Secular trends of allergic asthma in Danish adults. The Copenhagen AllergyStudy

Numerous studies have reported increases in asthma prevalence among childre n world-wide. Less is known about similar trends in adults. We aimed To inv estigate whether the prevalence of allergic asthma symptoms had increased i n an adult general population. Two cross-sectional surveys using identical methods were carried out in 198 9 and 1998. A one-page questionnaire on respiratory symptoms was mailed to random samples of 15-41-year-olds living in Copenhagen. The response rates were 86.6% (3624/4185) and 78.8% (2402/3048) in 1989 and 1998, respectively . The questionnaire was validated with specific immunoglobilin E (IgE) posi tivity as the reference in a random sample of responders in connection with both surveys. We found a significantly increased prevalence of subjects who reported shor tness of breath on exposure to pollens (6.6% vs. 10.3%, odds ratio 1.61. 95 % CI 1.34-1.95). furry animals (5.4%, vs. 7.6%. odds ratio 1.45, 95% CI 1.1 7-1.79), and house dust (7.8% vs. 10.2%, odds ratio 1.35, 95% CI 1.12-1.61) . The validation of these symptoms showed that the positive predictive valu es were reasonably stable over time. which may support that a true increase in allergic asthma has occurred. In conclusion, the prevalence of allergic asthma symptoms increased signifi cantly in this adult general population over a 9-year period. (C) 2001 HARC OURT PUBLISHERS LTD.