When Asthma and Chronic Obstructive Pulmonary Disease Overlap; Current Knowledge and Unmet Needs.

Asthma and chronic obstructive pulmonary disease (COPD) are common diseases that often overlap. The term asthma-COPD overlap (ACO) has been used to define this entity but there remain several speculations on its exact definition, impact, pathophysiology, and clinical features. Patients with ACO have greater morbidity than those with asthma or COPD alone, but the information on the best therapeutic approach to this group of patients is still limited. Current treatment recommendations rely on expert opinions, roundtable discussions, and strategy documents. It is prudent to examine existing knowledge about ACO and determine the path for future research.