Reference

BOHRF Original Authors' Main Conclusions

The original authors' main conclusions are taken from Abstract, Results and Discussion. They are decided upon by the authors of the BOHRF occupational asthma guidelines and form part of the guidelines.

Study hypothesized that persistence of asthma in subjects with occupational asthma after the end of exposure could be explained by presence of airway inflammation that can be documented even years after cessation of exposure. Study showed that lack of improvement in airway responsiveness in subjects with occupational asthma after removal from exposure is associated with the magnitude of functional impairment at the time of diagnosis, the time lapse since diagnosis, and presence of an inflammatory influx. Logistic regression showed that baseline PC20 and time lapse since diagnosis were significantly associated with PC20 values at follow up. In the latest follow up from the group, study showed that subjects removed from exposure for 5 years or more had a more favourable outcome than those seen at shorter interval. The current study extends those results to 10 years or more. Factors associated with a more favourable outcome were, as in the previous series, time lapse since diagnosis and PC20 value at time of diagnosis. The only differences is that the current work did not show significant differences in outcome according to the nature of the agent (high vs. low molecular weight), whereas author's previous work showed a tendency for subjects with occupational asthma due to low molecular weight agents to experience a more satisfactory outcome. Study concludes that failure to improve after cessation of exposure to an agent causing occupational asthma is associated with airway inflammation at follow-up.

BOHRF Associated Evidence Statements

The BOHRF occupational asthma guidelines state that this reference is associated with the following evidence statements