diagnoses of musculoskeletal disorders . The diagnostic tool consisted of a documentation and a reference sheet. The documentation sheet was separated into three parts. Part A was a general survey to document painful or symptomatic body regions. Part B dealt with specific examination techniques to be carried out if pain or symptoms in the specific regions were documented in part A. According to these results and with the help of a reference sheet, tentative diagnoses could be derived and assigned in a list of diagnoses in part C. The diagnostic tool including the reference sheet were developed following the procedure recommended in a SALTSA study .
Of the 82 employees who took the physical examination, only 81 could be identified by means of an individual coding on the questionnaire. One employee did not complete the questionnaire, but nevertheless underwent the examination.
Statistical methods employed
The aim of the survey was to determine various prevalences for musculoskeletal symptoms of the upper extremities, i.e. to get the percentage of subjects with symptoms in the relevant joints within a specific period. In addition, the 95% confidence interval (CI) was calculated. The calculation of a binomial confidence interval relies on approximating the binomial distribution with a normal distribution. According to Sachs , a binominal distribution is adequately approximated to normal distribution if n*p*q ≥ 9 (n = sample, p = frequency of outcome, q = 1-p).
The predictors of musculoskeletal symptoms were identified by means of logistic regression analysis and the calculation of odds ratios (OR)  using the SPSS® 12 statistical software, SPSS Inc. In all analyses alpha was set at p < 0.05 (two-tailed) .
The analysis was carried out separately in six steps for the individual regions:
1. Initial check of variables to detect possible collinearity and determination of the remaining confounder.
2. Determination of the correlation of the individual factors and symptoms.
3. Determination of the workplace factors, adjusted for individual significant factors.
4. Determination of the psychosocial factors, adjusted for individual significant factors.
5. Determination of the features of the workstation, adjusted for individual significant factors.
6. Development of a final model considering only the factors ascertained as significant in step 2–5.
Variables were defined as collinear if the correlation between them was r > 0.4. The variable with the highest correlation with the outcome variable "symptom in this region" was retained in the model; the other variable(s) were deleted. Before forming the final model, logistic regression analyses was carried out for all the categories adjusted to the significant individual factors. Only the remaining significant variables were included in the final model.
The study was performed in compliance with the Helsinki Declaration. The aims, methods, and procedures of the study were coordinated with and agreed by the management and the workers' council of the company.
Description of the employees' sample
Characteristics of the employees' sample: gender, age, and duration of daily VDT use at various workplaces (> 1 h/d)
Daily VDT work
Percentage of all
12-month symptom prevalence (bold font) with 95% confidence interval (95%-CI) and total number of affected employees classified according to age groups. (prev.=prevalence)
Symptoms of neck
Symptoms of shoulder
Symptoms of elbow/forearm
Symptoms of hand/wrist
Female, n = 379
Male, n = 678
All n = 1,057
1-week symptom prevalence (bold font) with 95% confidence interval (95%-Cl) and total number of affected employees classified according to age groups. (prev.=prevalence)
Symptoms of neck
Symptoms of shoulder
Symptoms of elbow/forearm
Symptoms of hand/wrist
Female, n = 379
Male, n = 678
All n = 1,057
Identification of symptom-predicting factors
Symptom-predicting factors were identified with the help of the six steps of multivariable analyses on the basis of the 12-month prevalence, as described above. Despite analysing separately for individual regions (neck, shoulder, elbow/forearm, hand/wrist), the results of these steps were described cohesively as some predictors are the same. First, the initial variables (Figure 2) were checked for collinearity (step 1).
Analysing the individual factors (step 2) revealed significant effects of gender on the neck (odds ratio (OR): 2.02, p < 0.001) and shoulder regions (OR: 1.83, p < 0.001), of years on the job on the shoulder region (OR: 1.02, p < 0.001) and elbow/forearm (OR: 1.02, p < 0.05), and of the Body Mass Index (BMI) on the elbow/forearm (OR: 1.05, p < 0.05). Sports and smoking habits had no significant effects on symptoms in any body region. Body height and weight were deleted as they correlated strongly with the BMI but the correlation between BMI and symptoms was higher. Also age was deleted as it correlated strongly with years on the job but the correlation between years on the job and symptoms was higher.
In step 3 (workplace factors adjusted to significant individual factors), typing (OR: 1.10, p < 0.01) and the frequency of job rotation (OR: 1.91, p < 0.001) showed a significant effect on neck symptoms, and working in laboratory compared to office workstations revealed a low significant effect on symptoms of the elbow/forearm (OR: 2.00, p < 0.05). Sitting was eliminated as it correlated strongly with typing but the correlation between typing and symptoms was higher. Brain work over long time periods and time pressure had no significant effects on symptoms in any body region.
