Others [27] found a relationship between FENO50 of 19 ppb and
sputum eosinophils (3%) in a series of patients hospitalized for
COPD exacerbation and [28] in predicting eosinophilic airway
inflammation in patients with chronic cough. Our study shares
results with these studies, but differs from them in terms of the
characterization of ACOS with strict criteria (that are not all related
to the previous history of asthma, as another guidelines do) published
before and included in GesEPOC guidelines, allowing the
clinician to differentiate COPD phenotypes with simple and non
invasive tests than can be used in ambulatory assistance.