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

Abstract

<b>Rationale:</b> Although the noninvasive 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). <b>Aim:</b> To investigate whether the pattern of airway inflammation in IS is associated with distinct clinical phenotypes of OA. <b>Methods:</b> 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. <b>Results:</b> 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 (odd 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). <b>Conclusions:</b> 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.