Effectiveness of a medical surveillance program for the prevention of occupational asthma caused by platinum salts: a nested case-control study

Abstract

Background: Exposure reduction has proven to be effective in the prevention of occupational asthma. Few data are available on the effectiveness of secondary prevention programs, including medical examinations and removal of workers from exposure sources after detecting symptoms or signs indicative of a beginning disease.

Objective: We sought to assess the effectiveness of a medical surveillance program in workers with exposure to platinum salts.

Methods: A nested case-control study was performed in 14 workers of a catalyst production plant whose skin prick test (SPT) responses to platinum salt converted from negative to positive during a 5-year prospective cohort study with yearly medical examinations and 42 matched control subjects from the plant who did not experience SPT response conversion. With the exception of 2 subjects, the workers showing SPT response conversion were removed completely from exposure sources and followed for up to 42 months.

Results: Work-related new symptoms were reported by 9 of the 14 subjects, and new symptoms without relation to work were reported by 3 subjects at the time of SPT response conversion. Symptoms were not accompanied by a change in FEV(1) or bronchial responsiveness to histamine. Symptoms resolved after transferral, but occasional shortness of breath or wheeze persisted in 4 subjects. SPT reactions decreased or became negative in all workers after complete removal but remained unchanged in a craftsman with ongoing occasional exposure to contaminated materials.

Conclusion: Although no randomized intervention was performed, this study proves the effectiveness of a medical surveillance program for the prevention of occupational asthma caused by platinum salts.