to determine whether asthma alone can cause irreversible airflow obstruction 42 men and 47 women with chronic asthma ( mean duration 22 ( sd 13 ) years ) without evidence of other disease likely to cause irreversible airflow obstruction were treated with theophylline orally and a beta agonist both orally and by inhalation for four weeks .
C0004096
asthma
C0039771
theophylline