Redefining the overlap of asthma and COPD.

The term asthma-COPD overlap (ACO) has been suggested for people with chronic airflow obstruction that has features characteristic of both asthma and chronic obstructive pulmonary disease (COPD).1 People with clinical features of asthma and COPD tend to have worse outcomes than those with either asthma or COPD alone, yet their clinical management has remained unclear. UK guidelines currently do not specifically address this issue,2,3 but the Global Initiative for Asthma (GINA) and the Global Initiative for Chronic Obstructive Lung Disease (GOLD) have published a consensus-based report on the diagnosis and treatment of people with asthma, COPD and ACO.1 Although 'asthma-COPD overlap syndrome' (ACOS) was briefly used, some thought that it gave the unhelpful impression that it referred to a single disease entity. Here, we consider some of the challenges in managing this heterogeneous group of patients.