Prevalence and Trend of Allergen Sensitization in Adults and Children with Atopic Dermatitis Referred for Patch Testing, North American Contact Dermatitis Group Data, 2001-2016

BACKGROUND The association between atopic dermatitis (AD) and allergic contact dermatitis (ACD) is controversial. OBJECTIVES To analyze the prevalence, reaction strength, and trends of the most commonly positive and relevant allergens in patients with AD referred for patch testing. METHODS Retrospective analysis of 36,834 patients from the North American Contact Dermatitis Group 2001-2016. RESULTS Most adults (56.0%) and children (52.8%) with a history of AD had a final diagnosis of ACD. Adults (66.5% vs. 65.6%; Chi-square, P=0.1459) and children (61.4% vs. 62.3%, P=0.7074) with or without a history of AD had similar proportions of ≥1 allergic patch test reaction. Adults with a history of AD had a greater number of allergic patch test positive reactions than without (2.0±2.4 vs. 1.9±2.3; t-test, P<0.0001), while children did not (1.5±1.8 vs 1.4±1.6, P=0.3839). Nickel sulfate, methylisothiazolinone, formaldehyde, fragrance mix I, sodium gold thiosulfate, and thimerosal were the most common allergens in adults and children with a history of AD. In multivariable logistic regression models, adults with vs. without a history of AD had increased odds of reacting to 10 of the top 25 NACDG screening allergens. Most allergens had similar strengths of reaction in adults or children with and without a history or current AD diagnosis, with cobalt, fragrance mix I, and propylene glycol having weaker reactions. In multivariable logistic regression, adults with vs. without AD history had increased odds of relevance for 10 of the 25 most currently relevant allergens, whereas children with AD history did not have increased relevance for any specific allergens. CONCLUSION Most patients referred for patch testing with AD history had a final diagnosis of ACD. Patients with AD history had similar likelihood of having a positive patch test reaction as those without AD history. Adults with AD history had a higher number of positive patch test reactions.