Investigating the psychosocial factors (step 4, adjusted to significant individual factors) showed only one factor with significant effect (job satisfaction – symptoms of elbow/forearm: OR: 0.98, p < 0.01).
Quantitative demands, cognitive demands, influence at work, social support from colleagues and superiors, and social relationship in the company had no significant effects on symptoms in any body region.
In step 5 (features of the workstation adjusted to significant individual factors) adjustability of the chair showed a low significant effect on symptoms in the elbow/forearm (OR: 0.52, p < 0.05). Other factors (adjustability of desk, arrangement of monitor, keyboard and mouse or lighting of the office/workstation) had no significant effects on symptoms in any body region.
Multivariable analysis of symptom-predicting factors (12-month prevalence) – final model (step 6). The bold font indicates the significant factors.
Symptoms of neck
Symptoms of shoulder
Symptoms of elbow/forearm
Symptoms of hand/wrist
Years on the job
Body Mass Index
Chair optimally adjustable
Results of the physical examination
Characteristics of the subgroup who took the medical examination compared to the total sample
Daily VDT work (hours)
Working hours per week
Actual symptoms (%)
39.9 (± 9.5)
5.1 (± 2.3)
40.9 (± 6.8)
43.6 (± 8.4)
5.8 (± 2.2)
40.6 (± 6.0)
Aims of the study and review of methods
The basic aim of the study was to describe the period prevalence of musculoskeletal symptoms in the upper extremities among employees working at VDT workstations representative of German office workstations. In addition, factors predicting the occurrence of symptoms were to be identified. Both aims were achieved.
With the help of a standardised questionnaire and a checklist, the main features of VDT workstations were described, the employees were interviewed regarding their work and possible symptoms, and standardised physical examinations were carried out. The high degree of participation (95% of the subjects addressed) suggested that the employees were very interested in the topic and that the questionnaire was easily to complete. Whereas the high proportion of survey participants may be related to the frequent occurrence of musculoskeletal symptoms in VDT workers, the symptoms were apparently not severe enough to motivate the employees to seek medical advice. The checklist for evaluating the VDT workstations (based on BiFra [30, 31]), the employees' questionnaire (based on the Nordic Questionnaire  and the COPSOQ ), and the physical examination tool kit (based on the SALTSA Study ) were well suited for the study and can be recommended for further studies.
Representativeness of the working conditions
As with the 12-month symptom prevalence, the 1-week prevalence results revealed that the neck and shoulder symptoms were clearly more prevalent than the hand/wrist and elbow/forearm symptoms. With regard to the 12-month prevalence of the whole sample, the highest values were found in the neck (55%) and shoulder (38%) region. The least pronounced prevalence was found in the hand/wrist and elbow/forearm, with values of 21% and 15%, respectively. These results are similar to the findings of a study among computer office workers from the Netherlands using the Maastricht Upper Extremity Questionnaire (MUEQ). In this study, similarly to our findings, the most commonly reported complaints were neck and shoulder symptoms (33% and 31%, respectively), followed by upper arm complaints and hand (12% and 11%), and lower arm, wrist, and elbow complaints (8%, 8%, and 6%) . Comparing the figures, it is important to note that the MUEQ addressed symptoms only if they lasted at least one week during the previous year – thus being different from the Nordic Questionnaire. This fact might explain the considerable differences in the prevalence between the German and Dutch VDT-workers whereas the hierarchy of symptoms was the same in both studies. In a Finnish sample consisting of office workers, customer service workers, and designers, the 12-month prevalence of musculoskeletal symptoms were 63% in the neck, 24% in the shoulders, 18% in the elbows, 35% in the lower arms and wrists, and 16% in the fingers . This is a higher prevalence of neck symptoms and symptoms of the lower arms and wrists than in the present study. This might be explained by the higher proportion of women in the Finnish survey.
Shoulder, elbow/forearm, and hand/wrist symptoms are significantly more common in the BGS group than in the group of VDT workers (Figure 7). These differences are particularly substantial in women.
These findings should not be interpreted in a way that suggests that VDT work has a protective effect on symptoms of the shoulder, elbow/forearm, or hand/wrist. Instead, the authors suppose that the participants of the present study indicated less symptoms as they were thinking mainly on work-related symptoms (negative reporting bias).
