Epidemiology

COPD is now the fourth most common cause of death in the United States. It is the only cause of death among the top 10 that continues to rise. In 2000, there will be approximately 115,000 deaths from COPD. In 1994, there were 500,000 hospitalizations, 14 million office visits, and 114 million patient days of restricted activity from COPD in the United States. The medical costs from COPD are also increasing among the elderly population.

COPD can be considered a smoker's disease that clusters in families and worsens with age. The hereditary patterns that contribute to COPD have not been identified, except in the case of alpha-1-antitrypsin deficiency (Discussed in Section D).

The risk factors for COPD are genetic, constitutional, behavioral, socioeconomic, and environmental. Tobacco smoke and occupational hazards, when present, should be eliminated since they are the two major external factors that can be altered. However, constitutional risk factors cannot be changed. It has been estimated that 80% to 85% of COPD cases in the United States are attributable to tobacco smoking. In addition, smoking cessation slows the decline in expiratory airflow. This clearly shows that smoking or its cessation is a powerful factor determining a patient's outcome. Other contributing factors in COPD include air pollution, childhood respiratory infections, and nonspecific bronchial hyperreactivity.

Morbidity and mortality from COPD are more common in whites compared with blacks, and in men compared with women. Figure 1 presents the death rates for COPD by age, sex, and race in the United States in 1997. While the number of men who die from COPD annually is beginning to drop slightly, the number of COPD deaths in white and black women have increased steadly since 1980, probably because of increased smoking in this group (See Figure 2). The prevalence of COPD in developed countries is similar to that in the United States. Elsewhere in the world it is not well defined, but limited data from Asia (par-ticularly India and China) suggest a high prevalence of the disease in these places (See Figure 3).

At least 16 million persons in the United States have symptomatic COPD. The third National Health and Nutrition Examination Survey, (nhanes iii), estimates that at least another 16 million people in the United States have asymptomatic, undiagnosed COPD. Thus, in all, COPD probably affects 30 to 35 million people in the U.S. Accordingly, it is incumbent upon all primary care physicians to be alert to the possibility of COPD in patients with productive cough, particularly in those who suffer exercise-related dyspnea and have a family history of the disease, and definitely in those who are smokers. COPD must be identified early by simple spirometric measurement as discussed in Section F.

References

Health, United States, 1999. U.S. Department of Health and Human Services, Centers for Disease Control and Prevention. 1999 DHHS Publication #99-1232 pp179-180. Mortality statistics related to COPD.

Higgins M. Risk factors associated with chronic obstructive lung disease. Ann NY Acad Sci 1991;642:7-17. This is a recent review of all of the known risk factors for COPD.

Janoff A. Elastase and emphysema: Current assessment of the protease-antiprotease hypothesis. Am Rev Respir Dis 1985;132:417-433. A state-of-the-art review of the elastase mechanisms involved in the pathogenesis of emphysema and COPD.

Peto R, Speizer FE, Cochrane AL, et al. The relevance in adults of airflow obstruction, but not of mucus hypersecretion, to morbidity from chronic lung disease. Am Rev Respir Dis 1983;128:491-500. A classic article discussing the favorable effect of stopping smoking on the rate of decline in fev1 and on survival during a 20-year follow-up.

Petty TL. Chronic obstructive lung disease and other conditions of the chest. Chapter 55 in Matzen RN, Lang RL (eds). Clinical Preventive Medicine. St. Louis: CV Mosby, 1993. A complete review on methods for preventing premature morbidity and mortality in COPD and related disorders.