**9. Conclusions**

ACOS is the coincidence of asthma and COPD in the same individual. Prospective studies are required to analyze the underlying inflammatory mechanisms in this entity. So we think that longitudinal studies are required to validate the diagnostic criteria and identify biomarkers of the disease. It also remains to be determined if it has different prognostic and therapeutic implications. If so, perhaps in the future, ACOS will be considered a distinct endotype of chronic obstructive airway disease. There is also a lack of studies to further clarify the best therapeutic options for patients with ACOS. At this moment, it seems reasonable to consider the combination of an ICS and a long-acting β-agonist as the first-choice therapy for these patients.
