Peripheral eosinophil count as a biomarker for the management of COPD: not there yet.

Chronic obstructive pulmonary disease (COPD) is associated with acute and chronic pulmonary as well as systemic inflammation [1]. Anti-inflammatory treatments, such as inhaled corticosteroids (ICS) and oral roflumilast, are recommended for COPD patients [2]. These drugs are effective agents for the prevention of COPD exacerbations and improvement of lung function and have various effects on health status, but they are associated with adverse events, the most concerning being pneumonia (ICS) and diarrhoea (roflumilast).