To demonstrate the lack of evidence and clinical usefulness of the notion of ‘asthma-COPD overlap syndrome’ (ACOS). Asthma and chronic obstructive pulmonary disease (COPD) are two separate and different illnesses. Physicians have known for many years that asthma and COPD may coexist in certain individuals. When a person exhibits clinical symptoms of both asthma and COPD, the name ACOS has recently been adopted. However, the lack of a precise diagnosis has resulted in inconsistencies in reported frequency, prognosis, and treatments. Even now, no phenotypic characterisation of ACOS has been established, despite the fact that it is part of the total complexity and variety of COPDs. There is a lack of high-quality evidence on which to base ACOS therapy recommendations. As a result, therapy in clinical practice is extrapolated from the existing information on asthma and COPD.

The present definition of ACOS appears clinically useless, as it has little bearing on the prognosis or management of these individuals. The authors concluded that the name ACOS should be avoided in individuals who have symptoms of both asthma and COPD.