Chronic cough is also an important entity in patients with eosinophilic bronchitis and the condition has two
important similarities with asthma
Presence of an eosinophilic airway infiltrate
Response to corticosteroids
There is no evidence of variable airflow obstruction or bronchial hyper-reactivity in patients with eosinophilic bronchitis but there is evidence of basement membrane thickening and elevated levels of exhaled nitric oxide that is reflective of airway eosinophilia
Patients with eosinophilic bronchitis, by definition, have sputum eosinophilia >3%