Early-life sensitization to hen's egg predicts asthma and rhinoconjunctivitis at 14 years of age.

BACKGROUND: Sensitization to both inhalant and food allergens has been shown to be risk factors for development of asthma and rhinoconjunctivitis (RC). However, few studies have addressed the role of transient or persistent IgE sensitization to specific allergens in early life for later development of allergic diseases. The aim of this study was to explore the association between transient and persistent sensitization in early life and the development of asthma and RC at 6 and 14 years. METHODS: The Danish Allergy Research Center (DARC) cohort is a prospective non-interventional birth cohort study comprising 562 children. For the purpose of this study, we examined a subgroup of the original cohort with specific IgE measured at, at least 3 of 4 follow-ups between 3 and 18 months of age (n = 366). Multiple logistic regression models were used to investigate the association between transient and persistent early-life sensitization to groups of and to individual allergens and asthma and RC at 6 and 14 years compared to a reference group with no sensitization. RESULTS: Both transient early-life sensitization and persistent early-life sensitization to cow's milk or hen's egg proteins were associated with asthma (aOR 3.99[1.41-11.32] and 5.95[1.78-19.92]) and RC (aOR 2.94[1.19-7.28] and 6.18[1.86-20.53]) at 14 years, this association being driven mainly by sensitization to hen's egg. Transient early-life sensitization to house dust mite (HDM) had increased risk of asthma (aOR 3.80[1.17-12.41]) at 14 years. CONCLUSIONS: Early transient IgE sensitization and persistent IgE sensitization to hen's egg were associated with asthma and RC at 14 years. Furthermore, sensitization to HDM was associated with asthma at 14 years.

The prevalence of atopic diseases and the patterns of sensitization in adolescence.

BACKGROUND: Atopic diseases are among the most common chronic diseases in adolescents, and it is uncertain whether the prevalence of atopic diseases has reached a plateau or is still increasing. The use of the ISAAC (International Study of Asthma and Allergy in Childhood) questionnaire has provided comparable prevalence rates from many countries, whereas studies including clinical examinations and strict diagnostic criteria are scarce. We aimed to investigate the prevalence of atopic diseases, the pattern of sensitization, and comorbidities at 14 years in a prospective birth cohort. METHODS: The children were examined eight times from birth to 14 years. Visits included questionnaire-based interviews, clinical examination, skin prick test, and specific IgE. RESULTS: Follow-up rate at 14 years was 66.2%. The 12-month prevalence of any atopic disease was high (40.3%) mostly due to a high prevalence of rhinoconjunctivitis (32.8%), whereas the prevalence of asthma was 12.9% and of atopic dermatitis 8.1%. In children with at least one atopic disease, 60% were sensitized, while only 16% of those without atopic diseases were sensitized. The frequency of sensitization depended on the phenotype. Among children with rhinoconjunctivitis only, rhinoconjunctivitis with concomitant asthma or atopic dermatitis or both 62.5%, 81.5%, 70%, and 100%, respectively, were sensitized, whereas it was 7.7% and 33.3% of children with only asthma or atopic dermatitis. CONCLUSION: The prevalence of rhinoconjunctivitis was high in adolescence. Children with rhinoconjunctivitis with and without comorbidities were frequently sensitized. Children with asthma without concomitant allergic rhinoconjunctivitis were rarely sensitized.

Low patch test reactivity to nickel in unselected adolescents tested repeatedly with nickel in infancy.

BACKGROUND: It is questionable how repeated patch tests with nickel sulfate in infancy affect nickel patch test reactivity at a later age. METHODS: The Danish Allergy Research Center (DARC) cohort encompasses 562 infants invited to a clinical examination including patch tests with nickel sulfate six times during the first 36 months of life. At the follow-up investigation at 14 years of age (2013-2014), participants were offered re-patch tests with nickel sulfate. The Odense Adolescence Cohort Study TOACS cohort encompasses 1501 schoolchildren evaluated for the first time at 14 years of age (1995-1996) including clinical examination and nickel sulfate patch tests. The prevalence of nickel sensitization in the DARC cohort was compared to the prevalence in the TOACS cohort at 14 years of age. RESULTS: Nickel sulfate sensitization was found in 1.2% of the participants from the DARC cohort tested repeatedly with nickel sulfate in early childhood and retested at 14 years of age compared to 8.6% of the participants from the TOACS cohort patch-tested for the first time at 14 years of age using the same patch test system and test concentration. CONCLUSION: The significant difference in nickel patch test reactivity comparing the two cohorts may reflect an immunologic effect or the effect of nickel regulation.

Early childhood risk factors for rhinoconjunctivitis in adolescence: a prospective birth cohort study.

BACKGROUND: Rhinoconjunctivitis is a global health problem and one of the most common chronic conditions in children. Development of rhinoconjunctivitis depends on both genetic and environmental factors. Many studies have investigated rhinoconjunctivitis, but only few studies have evaluated the risk factors for non-allergic rhinoconjunctivitis in children finding family history of atopic diseases and gender to be of importance. The aim of this study was to investigate possible risk factors in early life for rhinoconjunctivitis, allergic as well as non-allergic, in adolescence. METHODS: The children in the Danish Allergy Research Center cohort were examined eight times from birth to 14 years of age. Visits included questionnaire-based interview, clinical examination, skin prick test and specific IgE. We used univariate and multivariate logistic regression to investigate the relationship between early-life risk factors and the development of rhinoconjunctivitis, allergic as well as non-allergic, in adolescence. RESULTS: Follow-up rate at 14-years was 66.2%. The prevalence of rhinoconjunctivitis was 32.8%. Family history of atopic diseases (aOR 2.25), atopic dermatitis (aOR 3.24), food allergy (aOR 3.89), early sensitization to inhalant and food allergens (aOR 2.92 and aOR 3.13) and male gender (aOR 1.90) were associated with allergic rhinoconjunctivitis but not with non-allergic rhinoconjunctivitis. Early environmental tobacco exposure was inversely associated with rhinoconjunctivitis (aOR 0.42), allergic (aOR 0.47) as well as non-allergic (aOR 0.43). CONCLUSION: Different patterns of associations were revealed when stratifying rhinoconjunctivitis in allergic and non-allergic suggesting that allergic rhinoconjunctivitis and non-allergic-rhinoconjunctivitis are different phenotypes.