Impact of Ongoing Treatment With Inhaled Corticosteroids During Specific Inhalation Challenges for Diagnosing Occupational Asthma

Specific inhalation challenge (SIC) tests are still the reference test for diagnosing sensitizer-induced occupational asthma (SIOA). The European Respiratory Society recommends the cessation of inhaled corticosteroids (ICS) 72 hours before SIC. To assess the effect of an ongoing ICS treatment during SIC on the maximum fall in forced expiratory volume in 1 second (FEV1), the change in methacholine provocative concentration of methacholine inducing a 20% fall in FEV1 (PC20), and sputum eosinophil counts after exposure to the suspected agent. We performed a retrospective analysis using a database of cases referred to our center for suspected SIOA from 1999 to 2022. The results of the SIC were compared between subjects treated with ICS during SIC and steroid-naïve subjects. Six hundred and seventy-one individuals underwent SIC in the laboratory. Three hundred and eighteen were treated with ICS, whereas 353 were steroid naïve. The proportion of subjects with a positive SIC was greater among ICS-treated subjects (39. 6%) compared with steroid-naïve subjects (27.5%, P < .001). A treatment with ICS did not influence the outcome of the SIC. There was no difference in the change in PC20 or the percentage of sputum eosinophils after SIC between steroid-treated and steroid-naïve subjects. An ongoing ICS treatment during an SIC did not affect the occurrence of an asthmatic reaction, the change in airway responsiveness, or eosinophilic inflammation after exposure to the suspected agent in subjects who have been treated with ICS for a long period of time.