Aims: To quantify the relative contribution of work related physical factors, psychosocial workplace factors, and individual factors and aspects of somatisation to the onset of neck/shoulder pain. Methods: Four year prospective cohort study of workers from industrial and service companies in Denmark. Participants were 3123 workers, previously enrolled in a cross sectional study, where objective measurement of physical workplace factors was used. Eligible participants were followed on three subsequent occasions with approximately one year intervals. Outcomes of interest were: new onset of neck/shoulder pain (symptom cases); and neck/shoulder pain with pressure tenderness in the muscles of the neck/shoulder region (clinical cases). Results: During follow up, 636 (14.1%) participants reported neck/shoulder pain of new onset; among these, 82 (1.7%) also had clinical signs of substantial muscle tenderness. High shoulder repetition was related to being a future symptom case, and a future clinical case. Repetition was strongly intercorrelated with other physical measures. High job demands were associated with future status as a symptom case, and as a clinical case. A high level of distress predicted subsequent neck/shoulder pain, and neck/shoulder pain with pressure tenderness. Conclusions: High levels of distress, and physical and psychosocial workplace factors are predictors of onset of pain in the neck and/or shoulders, particularly pain with pressure tenderness in the muscles. N eck/shoulder pain is frequently reported among workers with repetitive manual tasks as well as among some service workers. The aetiology is largely unknown, and most studies so far are cross sectional. 3 Prospective studies have been conducted, and physical and psychosocial workplace factors such as neck flexion, sitting, quantitative job demands, and coworker support have been found to be risk factors for neck pain in a recent study.4 Physical work with a heavy load, awkward postures, and mental stress were related to one-year incidence of shoulder pain. 5The multifactorial and multidimensional nature of musculoskeletal pain has been the subject of several studies, which have found that psychological distress and other somatic symptoms are related to unspecific pain complaints from the neck and upper extremity. We aimed to determine the contribution of: (a) physical workplace factors, (b) psychosocial workplace factors, and (c) individual factors and symptom reporting to the onset of new neck/shoulder pain and neck/shoulder pain with pressure tenderness. METHODSThe study was conducted as a four year prospective cohort study, with yearly assessment of exposures in the workplace and simultaneous questionnaire screening and clinical examinations; fig 1 illustrates the total flow in the study. RecruitmentThe study population comprised 3123 workers from industrial and service sector settings, enrolled in 1994 and 1995.

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Work-related physical and psychosocial factors, as well as several individual risk factors, are important in the understanding of neck/shoulder pain. The findings suggest that neck/shoulder pain has a multifactorial nature. Reduced health-related quality of life is associated with subjective pain and clinical signs from the neck and shoulders. The physical workplace factors were highly intercorrelated, and so the effect of individual physical exposures could only be disentangled to a minor degree.

Context Computer use is increasingly common among many working populations, and concern exists about possible adverse effects of computer use, such as carpal tunnel syndrome (CTS).Objectives To estimate the prevalence and incidence of possible CTS and to evaluate the contribution of use of mouse devices and keyboards to the risk of possible CTS.Design and Setting A 1-year follow-up study with questionnaires conducted in 2000 and 2001 at 3500 workplaces in Denmark, followed on each of the 2 occasions by a clinical interview on symptom distribution and frequency.Participants The questionnaire was sent to 9480 members of a trade union, with an initial response rate of 73% (n=6943), and 82% (n=5658) at follow-up. Main Outcome MeasuresAt baseline, there were 3 outcome measures: tingling/ numbness in the right hand once a week or more as reported in the questionnaire; tingling, numbness, and pain in the median nerve in the right hand confirmed by clinical interview; and tingling, numbness, and pain in the median nerve in the right hand at night confirmed by clinical interview. At 1 year of follow-up the main outcome of interest was onset of symptoms among participants who had no or minor symptoms at baseline. ResultsThe overall self-reported prevalence of tingling/numbness in the right hand at baseline was 10.9%. The interview confirmed that prevalence of tingling/ numbness in the median nerve was 4.8%, of which about one third, corresponding to a prevalence of 1.4%, experienced symptoms at night. Onset of new symptoms in the 1-year follow-up was 5.5%. In the cross-sectional comparisons and in the follow-up analyses, there was an association between use of a mouse device for more than 20 h/wk and risk of possible CTS but no statistically significant association with keyboard use. ConclusionsThe occurrence of possible CTS in the right hand was low. The study emphasizes that computer use does not pose a severe occupational hazard for developing symptoms of CTS.

Aims: To determine the occurrence of pain conditions and disorders in the forearm and to evaluate risk factors for forearm pain in a cohort of computer workers. Methods: A total of 6943 participants with a wide range of computer use and work tasks were studied. At baseline and at one year follow up participants completed a questionnaire. Participants with relevant forearm symptoms were offered a clinical examination. Symptom cases and clinical cases were defined on the basis of self reported pain score and palpation tenderness in the muscles of the forearm. Results: The seven days prevalence of moderate to severe forearm pain was 4.3%. Sixteen of 296 symptom cases met criteria for being a clinical forearm case, and 12 had signs of potential nerve entrapment. One year incidence of reported symptom cases was 1.3%; no subjects developed new signs of nerve entrapment. Increased risk of new forearm pain was associated with use of a mouse device for more than 30 hours per week, and with keyboard use more than 15 hours per week. High job demands and time pressure at baseline were risk factors for onset of forearm pain; women had a twofold increased risk of developing forearm pain. Self reported ergonomic workplace factors at baseline did not predict future forearm pain. Conclusion: 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.

It is unknown whether the relation between job strain and depression reflects causal characteristics of the working environment or reporting bias. The authors investigated reporting bias by analyzing individual versus work-unit measures of job strain and the risk of depressive symptoms (n = 287) and a diagnosis of depression (n = 97) among 4,291 employees within 378 work units in Aarhus, Denmark, 2007. All participants reported psychological demands and decision latitude, and the authors estimated mean values for each work unit. The odds ratios predicting depressive symptoms or a diagnosis of depression for the highest versus the lowest levels of individual, self-reported high psychological demands and low decision latitude were significantly increased above 2.5. When participants were classified by the work-unit mean levels, these associations were substantially smaller. For depressive symptoms, the odds ratios were 1.49 (95% confidence interval (CI): 0.88, 2.53) and 1.08 (95% CI: 0.84, 1.39), respectively, for psychological demands and decision latitude. For a diagnosis of depression, the odds ratios were 1.33 (95% CI: 0.57, 3.09) and 1.02 (95% CI: 0.68, 1.56), respectively, for psychological demands and decision latitude. These findings indicate that reporting bias inflates associations between job strain and the occurrence of depression, if studies rely on individual self-reports.

The results indicate that workers with repetitive tasks have increased risk of shoulder tendinitis, which partially can be attributed to force requirements.

NCT01214954.