FINDINGS BEFORE THE DIAGNOSIS OF ASTHMA IN YOUNG-ADULTS

Background: Asthma is a poorly understood disease. Risk factors are not established, and the natural history of the disease is unknown. Objective: Using subjects of a community-based study, we have prospectively compared young adults destined to develop asthma with control subjects to determine differences between them before diagnosis. Methods: Subjects were participants of the Tucson Epidemiologic Study of Airways Obstructive Disease. They were studied between the ages of 15 and 19 and subsequently every 1 to 2 years until they were at least 21 years old with questionnaires, spirometry, allergy skin testing and serum IgE testing. Results: Logistic regression showed chat ''wheeze'' and ''attacks of shortness of breath with wheeze'' were independently predictive of asthma. Positive allergy skin test results occurred more frequently among subjects who later received a diagnosis of asthma, and initially these subjects had higher serum IgE levels than control subjects (geometric mean IgE = 173.8 IU/ml vs 52.5 IU/ml for control subjects; p < 0.005). Although initial spirometric testing did not distinguish between future asthmatic subjects and control subjects, repeat testing after diagnosis did show significant differences in flows at low lung volumes. Conclusions: These data suggest chat symptoms and findings suggestive of asthma may be present for many years before diagnosis.