Study design
This post-hoc study pooled the eighty severe preschool children (1-5 years old) with analysable bronchial biopsies from the “P’tit Asthme” and the “RESPIRE” studies (N° NCT02806466 and NCT04558671 atClinicalTrials.gov ) (14). The design, inclusion criteria, and procedures for these studies have been previously described (14). Briefly, for all patients, clinical (sex, age, body mass index, birth history, personal history (age at first episode of wheezing, birth weight and gestational age), tobacco exposure, atopic dermatitis, allergic sensitization, gastroesophageal reflux, parental history of atopy and treatment), biological (total blood immunoglobin E & eosinophils) and fibreoptic bronchoscopy parameters (BALF cytology, BALF microbiology (positive bacterial cultures and viral multiplex PCR identification), bronchial remodelling parameters (RBM-BSM distance, submucosal fibrosis area, mucus gland area, epithelial integrity, density of blood vessels, BSM area and RBM thickness) and density of inflammatory cells (neutrophils, eosinophils, lymphocytes, mast cells and macrophages) in bronchial biopsies were assessed. Patients were then followed-up for one year and the number of exacerbations (acute symptoms requiring oral corticosteroids burst), hospitalisations, emergency visits and treatments were collected (14). Patients were then divided into three groups according to the number of exacerbations in the year following fibreoptic bronchoscopy: “No-Ex” (no exacerbation), “Low-Ex” (one or two exacerbations) and “High-Ex” (three or more exacerbations).