Persistence of bronchial reactivity to occupational agents after removal from exposure and identification of associated factors.

OBJECTIVES: To examine the outcome of specific bronchial reactivity to occupational agents in patients with occupational asthma who have been removed from exposure to the offending agents and to identify risk factors for the persistence of specific bronchial reactivity.

DATA SOURCES: A PubMed (National Library of Medicine) search of articles published from January 1, 1985, through December 31, 2001, with the keywords occupational asthma and bronchial reactivity was performed.

STUDY SELECTION: This article represents a synthesis of these PubMed sources and the opinion of the author.

RESULTS: Specific bronchial reactivity persists in most cases even a long time after removal from exposure to the offending agents. This condition does not seem to be correlated with the persistence of bronchial reactivity to methacholine but seems to be related to the persisting level of specific IgE to the occupational agents in the case of high-molecular-weight agents and platinum salts.

CONCLUSIONS: Patients who have been diagnosed as having occupational asthma are at risk of developing an asthmatic reaction in the minutes following re-exposure to the offending agent, even if they no longer experience asthma symptoms, have normalized their bronchial reactivity, and have not been exposed to the offending agent for years. It is, therefore, crucial that these patients remain unexposed to the agent that caused their occupational asthma.