Prevalence of atopy and respiratory allergic diseases in the elderly SAPALDIA population

Background: Because of changing world demographics, the elderly population is steadily increasing. Few studies have assessed the prevalence of atopy and allergic diseases in elderly persons with objective measures. The aim of this paper is to describe the prevalence of atopy, self-reported allergic rhinitis and doctor's diagnosed asthma in persons over the age of 60 in Switzerland.

Methods: The cross-sectional examination of the Swiss Study on Air Pollution and Health in Adults (SAPALDIA 1), performed in 1991, included 9,651 adults aged 18-60 years. In 2001-2002 the same subjects were invited for a follow-up examination (SAPALDIA 2). Serum samples collected at baseline and follow-up were tested for specific IgE sensitization with the Phadiatop® (Phadia, Uppsala, Sweden, now Thermo Fisher Scientific) assay containing a mixture of common respiratory allergens (grass, birch, mugwort, Parietaria and olive pollen, dog, cat, horse, Cladosporium herbarum, house dust mite and flour mite). Atopy was defined as a positive result in the Phadiatop test according to guidelines by the manufacturer. The prevalence rates of atopy, self-reported allergic rhinitis and doctor's diagnosed asthma were evaluated by sex and age group (≤60 or >60 years).

Results: 7,667 subjects (men = 3,692/women = 3,975) participated in the follow-up by responding to a detailed questionnaire (80% of SAPALDIA 1 participants). Phadiatop results were available for 5,835 participants (men = 2,839/women = 2,996). Prevalence rates of atopy (Phadiatop positive) were 36.4% in men aged ≤60 years versus 26.2% in men aged >60 years and 30.6 and 18.1% in women, respectively (both p < 0.001). Prevalence rates of self-reported allergic rhinitis in subjects >60 years old were 13.0% for men and 15.4% for women (p = 0.12), and for doctor's diagnosed asthma 6.6% versus 7.6%, respectively (p = 0.40). Both rhinitis and asthma prevalences were higher in persons <60 years. The results were not sensitive to potential bias from nonparticipation at follow-up as demonstrated by imputation of sex- and age-specific allergic rhinitis and asthma among nonparticipants.

Conclusions: According to our estimates, the prevalence of allergic rhinitis among persons aged between 60 and 70 years in Switzerland in the present cohort is of the order of 13-15% and should not be underestimated, although it is lower than in age groups ≤60 years.