title: A comparison of methods for the assessment of postural load and duration of computer use.
abstract: OBJECTIVE
  To compare two different methods for assessment of postural load and duration of computer use in office workers.
  
  
  METHODS
  The study population existed of 87 computer workers. Questionnaire data about exposure were compared with exposures measured by a standardised or objective method. Measuring true exposure to postural load consisted of an observation of the workstation design and posture by a trained observer. A software program was used to record individual computer use.
  
  
  RESULTS
  Comparing the answers for each item of postural load, six of eleven items showed low agreement (kappa <0.20). For six items the sensitivity was below 50%, while for eight items the specificity was 80% or higher. Computer workers were unable to identify risk factors in their workplace and work posture. On average, computer workers overestimated their total computer use by 1.6 hours. The agreement among employees who reported a maximum of three hours of computer use per day was higher than the agreement among employees with a high duration of computer use.
  
  
  CONCLUSIONS
  Self-report by means of this questionnaire is not a very reliable method to measure postural load and duration of computer use. This study emphasises that the challenge to develop quick and inexpensive techniques for assessing exposure to postural load and duration of computer use is still open.
authors.affiliation: TNO Work and Employment, Polarisavenue 151, PO Box 718, 2130 AS Hoofddorp, Netherlands. j.heinrich@arbeid.tno.nl
authors.forename: J
authors.initials: J
authors.lastname: Heinrich
authors.forename: B M
authors.initials: BM
authors.lastname: Blatter
authors.forename: P M
authors.initials: PM
authors.lastname: Bongers
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D016288:Computer Terminals; D003201:Computers / Q000706:statistics & numerical data*; D030881:Disclosure; D005260:Female; D006801:Humans; D008297:Male; D009140:Musculoskeletal Diseases / Q000517:prevention & control; D009784:Occupational Diseases / Q000517:prevention & control; D016273:Occupational Exposure; D016272:Occupational Health; D011187:Posture; D015203:Reproducibility of Results; D012307:Risk Factors; D011795:Surveys and Questionnaires; D013647:Task Performance and Analysis; D013997:Time Factors; D016526:Workload