The chronic obstructive pulmonary disease‐asthma overlap syndrome

When asthma and chronic obstructive pulmonary disease (COPD) occur together the term COPD‐asthma overlap syndrome has been applied. To date, there is no universally accepted definition of this overlap syndrome, just as there is no blood test or other technologic assessment that provides a simple way to distinguish asthma from COPD. One practical approach to the overlap diagnosis has been to include patients with a diagnosis of COPD by Global Initiative for Chronic Obstructive Lung Disease criteria and asthma defined by subject report of a physician diagnosis of asthma before the age of 40 years. Alternatively, it includes patients who meet criteria for COPD (fixed airflow obstruction) and who also have typical features of asthma (wheezing, atopy, eosinophilia, and positive bronchodilator response on spirometry). Compared with patients with COPD alone, the overlap patients are younger with less smoking intensity, have higher health-care utilization, have a worse disease-related quality of life, and have a higher mortality. Treatment with corticosteroids earlier in the course of the disease compared with the patient with only COPD has been recommended.