title: Computer users' risk factors for developing shoulder, elbow and back symptoms.
abstract: OBJECTIVE
  This prospective study concentrated on determining factors of computer work that predict musculoskeletal symptoms in the shoulder, elbow, and low-back regions.
  
  
  METHODS
  A questionnaire on ergonomics, work pauses, work techniques, and psychosocial and work factors was delivered to 5033 office workers at baseline in early 1999 (response rate 69%) and to 3361 respondents at the time of the follow-up in late 2000 (response rate 77%). An increased frequency or intensity of symptoms was the outcome variable, including only nonsymptomatic respondents from the baseline questionnaire (symptom frequency below 8 days within the last 12 months or intensity score below 4 within the last 3 months).
  
  
  RESULTS
  In the follow-up, 10%, 18%, and 23% had symptoms more often in the elbow, shoulder, and low back, respectively, and 14%, 20%, and 22% had more intense symptoms. Women were more likely to be afflicted than men in all regions. In the full-fit multivariate logistic regression analysis, little influence on the timing of a rest pause and being disturbed by glare or reflection were significant predictors of shoulder symptoms, screen below eye height was a significant predictor for elbow symptoms, and previous symptoms was a significant predictor for symptoms in all regions. Computer worktime and psychosocial dimensions were not significant predictors.
  
  
  CONCLUSIONS
  Influence on work pauses, reduction of glare or reflection, and screen height are important factors in the design of future computer workstations. Since previous symptoms was a significant predictor of recurrent symptoms in all three regions under study, it can be concluded that musculoskeletal symptoms are persistent.
authors.affiliation: National Institute of Occupational Health, Copenhagen, Denmark. bjk@ami.dk
authors.forename: Birgit
authors.initials: B
authors.lastname: Juul-Kristensen
authors.forename: Karen
authors.initials: K
authors.lastname: Søgaard
authors.forename: Jesper
authors.initials: J
authors.lastname: Strøyer
authors.forename: Chris
authors.initials: C
authors.lastname: Jensen
mesh_terms: D000328:Adult; D001416:Back Pain / Q000209:etiology; D003201:Computers; D003718:Denmark / Q000453:epidemiology; D004550:Elbow; D006804:Ergonomics; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009140:Musculoskeletal Diseases / Q000209:etiology / Q000503:physiopathology*; D009784:Occupational Diseases / Q000209:etiology / Q000503:physiopathology*; D011187:Posture; D011446:Prospective Studies; D020069:Shoulder Pain / Q000209:etiology; D011795:Surveys and Questionnaires