Chronic non-specific lung disease and occupational exposures estimated by means of a job exposure matrix: The Zutphen Study

Information gathered in the Zutphen Study, the Dutch contribution to the Seven Countries Study that started in the 1960s, was used in this study. Of the 1266 men invited to take part in the 1985 survey, 939 (74%) participated. All participants were interviewed according to the BMRC chronic non-specific lung diseases (CNSLD) questionnaire and medically examined for CNSLD complaints by a trained physician. The physician also filled in a questionnaire containing questions concerning previous treatments for asthma, bronchitis and emphysema. Exposures were generated by means of a job exposure matrix on the basis of the longest performed job and the gain and grouped into 12 exposure categories. A logistic regression analysis was performed using the occupational exposures as the sector of industry dependent variables in allowing for smoking habits, age and socioeconomic status. For the diagnosis by the physician and treatment for emphysema and or bronchitis, the strongest elevated odds ratios were found, indicating an adverse effect of the occupational exposures. In contrast, the variable' ever treated for asthma' had odds ratios smaller than one with most of the exposure variables indicating a selection effect. In an analysis in which everyone who was ever treated for asthma was excluded an increase in the odds ratios compared with the first analysis was seen. The relationships between occupational exposures as generated by the job exposure matrix and CNSLD were stronger than those recently reported in the literature.