Occupational exposures and airways disease : a study to develop and evaluate a questionnaire for eliciting occupational exposure history for community based studies

Abstract

The role of occupational exposures in the genesis of airways disease may be underestimated in workforce studies because of the "healthy" worker effect, due either to those with more resistant airways entering a workplace or those with work related airways disease changing or quitting their job. Both effects are minimised in population-based studies which have the disadvantage that occupational exposures are of necessity self-reported. The overall goal of this research was to develop and validate an instrument to measure occupational exposures in epidemiologic research in general population studies of airways disease.The study hypothesis was that self-reported exposure information pertinent to airway disease was as accurate a reflexion of exposure as information derived from industrial hygiene expertise. To examine the study hypothesis, use was made of occupational questionnaires completed by 338 adults participating in a Montreal community based study. A list of 927 reported jobs was submitted for coding of exposures to 2 industrial hygienists working independently to code exposures.Intra-subject reproducibility of questionnaire information, assessed using a test-retest approach in 33 subjects showed good overall concordance for most components of the work history. Inter-rater reliability (between hygienists) was also good for some categories of exposures.Validity analysis of self-reported exposure, using as a reference criterion the exposure coding by either hygienist lead to poor values for sensitivity and phi-coefficients but not for specificity. Slight improvement in sensitivities and phi-coefficients was found for latest job.While smoking, a family history and atopy were determinants of asthma in multivariate models, significant exposure response relationships were obtained only with self reported exposure, not with exposures coded by either hygienist. Nevertheless the coefficients and confidence intervals for self-reported exposures were, for most part, in the same direction and range as those for exposure coded by the 2 hygienists.These results are consistent with the study hypothesis that self reported exposures perform comparably, possibly even better than exposures based on industrial hygiene expertise in characterising exposure response relationships for airway disease in community based studies