BACKGROUND: There is evidence that the prevalence of respiratory allergy has increased in children in many countries. However, this evidence is largely based on questionnaire data, and little is known about similar trends in adults. We investigated whether the prevalence of specific IgE to aeroallergens had increased in an adult general population over an 8-year period.

MATERIAL AND METHODS: Two cross-sectional surveys were carried out in 1990 and 1998. A screening questionnaire on respiratory symptoms sent to random samples of 15-41-year-old subjects living in Copenhagen (Denmark) preceded both surveys. Random samples of responders were invited to a health examination, which included assessment of specific IgE to six common aeroallergens. Totals of 312 (74.6% of those invited) and 482 (53.4% of those invited) subjects were examined in 1990 and 1998, respectively. Serum samples from both surveys were analysed in 1999.

RESULTS: The prevalence of specific IgE to at least one allergen increased significantly from 1990 to 1998 (26.5% versus 33.9%; odds ratio adjusted for sex, age, and season of examination, 1.63; 95% confidence interval, 1.15-2.32). This increase remained unexplained after adjustment for changes in questionnaire variables on life-style and home environment. The clinical significance of this increase was underlined by a corresponding increase in the prevalence of allergic rhinitis symptoms associated with specific IgE positivity.

DISCUSSION: We found that the prevalence of specific IgE positivity to aeroallergens increased in an adult Danish general population from 1990 and 1998.