ABSTRACT
Asthma and chronic obstructive pulmonary disease (COPD) are a huge medical burden worldwide. There are 330 million people globally with asthma and another 384 million individuals with COPD. COPD accounts for 5% of all deaths globally (3 million per year). 1 The most recent estimates suggest that 1 in 12 people have one or both of these disorders. 2,3 Asthma and COPD are distinct disorders, which share some similar clinical features including symptoms (e.g. dyspnea, wheezing, and cough) and airflow limitation. In asthma, however, the airflow limitation tends to be episodic with complete or near complete reversibility during periods of stability or with treatment. 2 The airflow limitation associated with COPD, on the other hand, tends to be persistent, nonreversible, or incompletely reversible, and is often progressive. 3 Some individuals demonstrate clinical features of both asthma and COPD and thus have been recently labeled as patients with asthma-COPD overlap (ACO). The details on ACO epidemiology, definition, and pathophysiology have been discussed in previous chapters. Here, we will focus largely on clinical presentations, health-related quality of life (HRQL) and prognosis of patients with ACO in the context of asthma and COPD, including discussion of a case study that will illustrate the most salient features of ACO on these domains.
