Assessment of Lifetime Occupational Exposure in an Epidemiologic Study of COPD

Ascertainment of lifetime occupational exposures in an epidemiological study of chronic obstructive pulmonary disease (COPD) is important in order to investigate its effect on the disease and develop prevention strategies. The aim of our paper is to describe and evaluate a methodology used to assign lifetime occupational exposure to participants in a case-control study of COPD where lifetime occupational history was ascertained through telephone questionnaire interviews. The methodology involved assigning to each individual a qualitative index of potential exposure to eight occupational hazards, summarized individually overall the job categories reported by the individual, and an overall qualitative index of lifetime exposure to all eight hazards. The eight occupational hazards scored were mineral dusts, metal dusts/fumes, organic dusts, irritant gases/vapors, sensitizers, organic solvents, diesel exhaust, and environmental tobacco smoke (ETS). Two industrial hygienists independently assigned the above indices based on: their expert opinion, a priori knowledge based on literature review, and study participants’ responses to interviewer questions regarding types and duration of exposure. To evaluate agreement of the assigned scores, we used the Kappa statistic to test the agreement between the two scorers on each of the indices. The Kappa statistic generally indicated good agreement between the industrial hygienists’ scores but varied by exposure from 0.42 to 0.86. Although the exposure scoring is somewhat subjective, it is based on experience of experts and review of the literature. This method, with subject interviews providing qualitative lifetime exposure data when air monitoring has not been conducted, is useful for reconstructing lifetime exposures.