Page 45 - ADULT-ONSET ASTHMA PREDICTORS OF CLINICAL COURSE AND SEVERITY

BIOMARKERS TO IDENTIFY SPUTUM EOSINOPHILIA IN DIFFERENT ADULT ASTHMA PHENOTYPES
INTRODUCTION
Eosinophilic airway in amma on is an important dis nguishing characteris c of speci c adult asthma phenotypes 1. To assess this type of airway in amma on, sputum eosinophil counts are generally considered as the gold standard 2. Treatment guided by sputum eosinophils reduces the frequency of asthma exacerba ons 3 and pa ents with sputum eosinophilia have a be er response to inhaled cor costeroids with respect to reducing airway hyperresponsiveness, decreasing asthma symptoms and improving quality of life compared to those without 4, 5. Not surprisingly, the recent ATS/ERS guidelines on severe asthma recommend sputum eosinophils combined with clinical criteria to guide asthma therapy 6. Unfortunately, sputum induc on and di eren al sputum cell counts are only feasible in specialized clinics, are not always successful and do not give immediate results 7.
Several alterna ve methods to assess airway eosinophilia have been proposed in the literature, including non-invasive biomarkers such as the frac on of exhaled nitric oxide (FeNO) 8-10, peripheral blood eosinophil counts 10, 11 and total immunoglobulin E (IgE) 10, with varying diagnos c accuracy. However, speci c pa ent characteris cs that dis nguish between di erent adult asthma phenotypes such as asthma severity 12, obesity 13, atopy 14, and (ex-)smoking status 15 may in uence both airway and systemic in amma on. Therefore, the accuracy of biomarkers to assess sputum eosinophilia may vary between these di erent asthma phenotypes.
The aim of the present study was to evaluate the diagnos c accuracy of FeNO, blood eosinophils and total IgE for detec ng sputum eosinophilia, de ned as ≥3% 16, 17 in a large heterogeneous group of adult asthma pa ents, as well as in pa ents with di erent asthma phenotypes.
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