Diagnosis of asthma-COPD overlap: the five commandments.

There is wide consensus regarding the excessive use of inhaled corticosteroids (ICS) in chronic obstructive pulmonary disease (COPD) [1, 2]. The approved indication for ICS in COPD is the treatment of patients with impaired lung function (usually forced expiratory volume in 1 s (FEV1) <60% predicted) and frequent exacerbations, but the recent Global Initiative for Chronic Obstructive Lung Disease (GOLD) strategic document indicates that even in these cases, dual bronchodilation should be preferred to the use of a combination containing ICS. However, long-acting β2-agonists/ICS may be the first choice of treatment in patients with a history and/or findings suggestive of asthma–COPD overlap (ACO) and/or high blood eosinophil counts [3]. Therefore, the history and/or findings of ACO are crucial for the therapeutic decision to prescribe an ICS or not in COPD but no clear indication is provided about what history and/or findings of ACO mean [3], and this has been highlighted as one of the limitations of the new proposal for pharmacological treatment [4]. In addition, the same document indicates that regular treatment with ICS increases the risk of pneumonia [3]. Therefore, the clinician must evaluate the risk/ benefit ratio in each patient before the prescription of an ICS, and the diagnosis of ACO plays a fundamental role in this evaluation. In contrast, the diagnosis of ACO does not have significant therapeutic implications in asthma because the initial therapy is not different between pure asthmatics and overlap patients.