Based on the generated data, multivariable analyses were conducted for the occurrence of symptoms in the various parts of the body, identifying an optimal set of variables explaining a maximum part of the variance in the presence of symptoms. As a result of this final analysis, only a few predictors could be identified for musculoskeletal symptoms of the upper extremities in the present study focussing on employees working at VDT workstations for more than 1 hour per day. Among the multitude of possible influencing factors investigated, only more than 20 years on the job, a high lack of job satisfaction, typing for at least 6 h/d, and limitations to take breaks significantly increased the 12-month prevalence of one or more musculoskeletal symptoms. In addition, women indicated symptoms in the neck and shoulders more frequently than men.
Most of the studies of work-related musculoskeletal symptoms or disorders reported a higher prevalence of risk in women than in men, regardless of the kind of work or occupation involved. The same difference exists between woman and men regarding VDT users [11, 17, 20, 21, 41–43]. For more details see the review by Wahlstroem .
Ekman et al. suggested that the higher prevalence of symptoms in women may be due to non work-related factors or that there could be a difference in the occupational exposure among men and women . In a review , possible reasons were summarised in the following four groups:
- differences in task type allocations or work tasks between men and women,
- higher physical stress or stress load of women from non-work activities such as childcare and household work,
- physiological differences, such as different body size or body mass or endocrine functions, and
- differences in the willingness to report or seek medical care for pain or discomfort.
Gerr et al. observed that women had higher values in reporting symptoms and were also at increased risk for disorders confirmed by physical examination . These findings confirm our observation that more women than men took the advantage of the physical examination. Yet in the present study the prevalence of disorders confirmed by physical examination did not differ significantly between men and women. To sum up, there seems to be evidence for women's increased risk of musculoskeletal disorders , but more research is needed on this topic.
Psychosocial factors have been discussed as predictors in many previous studies [4, 41, 46]. In a review, high job demands, low decision latitude, time pressure, mental stress, job dissatisfaction, high workload, and lack of social support from colleagues and superiors were suggested as risk factors for musculoskeletal disorders in computer workers .
In our model we used scales taken from the COPSOQ  to consider psychosocial factors concentrating on quantitative demands, cognitive demands, influence at work, social support from colleagues and superiors, social relationship in the company, and job satisfaction. Interestingly enough there was only a low but significant relationship between job satisfaction on the one hand and neck and hand/wrist symptoms on the other. Thus our findings correspond partly to the results of Ariens et al.  who described psychosocial factors as independent risk factors for neck pain.
With regard to work organisation, large amounts of typing and limited breaks during VDT work have been described as risk factors for musculoskeletal symptoms. In the present study "typing" more than 6 hours per day at a VDT workstation had a significant impact on the prevalence of neck symptoms. A similar exposure ("keying") was reported by Gerr et al. to be positively associated with hand/arm symptoms and disorders [20, 21]. In two Japanese studies, effects of the duration of daily VDT work on physical symptoms  or – in women – on the general health status  were documented. Bergqvist et al. described that combinations of specific VDT work situations (e.g. typing work, work with a VDT for more than 20 h/week) together with moderating factors were associated with an excess risk of suffering from muscular problems [27, 28]. The importance of the amount of VDT work was documented by Juul-Kristensen & Jensen  as well. These authors found that working as much as 75% of the working time at a computer increased the probability of musculoskeletal disorders in the neck/shoulder and elbow/hand.
However it seems to be questionable whether the VDT work as such or other aspects of computer work are related to the symptoms. According to Ariens et al. , sitting at work for more than 95% of the working time seems to be a risk factor for neck pain. In the present study sitting was strongly associated with typing and the amount of VDT work. Because of the close correlation between sitting, typing, and VDT work, there is no clear evidence as to which of these factors is the main predictor for neck (or other) musculoskeletal symptoms.
In the scientific literature there seems to be a consensus on poor ergonomic conditions at VDT workstations contributing to musculoskeletal symptoms or disorders [22, 43, 46]. As mentioned above, the majority of the workstations considered in this study were well or very well equipped. Due to this high ergonomic standard and the small variance found in our sample, the workstation characteristics had no effects on symptom prevalence in the multivariable analysis. A similar effect was reported by Michaelis et al. with respect to the possible impact of ergonomic factors on back pain .
In the sample investigated, some predictors could be identified for musculoskeletal symptoms of the upper extremities. Due to the stepwise procedure applied in the multivariable analyses, collinear factors could be excluded thus leading to rather slender models for the symptoms in the different regions. Yet it must be borne in mind that most of the ORs, and their lower confidence limits, are very close to unity and that the explained variance in the models was only small (Nagelkerke's R-square: 3–11%).
