"This study assesses the causes of medical surveillance changes leading to specialist referral from one isocyanate-using company where 39 workers (about 20% of all employees) were referred to a hospital occupational clinic during a 5-year period for concerns regarding their surveillance respiratory questionnaire or spirometry results. The respiratory assessment determined that the questionnaire had detected 5 workers with non-occupational asthma, 2 with possible occupational asthma (OA), and 1 with subsequently confirmed OA, while no additional asthmatics were detected by spirometry without questionnaire findings. The surveillance questionnaire in this study was sensitive but not specific (no additional compensation claims for OA were made during this time period): workplace spirometry, however, did not add to the detection rate of asthma."

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