Techniques to be considered for investigation of asthma-related comorbidities
| Allergy skin testing |
| Rhinoscopy |
| Sinus radiography/computed tomography |
| Sputum bacteriological testing |
| Therapeutic trial of GERD with proton pump inhibitor or pH probe |
| Sleep studies |
| Precipitins for Aspergillus |
| Pulmonary function tests (including lung volume and DL,CO) |
| Chest radiography/computed tomography |
| Bronchoscopy with or without bronchoalveolar lavage |
| Laryngoscopy |
| Psychological evaluation |
| Induced sputum cell counts |
Additional tests may be required. GERD: gastro-oesophageal reflux disease; DL,CO: diffusion capacity of the lung for carbon monoxide.