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Different asthma-COPD overlap definitions identify different patient populations

Published online: April 26, 2019

The term "asthma-COPD overlap” (ACO) was introduced in the last decade to characterize patients presenting features of both asthma and chronic obstructive pulmonary disease (COPD). Several different definitions of ACO have been proposed, including the definition presented by two leading expert panels: Global Initiative for Asthma and Global Initiative for Chronic Obstructive Pulmonary Disease (GINA/GOLD). Certain differences in the proposed diagnostic criteria have resulted not only in a wide range of the reported incidence of ACO incidence but also caused some uncertainty whether these criteria identify the same populations of patients.

In an article recently published in The Journal of Allergy and Immunology: In Practice, Barczyk and colleagues assessed the distribution of patients with ACO in a large population of patients with chronic airway disease (asthma, COPD or its components – emphysema and/or chronic bronchitis) based  on five commonly used definitions of this condition. Approximately one third of the investigated patients met the criteria for at least one ACO definition. The researchers found that each of the analyzed ACO definitions identified almost distinct populations of patients, with a very limited number of patients who met the criteria for more than one definition. The study showed that even a small change in the diagnostic criteria may cause a considerable difference in the number of patients in the identified ACO population. ACO prevalence varied in the same patient population depending on ACO definition used. There was a weak agreement between the definitions. Furthermore, ACO patients identified with different definitions reported different levels of symptom severity.

These data show that a precise, reliable ACO definition is still lacking and that results of research on ACO should be interpreted and compared only in the context of the ACO definition used in the study.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.