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.

Detailed examination of self-reported exposures showed that mouse and keyboard time predicted elbow and wrist/hand pain from low exposure levels without a threshold effect, but mouse and keyboard time were not predictors of clinical conditions.

Background: Computer use may have an adverse effect on musculoskeletal outcomes. This study assessed the risk of neck and shoulder pain associated with objectively recorded professional computer use. Methods: A computer programme was used to collect data on mouse and keyboard usage and weekly reports of neck and shoulder pain among 2146 technical assistants. Questionnaires were also completed at baseline and at 12 months. The three outcome measures were: (1) acute pain (measured as weekly pain); (2) prolonged pain (no or minor pain in the neck and shoulder region over four consecutive weeks followed by three consecutive weeks with a high pain score); and (3) chronic pain (reported pain or discomfort lasting more than 30 days and ''quite a lot of trouble'' during the past 12 months). Results: Risk for acute neck pain and shoulder pain increased linearly by 4% and 10%, respectively, for each quartile increase in weekly mouse usage time. Mouse and keyboard usage time did not predict the onset of prolonged or chronic pain in the neck or shoulder. Women had higher risks for neck and shoulder pain. Number of keystrokes and mouse clicks, length of the average activity period, and micro-pauses did not influence reports of acute or prolonged pain. A few psychosocial factors predicted the risk of prolonged pain. Conclusions: Most computer workers have no or minor neck and shoulder pain, few experience prolonged pain, and even fewer, chronic neck and shoulder pain. Moreover, there seems to be no relationship between computer use and prolonged and chronic neck and shoulder pain.Musculoskeletal complaints have been regarded as an adverse effect of computer use, and numerous studies have been conducted, most of them pointing to an association between neck and upper extremity pain and duration of computer use. 1-6Most of these associations have been based on cross-sectional comparisons of self-reported computer, keyboard or mouse use and self-reported pain complaints. 7 A minority of studies which have used clinical outcome measures have either found too few cases with traditional medical diagnoses to perform meaningful analyses or have used diagnostics that were controversial.3 6 Recently, methodologies for assessing work activity during computer use have been evaluated, and activitybased recordings of computer use seem to be reliable and in agreement with measures obtained by observational techniques. [8][9][10][11] A recent review called for future studies to improve our understanding of safe levels of computer use by measuring the duration of computer use in a more objective way, differentiating between mouse and keyboard use.12 In a substudy of the NUDATA (Neck and Upper extremity Disorders Among Technical Assistants) study we found that even though self-reports of mouse and keyboard use were correlated with objective recordings, participants overestimated their mouse use two to three times, and their keyboard usage up to six times when compared with the recordings. 13 The aim of this study was to examine if obje...

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