Disease burden of eosinophilic airway disease: Comparing severe asthma, COPD and asthma–COPD overlap

There is less understanding of phenotypes and disease burden in asthma‐COPD overlap (ACO) than either disease alone. Blood eosinophils may help identify the patients in the clinic with eosinophilic airway inflammation. The potential value of this approach requires an understanding of the illness burden associated with eosinophilic ACO, eosinophilic severe asthma and eosinophilic COPD, defined by blood eosinophils.