Chest
Clinical InvestigationsOccupational Asthma due to Various Agents: Absence of Clinical and Functional Improvement at an Interval of Four or More Years after Cessation of Exposure
Section snippets
Subjects
In the first follow-up study,4 we surveyed 32 individuals exposed to various agents out of 45 consecutive subjects who satisfied the criteria of follow-up, ie, (1) diagnosis confirmed by specific inhalation challenges in the laboratory or by monitoring of peak expiratory flow rates and bronchial responsiveness (or by both); and (2) cessation of exposure for at least six months. Three subjects were still exposed, one subject sensitized to pollens was contacted during the pollen season and
Results
The mean age of subjects at the time of diagnosis was 46 years (range, 20 to 64 years). The mean durations of exposure before and after the onset of symptoms were 6.3 months (range, 1 to 39 months) and 3.2 months (range, <1 month to 12.5 months), respectively. Follow-up assessments were performed 2.3 years (range, 3 months to 5.7 years) and 5.8 years (range, 4.3 to 10.9 years) after subjects were removed from the workplace.
All subjects were still symptomatic at both follow-ups. Among the group,
Discussion
This study shows that even at a long-term follow-up (>4 years), the symptoms and bronchial hyperresponsiveness of most subjects with occupational asthma persisted. Only a minority of subjects no longer required bronchodilators. Most other studies, summarized in Table 4,1, 2, 3, 4, 5, 6, 7, 8 have also demonstrated a persistence of symptoms and bronchial hyperresponsiveness after subjects left the workplace; however, the percentage of subjects with persisting hyperresponsiveness is generally
ACKNOWLEDGMENTS
We thank Ms. Katherine Tallman for reviewing the manuscript.
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Occupational asthma in the cotton textile industry: Assessment by bronchial hyperreactivity and peak expiratory flow recording
2002, Revista Portuguesa de PneumologiaMechanisms of occupational asthma
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