Occupational Asthma

The importance of identification of occupational sensitizers when evaluating a patient with asthma is emphasized by the work of Malo and Ghezzo This important longitudinal observational study of 80 patients with confirmed occupational asthma investigated recovery of airway hyperresponsiveness after cessation of exposure using complex statistical modeling. The analysis showed that progressive improvement in airway responsiveness to histamine occurred after cessation of exposure. The most rapid improvement was seen in the first 2.5 years (0.27 natural logarithms of PC₂₀/year), but improvement or 0.09 natural logarithms of PC₂₀/year was evident for several years after this. In this study, in contrast to others, the duration of exposure, the type of occupational sensitizer, and the duration of symptoms before diagnosis did not relate to the rate of recovery in airway hyperresponsiveness.

Identification of occupational asthma is problematic. Girard and coworkers showed disappointing sensitivity (34.8%) and specificity (62.5%) of work and off-work PEF records in identifying occupational asthma in patients with a positive specific inhalation challenge, even when results were carefully scrutinized by five experts. The authors speculated that the poor validity of PEF monitoring in comparison to earlier studies might reflect the more widespread use of inhaled corticosteroids and long-acting ß₂ agonists by patients undergoing evaluation for occupational asthma. One potential solution is to incorporate induced sputum analysis because the addition of a significant work-related change in sputum eosinophil count improved the sensitivity of PEF monitoring. It also facilitated the potentially important observation that patients exposed to an irritant developed sputum neutrophilia. The clinical relevance of this observation needs to be investigated.

To determine the role of aerosols of endotoxin generated by working with mice, in causing respiratory symptoms in laboratory scientists and technicians, Pacheco and coworkers did a cross-sectional study in 269 workers at a research institution. Symptoms related to mice were recorded in 16% (34 of 212) of workers not sensitized to mice and in 46% (26 of 57) of workers sensitized to mice. Symptomatic workers were more likely to be atopic irrespective of whether or not they were sensitive to mice. Among workers not sensitized to mice, symptomatic workers spent more time performing animal experiments and had higher daily exposure to endotoxin than did asymptomatic workers. Among workers not sensitized to mice, daily exposure to endotoxin was the strongest predictor of symptoms (odds ratio, 30.8). The authors conclude that airborne endotoxin is associated with development of respiratory symptoms to mice in laboratory scientists and technicians who are not sensitized to mice.

The American Thoracic Society presents a statement from the first Jack Pepys Occupational Asthma Symposium.

Citations 1-5 of 5 total displayed.

An Effective Strategy for Diagnosing Occupational Asthma: Use of Induced Sputum

Frédéric Girard, Simone Chaboillez, André Cartier, Johanne Côté, Frederick E. Hargreave, Manon Labrecque, Jean-Luc Malo, Susan M. Tarlo, and Catherine Lemière
Am. J. Respir. Crit. Care Med. 170: 845 -850. First published online as doi:10.1164/rccm.200403-380OC [Abstract] [Full text]  

Recovery of Methacholine Responsiveness after End of Exposure in Occupational Asthma

Jean-Luc Malo and Heberto Ghezzo
Am. J. Respir. Crit. Care Med. 169: 1304 -1307. First published online as doi:10.1164/rccm.200312-1749OC [Abstract] [Full text]  

Guidelines for Assessing and Managing Asthma Risk at Work, School, and Recreation

Am. J. Respir. Crit. Care Med. 169: 873-881. [Full text]  

Airborne Endotoxin Predicts Symptoms in Non–Mouse-sensitized Technicians and Research Scientists Exposed to Laboratory Mice

Karin A. Pacheco, Charles McCammon, Andrew H. Liu, Peter S. Thorne, Marsha E. O'Neill, John Martyny, Lee S. Newman, Richard F. Hamman, and Cecile S. Rose
Am. J. Respir. Crit. Care Med. 167: 983-990. [Abstract] [Full text]  

Proceedings of the First Jack Pepys Occupational Asthma Symposium

Am. J. Respir. Crit. Care Med. 167: 450-471. [Full text]