The usefulness of biomarkers of airway inflammation in managing asthma.

The goal of managing asthma is to maintain disease control. Current approaches to assessment of control do not include measurement of airway inflammation. This study was designed to assess the usefulness of biomarkers of airway inflammation in guiding asthma management decisions. A literature review was performed. Bronchial biopsy is a direct measure of airway inflammation but not practical for routine use. Enumeration of sputum eosinophils is very useful in guiding changes in controller medication to decrease asthma exacerbations, whereas measurement of exhaled nitric oxide has not proven to be useful in this regard. Serial measurement of airway hyperreactivity as a guide to asthma management yields inconclusive results. Use of indirect stimuli for bronchial challenge offers both practical and theoretical advantages in the assessment of airway hyperreactivity. Data on the analysis of exhaled breath condensate have not yet been studied adequately in guiding management decisions. Enumeration of sputum cell counts appears to be the most useful biomarker of airway inflammation in guiding asthma management decisions. Combined approaches using simple methods of measuring airway hyperreactivity and obtaining sputum samples hold promise for the future, particularly if rapid analysis of cellular products in sputum can be developed.