The prevalence of allergy and IgE antibodies to inhalant allergens in Swedish school children.

Out of 242 children (10 and 14 years of age) in one school-district 221 (93%) were evaluated for atopy/allergy by a questionnaire, interview, physical examination and determination of S-IgE and IgE-antibodies (RAST) to pollen, animal danders and house dust mite. Eighteen months after the initial examination all 221 children were re-interviewed. All children with previous or current symptoms of atopy/allergy, all children with positive RAST despite a negative history and 20 non-atopic/non-allergic RAST-negative children were tested with a skin prick test (SPT). At the initial examination the cumulative incidence of atopy/allergy was 32.6% and positive RAST was obtained in 40 children (18.1%). At the follow-up the incidence of atopic/allergic symptoms during the last 18 months was 25.8%. The current prevalence of allergy to pollen and danders, assessed by interview only, was 19% and 9% respectively while determined by both interview and positive SPT 15% and 5% respectively. The mean S-IgE (78 kU/l) of the children with current symptoms differed significantly (p less than 0.001) from that (19 kU/l) of the non-atopic ones. There was no relationship between S-IgE and the stage of puberty. Ten of the 11 children with positive RAST, but no atopy/allergy initially, developed clinical atopy/allergy during the follow-up.