The figures of employees who voluntarily participated in the physical examination suggests that approximately 8% of the total sample could be addressed with intensive campaigning. The majority of the employees seeking medical advice seemed to do so because of acute or chronic pain.
The symptoms expressed by the employees could mostly be confirmed in the physical examination; tentative diagnoses were made for these cases. The diagnoses also revealed the great importance of symptoms in the shoulder and neck region as the most frequently diagnoses were cervicobrachial disorders, neck disorders, and the rotator cuff syndrome.
Significance of the results
Generally speaking, this study confirms the main findings of the literature [4, 11–29]. Neck and shoulder symptoms occurred significantly more often than symptoms in the distal parts of the upper extremities. Neck symptoms were associated positively with a large amount of typing per day. The data referring to prevalence, gender, age distribution, and duration of daily VDT work in the various studies can be considered comparable despite the fact that the questionnaires differ somewhat. For these reasons the results achieved here can be considered representative. The significant new findings of the current study are based on the simultaneous consideration of various regions of the upper extremities, various time periods (e.g. 1-week, 12-month prevalence), as well as the reporting of confidence intervals.
Limitations of this study
Information about workplaces and VDT workstations was obtained by ergonomists and can be considered objective. In contrast the information about musculoskeletal symptoms, psychosocial factors, and amount of daily VDT work was obtained by a survey of the employees thus being prone to over- or underestimation. The difference between self-reporting and observation of others in physical work was recently assessed to reach between 30–45% [47, 48].
The aim of this study was to determine the prevalence of symptoms of the upper extremities and neck and to describe possible predictors derived from working conditions. Information about non-occupational stress factors was not assessed, e.g. children at home, household work, ethnicity, or the history of symptoms described as predictors in literature . In addition, the factor work style was not assessed, i.e. the strategy that workers may employ for completing, responding to, or coping with job demands that might affect musculoskeletal health [49, 50].
The possible impact of these factors might account for the fact that the explained variance was only low (Nagelkerke's R-square: 3–11%) in the study presented.
Generally, the study is limited by the cross-sectional design, which is not suitable to assess the causal relationship between variables but only associations.
With regard to sample size and the high response rate (95%), a "healthy worker effect" among the employees addressed has to be considered. In addition, no information was available about the prevalence of musculoskeletal complaints in the small group of 277 employees absent on the assessment day. Sick leave due to musculoskeletal symptoms could be increased in this group. Both factors would lead to a minor underestimation of prevalence in the present study. Nevertheless, the overall response was high; therefore response bias seems to be unimportant.
The majority of the workstations fulfilled all criteria of the checklist with exception of those workstations that tended to be used irregularly and temporarily, i.e. workstations in the production or storage areas. Thus, the employees had rather good ergonomic conditions. Yet, the symptom prevalence at the VDT workstations investigated in the present study was impressive. The multivariable analyses showed that neck and hand/wrist symptoms occurred less frequently when VDT work was interrupted periodically and other tasks were performed. It is therefore recommendable that office employees vary their tasks regularly – even if the workstation guarantees a high ergonomic standard. In addition, physiotherapeutic measures can be employed to counteract the occurrence or aggravation of tissue injury. Furthermore, employee motivation and the involvement of employees in decision-making processes are measures that may increase job satisfaction and, in doing so, can have a positive impact on the physical as well as mental well-being of the employees.
With regard to musculoskeletal symptoms, preventive measures should focus on neck and shoulder disorders. As derived from this study, work organisation plays an important role, especially when ergonomic measures are largely implemented. The organisation of work should allow regular breaks of VDT work and avoid large amounts of continuous typing. The methods used in this study proved suitable to assess the workstation characteristics and the employees' symptoms thus helping to derive appropriate measures to avoid or moderate physical impairment. The data gathered in this survey can be used as a reference for further studies with comparable outcomes and in occupational safety and health campaigns addressing the ergonomic characteristics of VDT workstations. Occupational health services will be able to use the diagnostic tool kit for physical examination thus checking for tentative diagnoses which may be confirmed by a medical specialist and, if appropriate, via apparative diagnostics.
This study was funded by the German Federal Institute for Occupational Safety and Health (BAuA) with reference given to project number F1911. The authors thank Mrs. Eva Springob for performing the physical examination and Mr. Peter Dolfen, M.D., for giving access to the company and its employees. Mr. Thomas Ostermann, Ph.D., gave additional statistical advice and Mr. Peter Lenco gave advice with regard to the English language.
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