A comparison of methods for the assessment of postural load and duration of computer use

Aim: 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.