Abstract
Asthma-Chronic obstructive pulmonary disease overlap syndrome (ACOS) or ASCOS is a frequently encountered clinical syndrome. It is identified by the clinical features that it shares with asthma and COPD. There is no clear consensus definition yet for this medical syndrome. ACOS has not been extensively studied partly because of the absence of clarity of its clinical significance and because of the lack of a clear definition for this syndrome. ACOS is characterized by persistent airflow limitation with several features usually associated with asthma and several features usually associated with chronic obstructive pulmonary disease (COPD). It has been described and named differently by different authors. Some of the commonly encountered names are asthmatic bronchitis, asthma of the elderly, patients with COPD and a prominent asthmatic component, asthma that complicates COPD, asthma with permanent obstruction, COPD with a reversible component and asthma-COPD overlap syndrome. In most obstructive lung disease trials patients with overlap syndrome are excluded because they are not strictly asthmatic per the study inclusion criteria or they are not strictly chronic obstructive pulmonary disease patients. With no clear consensus on the definition and few studies on its genetics or pathophysiology, it is difficult to create management guidelines for this group of patients. Patients with ACOS have been found to have higher risk not only for exacerbations, but also for hospitalizations. Global Initiative for Chronic Obstructive Lung Disease (Gold) and the Global Initiative for Asthma (GINA) have suggested a stepwise diagnostic and management criteria for patients with ACOS.
Highlights
Asthma-chronic obstructive pulmonary disease (COPD) overlap syndrome is a frequently encountered clinical condition which has not been precisely defined by the pulmonary community partly due to inadequate clinical studies
In the past decade or so, several attempts have been made in the United States, Spain, Japan, Greece, and Canada to better define and classify Asthma-Chronic obstructive pulmonary disease overlap syndrome (ACOS).[2,3,4], Asthma which is a reversible obstructive lung disease and COPD, which is a non-reversible obstructive lung disease have been clearly defined and studied, but in clinical practice, there is a hybrid disease between asthma and COPD
The fact that older people with asthma or asthmatics who are smokers have a lower response to corticosteroids may just be one of the reasons why there is a need for more studies on ACOS
Summary
Asthma-COPD overlap syndrome is a frequently encountered clinical condition which has not been precisely defined by the pulmonary community partly due to inadequate clinical studies. American Thoracic Society first attempted to characterize this syndrome decades ago, and they described it as asthmatic bronchitis.[1] For several years after the initial definition, no studies to the best of our knowledge were completed to better understand ACOS. In the past decade or so, several attempts have been made in the United States, Spain, Japan, Greece, and Canada to better define and classify ACOS.[2,3,4], Asthma which is a reversible obstructive lung disease and COPD, which is a non-reversible obstructive lung disease have been clearly defined and studied, but in clinical practice, there is a hybrid disease between asthma and COPD. Soriano et al analyzed data from NHANES and found that ACOS is common among older patients from
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