The Nurse Practitioner • February 2022 25 sthma-COPD overlap (ACO) presents in persons (primarily adults) with persistent airfl ow limitation along with clinical symptoms refl ective of both asthma and chronic obstructive pulmonary disease (COPD). This is a term that encompasses many clinical phenotypes with disparate underlying pathophysiology. Patients with ACO have various clinical symptoms and pathways, which embody a heterogenous, composite infl ammatory process that is poorly understood. 1 A 2021 systematic review and meta-analysis concluded that patients with ACO have a higher number of exacerbations per year than