When are biomarkers useful in the management of airway diseases?

Biomarkers are characteristics that are objectively measured and evaluated as indicators of biological or pathogenic processes, or responses to therapeutic interventions, and may provide information on the prognosis or progression of the disease and response to treatment. They are likely to be helpful in the management of airway diseases because of the heterogeneity of their pathobiology. Most biomarkers have been developed and evaluated to assess the airway inflammation (or bronchitis) associated with airway diseases. These include quantitative cell counts in sputum, fraction of nitric oxide in exhaled breath, and various metabolites in exhaled breath. This review provides a brief description of these biomarkers with a particular emphasis on how eosinophil and neutrophil counts in sputum could be used to manage airway diseases such as asthma, chronic obstructive pulmonary disease, and chronic cough.