Asthma is a chronic inflammatory airways disorder mainly characterized by heterogeneity. In the more severe forms, a discordance often exists between symptoms and inflammation. Difficulty in managing asthma derives partly from the multiple phenotypes existing and our inability to recognize them. The use of non-invasive, with main representative the fraction of exhaled nitric oxide, or semi-invasive techniques such as induced sputum are effective tools that can help us to guide asthma treatment. In the latest years, several serum biomarkers related to asthmatic inflammation have been used for the better recognition of asthma sub-phenotypes to achieve optimization of therapy and disease outcome. In patients with mild-moderate asthma, as well as patients with more severe asthma, the use of blood eosinophils revealed an acceptable accuracy for the prediction of airway eosinophilia indicating that in future studies may facilitate both individualized treatment and management of asthma. None of the above techniques have been incorporated in clinical practice although sputum eosinophils can be used in patients with severe asthma particularly in specialized centers with great experience. Of great interest are blood eosinophils since current data support their role either as tool for treatment selections or/and as a biomarker of airway eosinophilia.
Keywords: Asthma; Biomarkers; Eosinophils; Sputum; Strategy; Treatment.