Phenotypes of occupational asthma defined with induced sputum after specific inhalation challenge

Rationale. - Although the non-invasive assessment of airway inflammation through the induced sputum (IS) technique identified distinct asthma phenotypes, there is few information on the determinants of airway inflammatory pattern in sensitizer-induced occupational asthma (OA). Aim. - To investigate whether the pattern of airway inflammation in IS is associated with distinct clinical phenotypes of OA. Methods. - This retrospective multicentric study was conducted among 372 patients with OA confirmed by a positive specific inhalation challenge (SIC) who were recruited in the European network for the Phenotyping of OCupational Asthma cohort (2006-2018). Each patient underwent an analysis of IS before and 24 hours after the SIC. Sputum eosinophilia and neutrophilia were defined by the presence of >= 3% eosinophils and >= 76% neutrophils in sputum samples collected after the SIC. Results. - In total, 268 (72%) and 42 patients (11%) exhibited sputum eosinophilia and neutrophilia, respectively. Multivariate logistic regression analysis revealed that eosinophilia was associated with exposure to a high molecular weight agent (odds ratio [OR], 1.89; 95% CI, 1.18-3.04), moderate asthma (OR, 3.17; 95% CI, 1,43-7.0) and severe asthma (OR, 2.39; 95% CI, 1.06-5.43). Sputum neutrophilia was associated with age (OR for each additional year, 1.04; 95% CI, 1.01-1.08), male gender (OR, 2.74; 95% CI, 1,21-6.8), mild asthma (OR, 3.26; 95% CI, 1.24-8.88), and dysphonia (OR, 2.83; 95% CI, 1.14-6.87). Conclusions. - Sputum eosinophilia post-SIC was predominant in OA patients. Sputum eosinophilia and neutrophilia were associated with distinct clinical phenotypes of OA, especially in terms of causal agents and asthma severity. (C) 2021 Elsevier Masson SAS. All rights reserved.