Clinico-biological Correlation of Severe Asthma in Children
Clinico-biological Correlation of Severe Asthma in Children
Asthma is the most common chronic respiratory disorder in children. Despite significant
 advances in understanding of asthma, available therapies fail to alter the natural history
 and progression of the disease. Airway epithelial cells are continuously exposed to and
 injured by environmental irritants, such as viruses and pollutants, and as such are ideally
 situated to orchestrate airway function in response to these stimuli.

 Severe or difficult-to-treat asthma in children is a complicated disorder characterized by
 ongoing symptoms and persistent airway inflammation and oxidant stress despite corticosteroid
 treatment. Although severe asthma is likely a heterogeneous disorder, affected children
 similar clinical features, including gas trapping, bronchial hyperresponsiveness, and
 aeroallergen sensitization. However, the molecular and cellular pattern of inflammation in
 children with severe asthma are not uniform : some investigators have found increased
 eosinophils and TH2 derived cytokines, others have noted noneosinophilic patterns with
 neutrophil activation.

 Given the heterogeneity of the inflammatory response in children with severe asthma,
 additional methods to distinguish severe asthma are needed.
Inclusion Criteria:

 -  Children 0-18 years

 -  patients followed regularly for at least one year.

 -  The diagnosis of asthma is increased according to the criteria of the Global
 Initiative for Asthma (GINA): children with a history of recurrent episodes of
 bronchial obstruction.

 -  children with severe asthma defined by the American Thoracic Society (ATS): Severe
 asthma is defined by the presence of a major criterion: the need for high doses of
 inhaled corticosteroids (budesonide dose equivalent 400 micro g) and least two of the
 five minor criteria:

 -  The daily use of beta 2 long-acting or short-term daily action (<4 years) or
 anti-leukotrienes associated with inhaled corticosteroids Daily or almost daily use of
 beta-2 short-acting Permanent-bronchial obstruction (FEV <80% predicted FEV)

 -  At least one emergency department visit for asthma exacerbations in France

 -  At least 3 courses of oral corticosteroids per year

 Exclusion Criteria:

 -  parents' refusal to participate in the study

 -  refusal children to participate pathology underlying cardiac, neuromuscular,
 immunodeficiency