ABSTRACT
Obstructive lung diseases, particularly chronic obstructive pulmonary disease (COPD), are one of the main causes of morbidity and mortality in developed countries. It is estimated that more than 15 million persons in the United States suffer from COPD and more than 12 million from chronic bronchitis (1). Furthermore, the number of individuals affected has grown over recent decades. The age-adjusted mortality rate from COPD doubled from 1970 to 2002 in the United States, whereas rates from stroke and heart disease decreased by 63% and 52%, respectively (2).
