| Methods based on clinical features |
| Symptom based |
| Age at onset |
| Natural history |
| Severity |
| Defined by triggers |
| Allergic versus non-allergic |
| Exercise induced |
| Viral-triggered versus multi-triggered wheeze |
| Response to treatment |
| Corticosteroid responsive |
| Methods based on pathophysiological features |
| Pathological tests (biopsy, induced sputum & bronchoalveolar lavage) |
| Eosinophilic |
| Neutrophilic |
| Non-invasive markers of airway inflammation |
| Exhaled nitric oxide |
| Exhaled breath condensate |
| Pulmonary function tests |
| Fixed versus bronchodilator-reversible airway obstruction |
| Bronchial responsiveness to exercise, cold air, chemical challenge |