Questionnaire surveys on health and working conditions: development of an instrument for risk assessment in companies.

Periodic Occupational Health Surveys (POHS) are frequently used by occupational health and safety services in the Netherlands as a risk assessment instrument. These surveys include a questionnaire on work and health. Systematic attention is paid in this questionnaire to a broad range of working conditions and health complaints. In this article a method is presented to identify and evaluate work risks and health problems in groups of workers. Working conditions and health in any given company or department are assessed by comparing questionnaire data from its worker populations with data from one or more reference populations. Significant differences are interpreted as signals for both adverse working conditions and health problems. Considerations and choices with regard to the technical, operational and strategic quality of the method are elucidated. Probabilities of alpha- and beta-errors, choice of significance levels, and selection of reference populations are dealt with. Finally, a way of presentation of the results is shown. The method is considered to be part of a broader approach toward risk assessment. We recommend the combined use of questionnaire results and other available information, such as workplace surveys and sickness absence data. Questionnaires about work and health can be seen as one step in a multi-phase design: like in many diagnostic processes, the latter phases can enhance the precision of previous results. Recommendations are made for validating and evaluating this instrument.