Table 5. Biomarkers for identifying type 2 inflammation: advantages and disadvantages.
| Biomarker | Advantages | Disadvantages |
|---|---|---|
| Serum IgE | • Easy to measure | Does not predict omalizumab responsiveness |
| • Identifies candidates for omalizumab therapy | ||
| Sputum eosinophils | • ERS/ATS recommended to guide treatment, along with clinical criteria | Technically challenging to perform; some patients cannot provide adequate samples |
| • Adjusting therapy based on sputum eosinophils was validated for reducing exacerbation frequency in adults | ||
| Blood eosinophils | • Correlated with sputum eosinophilia | Optimal cutoff not established |
| • Easy to measure | ||
| • ≥ 300 cells/μL, ↑ risk of asthma attacks, asthma-related ED visits | ||
| • ≥ 400 cells/μL, ↑ rate of severe exacerbations | ||
| FeNO | • Correlated with sputum and blood eosinophils | Not recommended for guiding therapy in patients with severe asthma |
| • ≥ 50 ppb, ↑ risk of asthma attacks, asthma-related ED | ||
| • Adjusting therapy based on FeNO reduced the risk of asthma exacerbation | ||
| Serum periostin | • Markers of airway eosinophilia and IL13 activity | Not specific to asthma |
ED, emergency department; ERS/ATS, European Respiratory Society/American Thoracic Society; FeNO, fractional exhaled nitric oxide; IgE, immunoglobulin E; IL, interleukin.