Preschool Bronchial Remodeling and Risk of Exacerbation
Condition: Preschool Severe Asthma
MeSH terms: Asthma
Study type: Observational

Summary: 
      Bronchial remodeling is an abnormal tissue repair process of the bronchial wall components
      that characterizes severe asthma which can include epithelial abrasion, thickening of the
      reticular basement membrane (RBM), an increase in bronchial fibrosis, blood vessel count,
      mucosal gland mass and/or bronchial smooth muscle (BSM) mass. We identified using latent
      class analysis two classes of patients. Compared to the second class, the first class was
      characterized by an increase in RBM thickness, blood vessel count, BSM mass and a decrease in
      RBM-BSM distance, mucus gland mass and bronchial fibrosis. We then hypothesized that this
      first latent class identified children at risk of asthma exacerbations.
    

Detailed description: 
      Asthma is the most frequent chronic disease in children. Severe asthma is characterized by
      airway hyperresponsiveness, bronchial inflammation and bronchial remodeling 1. Bronchial
      remodeling is an abnormal tissue repair process of the bronchial wall components which can
      include epithelial abrasion, thickening of the reticular basement membrane (RBM), an increase
      in bronchial fibrosis, blood vessel count, mucosal gland mass and/or bronchial smooth muscle
      (BSM) mass. At preschool age (before 6 years old), asthmatic children constitute a
      heterogeneous population and several classifications have been proposed to identify distinct
      phenotypes according to the chronology of asthma 2, the triggers of asthma 3, the trajectory
      of lung function as measured by forced expiratory volume in 1 second (FEV1) 4 or according to
      a combination of clinical and inflammatory variables 5. More recently, we demonstrated for
      the first time using latent class analysis (LCA) that subgroups of severe asthmatic children
      could also be identified according to bronchial remodeling parameters (unpublished data).
      Indeed, we identified two latent classes of patients. Compared to the second class, the first
      latent class was characterized by an increase in RBM thickness, blood vessel count, BSM mass
      and a decrease in RBM-BSM distance, seromucosal gland mass and bronchial fibrosis
      (unpublished data). Since, previous studies showed that bronchial remodeling could have
      negative impact on the patients' outcomes, we therefore hypothesized that the latent classes
      identified from the bronchial remodeling data in severe preschool asthmatic children included
      in the "P'tit Asthme" study (NCT02806466) could identify children at risk of asthma
      exacerbations requiring systemic corticosteroids therapy.
    

Intervention name(s): asthma exacerbations
Intervention type(s): Other
Intervention description(s): to collect the number of asthma exacerbations between the 2 latent classes of patients within the year following bronchoscopy
Observational model: Cohort
Time perspective: Retrospective
Sampling method: Non-Probability Sample
Study population: 
        Severe preschool wheezers (1-5 years old) according to ERS and ATS modified criteria and
        requiring flexible bronchoscopy according to ERS guidelines.
      
Keywords: exacerbation; children; asthma; bronchial remodeling; wheezing