Intense Airway Eosinophilia in Asthma

Inclusion Criteria: * Aged 18 years and over * With a proven diagnosis of asthma as defined by one of the above criteria of current guidelines (36): 1. Forced expiratory volume in one second (FEV1) increase by at least 12% (and ≥200 ml) after administration of a bronchodilator 2. Current asthma symptoms and a methacholine provocative concentration inducing a 20% fall in FEV1 (PC20) \<16 mg/ml 3. A respirologist's current diagnosis of asthma found in the patient's medical report 3. Non-smokers or smokers/ex-smokers defined as someone with a smoking history \<10 pack-years 4. With sputum differential cell count result 5. Considered to receive optimal treatment for their disease (as per current guidelines except for patients included in exploratory objective 1. 6\. Stable asthma and asthma medication for at least 4 weeks before data analysis 7. Written informed consent obtained for inclusion in the database Exclusion Criteria: 1. Any respiratory disease apart from asthma 2. Current or ex-smokers should not have a smoking history ≥10 pack-year before data analysis. Patients who administer nicotine in other forms (patches, chew tobacco, e-cigarette, etc.) will be excluded 3. Unstable asthma medication \<4 weeks before data analysis 4. Asthma exacerbation (see definition below) \<4 weeks before data analysis 5. Respiratory tract infection \<4 weeks before data analysis