These findings appear in the May 1 issue of the American Journal of Respiratory and Critical Care Medicine, published by the American Thoracic Society.
David Mannino, M.D., of the University of Kentucky Medical Center, and two associates found that patients with advanced COPD and rapid lung function decline are 10 times more likely to die than individuals with normal lung function.
COPD, an important cause of hospitalization and death, results from persistent obstruction of the airways associated with either severe emphysema or chronic bronchitis. In emphysema, the tiny air sacs of the lung (alveoli) become enlarged and their walls are destroyed. In chronic bronchitis, the bronchial glands enlarge, causing chronic cough and excess mucus. Ten to 15 percent of all smokers develop COPD as a result of irritants in tobacco that causes inflammation of the alveoli.
Over the course of three years, the investigators analyzed 13,756 middle-aged adults, all of whom participated in the 1986 Atherosclerosis Risk in the Communities Study and provided baseline information on respiratory symptoms and diseases. The researchers tested the participants' lung function twice--once at the start of the study and during a follow-up three years later.
The authors classified patients with the worst lung function as "rapid decliners." Twenty-five percent of the entire study population (3,437 individuals) fell into this high-mortality category. Of the 720 subjects who died during the study, 273 (38 percent) were considered "rapid decliners."
In addition, patients in advanced stages of COPD who were also "rapid decliners" were hospitalized at rate 40 times higher than those with normal lung function at baseline who had no rapid lung decline over the three-year period.