Published online: March 9, 2017
Allergic occupational asthma is a type of asthma caused by the exposure to agents with sensitizing properties at the workplace. The diagnosis of allergic occupational asthma is often difficult to establish. The reference test for diagnosing this condition, specific inhalation challenge (SIC), consists of exposing the workers to the suspected agent in a laboratory or at the workplace in order to induce a controlled asthmatic reaction. However, this test is only available in a few centers worldwide.
In a recent issue of The Journal of Allergy and Clinical Immunology: In Practice, Racine and colleagues evaluated the value of a combination of tests assessing airway inflammation (blood and sputum eosinophil counts) and airway responsiveness (methacholine inhalation challenge) for diagnosing occupational asthma in comparison to the reference test: SIC. Using a large database of 618 workers who underwent blood and sputum eosinophil counts as well as a methacholine inhalation challenge before and after SIC, they calculated the diagnostic accuracies of those tests performed before and after SIC for diagnosing occupational asthma.
Blood eosinophil counts were unable to differentiate workers with and without occupational asthma. In contrast, the combination of a methacholine inhalation challenge and sputum eosinophil counts before and after exposure to the suspected agent showed a good diagnostic accuracy for diagnosing occupational asthma compared to SIC as the reference test.
Performing a methacholine inhalation challenge and obtaining sputum eosinophil counts before and after a period at work could be an interesting alternative to the performance of SICs for diagnosing occupational asthma in centers that do have access to those tests.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.