The student will be able to summarize the definition, prevalence, and impact of chronic obstructive pulmonary disease (COPD) in the United States and worldwide.
The student will be able to list the primary host and environmental risk factors for development of COPD.
The student will be able to describe the pathophysiology of COPD, distinguish its clinical features, and the guidelines for its treatment and prevention.
The World Health Organization (WHO) estimates that 210 million people have chronic obstructive pulmonary disease (COPD) worldwide, with more than 3 million dying from the disease annually. COPD is the fourth leading cause of mortality in the United States among patients older than 45 years of age, and causes 5% of deaths worldwide. Moreover, COPD mortality is expected to increase by more than 30% over the next decade if current trends in tobacco smoking persist. Despite its increasing prevalence, COPD remains undiagnosed in many patients, thereby delaying important interventions that can prevent death and ameliorate symptoms and disability in those affected.
Working Definition of COPD
The Global Initiative for Obstructive Lung Disease (GOLD) Guidelines define COPD as a "preventable and treatable disease with some cardiopulmonary effects that may contribute to the severity in individual patients. Its pulmonary component is characterized by airflow limitation that is not fully reversible. The airflow limitation is usually progressive and associated with an abnormal inflammatory response of the lung to noxious particles and gases." Clinically, COPD encompasses the disorders of chronic bronchitis and emphysema, features of which may overlap with one another in individual patients. Chronic bronchitis is clinically defined as a cough productive of sputum most days of the month, at least 3 months of the year for two successive years without other explanations. In contrast, emphysema is anatomically defined by inflammation and abnormal enlargement of alveolar sacs, ducts, and walls distal to the terminal bronchioles of the small airways. Application of these histopathologic guidelines is summarized in Chap. 20.
A meta-analysis of multiple trials and studies that was conducted in 2004 estimated the worldwide prevalence of COPD to be approximately 7.6%. In the United States, where there are up to 24 million individuals with active or previous smoking histories, the estimated prevalence in adults aged 25-75 years is 6.9% for mild COPD (defined as FEV1/FVC <70% and FEV1 ≥80% predicted), and 6.6% for moderate COPD (FEV1/FVC <70% and FEV1 <80% predicted). These prevalences were established by the National Health and Nutrition Examination Survey III (NHANES-III). Furthermore, the Global Burden of Disease Study has projected that COPD will become the fifth leading cause of disability-adjusted life years lost by the year 2020.
Major Risk Factors for Development of COPD
The risk factors for COPD include both host and environmental factors (Table 22.1). With respect to host factors, ...