1. The prevalence of allergic diseases and the overall pattern of sensitization among 14-15 years old adolescents in two Danish birth cohorts 14 years apart Christiansen ES¹, ², Kjaer HF², Eller E¹, Bindslev-Jensen C¹, Høst A², Andersen KE¹ Mørtz CG¹, Halken S² 1. Department of Dermatology and Allergy Center, Odense University Hospital, University of Southern Denmark, DK-5000 Odense C, Denmark 2. Hans Christian Andersen Children’s Hospital, Odense University Hospital, University of Southern Denmark, DK-5000 Odense C, Denmark Background The prevalence of allergic diseases has increased during the second half of the 20 th century. Though, the prevalence of asthma seems to have reached a plateau in some countries, while this may not be the case for other allergic diseases Prospectively we investigated two unselected birth cohorts from Odense, Denmark 14 years apart: Odense85 cohort and DARC98/99 (Danish Allergy Research Center) cohort Using data from these two birth cohorts we compared the 12 month period prevalence of allergic diseases and sensitization in adolescence (14-15 years) Methods The Odense85 cohort: A prospective non-intervention birth cohort comprising 276 infants born in 1985 Participants underwent physical examination by a doctor, interview and specific IgE testing at 1.5, 5, 10, 15 and 26 years The DARC98/99 cohort: A prospective non-intervention birth cohort comprising 562 children born in 1998/99 Participants underwent physical examination by a doctor, interview and specific IgE testing at 0, 3, 6,12, 18 months and 3, 6, 14 years In both cohorts the diagnostic criteria of asthma, eczema and rhinoconjunctivitis were predefined, generally accepted and in agreement with GINA, Hanifin- Rajka, ARIA Sensitization: Defined as specific IgE (sIgE) ≥ 0.35 kU/l (ImmunoCap, Themofischer, Sweden) Conclusion The 12 month period prevalence of rhinoconjunctivitis at the age of 14-15 years has significantly increased from 2000 to 2014 in Odense, Denmark while the overall prevalence and pattern of sensitization did not change Figure 1: The 12 month prevalence (with 95% CI) of asthma, eczema, rhinoconjunctivitis and any allergic diseases among 14-15 years old adolescents in the Odense85 and DARC98/99 cohorts Results Odense85 cohort: Examination at 15 years in 2000 Follow-up rate: 76% (215/276): sIgE analyzed in 74% (158/215) DARC98/99 cohort: Examination at 14 years in 2013-14 Follow-up rate: 66% (372/562): sIgE analyzed in 86% (320/372) Differences between the two cohorts 14 years apart: There were significantly higher prevalence of rhinoconjunctivitis in the DARC98/99 cohort (fig 1) No difference in the prevalence of asthma and eczema (fig 1) The overall prevalence and pattern of sensitization were the same in the two cohorts (table 1) Odense85 (15yrs) n=158 DARC98/99 (14yrs) n=320 P-value Overall sensitization: To at least one allegen 32% 0.87 Pollen (grass, birch, mugwort)18%23%0.19 Animals (dog, cat, horse)9%11%0.48 House dust mites (derm.farinae, derm. pteronyssinus) 18%17%0.75 Moulds (cladosporium, alternaria) 8%4%0.09 Foods (milk, egg)3%5%0.29 Table 1: Sensitization by specific sIgE≥0.35 kU/l to different allergens among 14-15 years old adolescents in the Odense85 and DARC98/99 cohorts References: Nissen SP, Kjaer HF, Host A, Nielsen J, Halken S. The natural course of sensitization and allergic diseases from childhood to adulthood. Pediatric allergy and immunology : 2013;24(6):549-55.