Occupational asthma: A practical approach

Although evaluation of possible occupational asthma may be complex, it can be pursued systematically by first assessing whether asthma is present, and then determining whether asthma is caused or triggered by the workplace or by alternative or confounding nonoccupational explanations. A detailed his tory is of great importance in raising suspicion of occupational asthma, bu t studies have shown that even detailed histories obtained by experienced s pecialists can lead to inaccurate conclusions about the presence or absence of occupational asthma. Consequently, objective measurements should be per formed to establish the diagnosis of occupational asthma whenever possible. If the patient is still working in the workplace, work-related changes in spirometry or peak flow measurements can confirm the diagnosis. For occupat ional asthma from some airborne sensitizers, immediate-type skin testing or in vitro tests for specific IgE may establish sensitization. However, ther e is evidence that for some isocyanates, in vitro tests for specific IgG se rum antibody levels correlate better with documented bronchospasm from isoc yanate exposure, even though the IgG antibody is not thought to be pathogen ic. Controlled, specific inhalation tests may be valuable, but they should be performed only, under experienced medical supervision. Intervention shou ld be focused on reducing or avoiding harmful workplace exposures so that p ermanent lung impairment and need for chronic medical treatment are avoided . Assessment of permanent impairment/disability from occupational asthma op timally, should be determined 2 years after the removal from occupational e xposure, when improvement has been shown to plateau and the patient will li kely have reached maximal medical improvement.