Asthma and Chronic Obstructive Pulmonary Disease

Asthma and chronic obstructive pulmonary disease (COPD) are both highly prevalent diseases worldwide. This issue of Clinics in Chest Medicine discusses different aspects of COPD, but in addition, the present article on overlap and differential signs and symptoms with asthma has been included. This is appropriate because it is often difficult to differentiate asthma from COPD, particularly at older ages. At that time in life, patients with asthma may have developed persistent airway obstruction, a characteristic that is a prerequisite for diagnosis of COPD according to the GOLD (Global Initiative for Chronic Obstructive Lung Disease) criteria. This feature would not be a problem if asthma and COPD had the same clinical prognosis and response to pharmacologic treatment, and required similar management of the disease in clinical practice. However, this is often not the case. Asthma and COPD have been defined over the years in many different ways, and the heterogeneity in definitions in the literature contributes to the difficulty of evaluating evidence about the extent to which they overlap. The problem is confounded by the necessary reliance in many epidemiologic studies on self-reported diagnosis of asthma and COPD, and because, in clinical practice, these diagnoses are often assigned without lung function testing having been performed.