Asthma is a chronic respiratory disease affecting approximately 10% of the population, the majority of patients with very mild to mild asthma. Asthma is characterized primarily by the presence of symptoms clinical variables, reversible airway obstruction and airway hyperresponsiveness. Inflammation is a key factor in the pathophysiology of the disease. Eosinophilic inflammation is the most common type. However, in the literature it is usually associated with more severe and difficult to control asthma. Although mortality associated with asthma has drastically decreased in recent years, several events still occur. Strangely enough, these frequently affect mild asthmatics. Although there is still a misunderstanding in relation to these events, the most recent practice guides have recommended an approach based on the use of inhaled corticosteroids (ICS) in all, including mild asthmatics. This change of therapeutic cap is still debated, but indicates a need for new studies in this population. Recently, the investigators demonstrated that a subgroup of asthma patients with mild asthma had a eosinophilia. The evolution of this subgroup without bronchial obstruction or respiratory symptoms remains unknown. Indeed, it seems imperative to determine the fate of these subjects in comparison with asthma mild non-eosinophilic since it could be a subgroup at risk of poor outcome. The objective of this study will be to examine the course of asthma in very mild to mild asthma patients who exhibit eosinophilic inflammation of the respiratory tract compared to noneosinophilic subjects.

This will be a prospective observational, longitudinal study. Participants for whom a result of induced sputum showing an eosinophil level greater than or equal to 3% was observed at least 1 year ago will be contacted to participate in the study. They will be matched for age, gender and duration of asthma to subjects without eosinophilia. These subjects will not be on bronchial anti-inflammatory medication. They will have a complete evaluation including respiratory function tests, a methacholine challenge and sputum induction. They will also complete questionnaires on controlling their asthma and exacerbations.

Inclusion Criteria:

• With a proven diagnosis of asthma
• With very mild or mild asthma at the time of previous assessment
• With at least two sputum cell differential counts > 1 year before follow-up visit
• With stable asthma and asthma medication for at least 4 weeks before baseline assessment and before follow-up visit
• Able and willing to consent to study procedures

Exclusion Criteria:

• Conditions that could affect measurements, such as any active chronic or systemic inflammatory disease, not related to the respiratory system.
• Subjects with a main diagnosis of eosinophilic granulomatosis with polyangiitis (Churg- Strauss syndrome) or hypereosinophilic syndrome.
• Respiratory tract infection in the 4 weeks preceding past assessments and in the 4 weeks preceding follow-up visit.
• Asthma exacerbation in the 4 weeks preceding past assessments in the 4 weeks preceding follow-up visit.
• Current smokers. Ex-smokers must not have smoked for a minimum of 12 months, and should not have a smoking history ≥10 pack years. Subjects who administer nicotine in other forms (patches, chew tobacco, electronic cigarettes, etc.) will also be excluded from the study;
• Concomitant disease or condition which could interfere with the conduct of the study, or for which the treatment might interfere with the conduct of the study, or which would, in the opinion of the investigator, pose an unacceptable risk to the subject in this study, including, but not limited to, cancer, alcoholism, drug dependency or abuse, or psychiatric disease.
• Pregnant or lactating women at the time of follow-up visit.

Asthmatic subjects with at least two sputum cell differential results > 1 year before follow-up visit