Contact sensitization to common haptens is associated with atopic dermatitis: new insight

Abstract

It has been much debated whether atopic dermatitis (AD) is associated with contact sensitization as past findings have been conflicting. A positive association might change our clinical practice. To investigate the association between AD and contact sensitization taking the likely route of allergen exposure into account. Questionnaire and clinical data from a cross-sectional study performed in a general population in Copenhagen. In total, 3202 adults aged 18-69 years were patch tested, filaggrin genotyped for 2282del4 and R501X and questioned about AD. The variable 'contact sensitization to at least one allergen, but not nickel and thimerosal' was significantly associated with AD (odds ratio 2·53, 95% confidence interval 1·59-4·04). The higher prevalence of contact sensitization was driven mainly by fragrance chemicals. In a subanalysis in nonpierced women, a positive association was also found for nickel sensitization. Nickel and thimerosal sensitization may introduce bias in data analysis as these allergies often develop following skin piercing where the skin compartments are bypassed. We suspect that individuals with self-reported AD from this study mainly had mild disease. However, clinicians should be aware of increased levels of contact sensitization in individuals with AD. Patch testing should therefore be considered at an early point in individuals with a history of AD and active disease. The fundamental relationship between atopic disease and environmental chemical exposure may be of a more complex and intimate nature than previously supposed.