Mekov,Evgeni, Nuñez,Alexa, Sin,Don D, Ichinose,Masakazu, Rhee,Chin Kook, Maselli,Diego Jose, Coté,Andréanne, Suppli Ulrik,Charlotte, Maltais,François, Anzueto,Antonio, and Miravitlles,Marc
Evgeni Mekov,1 Alexa Nuñez,2 Don D Sin,3 Masakazu Ichinose,4 Chin Kook Rhee,5 Diego Jose Maselli,6 Andréanne Coté,7 Charlotte Suppli Ulrik,8,9 François Maltais,7 Antonio Anzueto,6 Marc Miravitlles2 1Department of Occupational Diseases, Medical Faculty, Medical University of Sofia, Sofia, Bulgaria; 2Pneumology Department, Hospital Universitari Vall d´Hebron, Vall d’Hebron Institut de Recerca (VHIR), Vall d’Hebron Barcelona Hospital Campus, CIBER de Enfermedades Respiratorias (CIBERES), Barcelona, Spain; 3Centre for Heart Lung Innovation, St. Paul’s Hospital, Department of Medicine (Respiratory Division), University of British Columbia, Vancouver, BC, Canada; 4Academic Center of Osaki Citizen Hospital, Miyagi, Japan; 5Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea; 6Division of Pulmonary Diseases & Critical Care, University of Texas Health, South Texas Veterans Health Care System, San Antonio, TX, USA; 7Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, QC, Canada; 8Department of Pulmonary Medicine, Copenhagen University Hospital-Hvidovre, Hvidovre, Denmark; 9Institute of Clinical Medicine, University of Copenhagen, Copenhagen, DenmarkCorrespondence: Marc MiravitllesPneumology Department, Hospital Universitari Vall d´Hebron, Vall d’Hebron Institut de Recerca (VHIR), Vall d’Hebron Barcelona Hospital Campus, CIBER de Enfermedades Respiratorias (CIBERES), Barcelona, SpainEmail marcm@separ.esAbstract: Although chronic obstructive pulmonary disease (COPD) and asthma are well-characterized diseases, they can coexist in a given patient. The term asthma–COPD overlap (ACO) was introduced to describe patients that have clinical features of both diseases and may represent around 25% of COPD patients and around 20% of asthma patients. Despite the increasing interest in ACO, there are still substantial controversies regarding its definition and its position within clinical guidelines for patients with obstructive lung disease. In general, most definitions indicate that ACO patients must present with non-reversible airflow limitation, significant exposure to smoking or other noxious particles or gases, together with features of asthma. In patients with a primary diagnosis of COPD, the identification of ACO has therapeutic implication because the asthmatic component should be treated with inhaled corticosteroids and some studies suggest that the most severe patients may respond to biological agents indicated for severe asthma. This manuscript aims to summarize the current state-of-the-art of ACO. The definitions, prevalence, and clinical manifestations will be reviewed and some innovative aspects, such as genetics, epigenetics, and biomarkers will be addressed. Lastly, the management and prognosis will be outlined as well as the position of ACO in the COPD and asthma guidelines.Keywords: ACO, asthma, COPD, epidemiology, genetics, biomarkers, prognosis, treatment