Long-term risk factors for developing asthma and allergic rhinitis: a 23-year follow-up study of college students.

In the initial study of 23 years ago, 1836 college freshmen were prospectively evaluated by questionnaires, interviews, and physical examinations for medical conditions which included the presence of asthma, allergic rhinitis, and positive allergy skin tests to a battery of pollens, animal extracts, and mold. In a 23-year follow-up study, 1021 (64%) returned their completed questionnaires. Of these, 738 (72%) had been skin tested as freshmen. The results of this follow-up study revealed that the frequency of asthma and allergic rhinitis continue to increase as the individuals become older. Allergic rhinitis and positive allergy skin tests are significant risk factors for developing new asthma. Individuals with either of these diagnoses are about three times more likely to develop asthma than negative controls. Positive allergy skin tested students have more than twice (2.3x) the risk of developing new hay fever than do negative skin tested students over a 23-year period.