Definitions, causes, course, and prognosis of chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is a common disorder that is related to smoking in susceptible individuals. The epidemiology is complex and includes both environmental and host factors. Early identification and intervention via smoking cessation and possibly the augmentation of antioxidant defenses in the lung offer hope to prevent and forestall premature morbidity and mortality for this fourth most common cause of death in the United States.