Family history and risk of atopic dermatitis in children up to 4 years

Background The aetiology of atopic dermatitis (AD) is presumably multi-factorial, with interactions between genetic and environmental factors. Objective To investigate the relation between atopic family history and development of AD up to 4 years. Methods Using annual questionnaires, we studied the cumulative incidence of AD in 0-4-year-olds in a prospective birth cohort of 4089. Atopic diseases in parents and siblings were recorded at birth. The occurrence of serum immunoglobulin E (IgE) antibodies to inhalant and food allergens was analysed in 2614 4-year-olds, and AD was divided into non-IgE-associated and IgE-associated. Results Of the children without atopic parents, 27.1% developed AD; of those with single or double parental atopic history, 37.9% and 50.0%, respectively, did so. The effects of parental history of eczema and of atopic respiratory disease (ARD) did not differ significantly, nor did those of maternal and paternal history. Parental history of ARD increased the risk significantly more for IgE-associated AD than for non-IgE-associated AD (odds ratio (OR) 2.0; 95% confidence interval (0) 1.5-2.8 vs. OR 1.3; 95% CI 1.0-1.8), whereas the two forms lacked major differences in the effect of parental eczema. A history of eczema in older siblings was a risk indicator for both forms of AD (OR 2.1; 95% CI 1.4-3.3 vs. OR 1.8; 95% CI 1.2-2.6). Conclusions We found no difference between the effects of maternal and paternal atopic history. Parental eczema was a risk factor for AD irrespective of its association with IgE, but parental history of ARD mainly increased the risk of IgE-associated AD.