Box 1.

Classification of asthma phenotypes in children [4]

Symptom based

• Age at onset

• Natural history

• Severity

Trigger based

• Allergic vs. non-allergic

• Exercise induced

• Viral triggered vs. multi triggered.

Response to treatment

• Corticosteroid responsive

Inflammatory features (based on biopsy, induced sputum and bronchoalveolar lavage)

• Eosinophilic

• Neutrophilic

Non-invasive markers

• Exhaled nitric oxide

• Exhaled breath condensate

Pulmonary function tests

• Fixed vs. bronchodilator-reversible airway obstruction

• Bronchial responsiveness to exercise, cold air, chemical challenge.