Lung Health Study (LHS) I and III

BACKGROUND:

Chronic obstructive pulmonary disease (COPD) is a major cause of mortality and morbidity in the United States, affecting nearly 10 million persons. COPD accounts for 60,000 deaths yearly and ranks as the fourth leading cause of death. If current trends continue, it may become the nation's fourth or even third leading cause of death by the year 2000.

Epidemiological studies consistently indicated that smoking was the over-whelming risk factor for accelerated decline in pulmonary function and subsequent development of COPD. Furthermore, evidence from several studies indicated that the rate of decline in pulmonary function approached a more normal rate of decline upon cessation of cigarette smoking.

Another presumed risk factor for accelerated decline in pulmonary function was the presence of hyperreactive airways, although it was not clear whether the mere presence of hyperreactive airways contributed to the accelerated decline, or whether the decline resulted from the reaction of the airways to various irritants over a long period of time. It is possible that if the hyperreactive airway was kept non-reactive by pharmacological means over a period of years, the expected abnormal decline might be lessened. This effect might be enhanced by the cessation of cigarette smoking.

Although the evidence was strong that smoking and hyperreactive airways were risk factors for COPD, it had not been demonstrated whether removal of risk factors at a stage when mild dysfunction had already occurred would effectively modify the course of COPD.