Expanded Series and Personalized Patch Tests for Children: A Retrospective Cohort Study

Background Epicutaneous patch testing was developed as a simple and effective method for diagnosing allergic contact dermatitis (ACD). Despite its proven value in ACD diagnoses, there is no defined standard for patch testing in children. Objective The aims of this study were to assess patch test positivity in pediatric patients with and without a history of atopic dermatitis suspected to have ACD, to compare these results with what the Thin-Layer Rapid Use Epicutaneous (T.R.U.E.) Test would have captured, and to evaluate likely exposures. Methods Pediatric patients receiving a North American 80 Comprehensive Series patch test or a personalized patch test were analyzed for allergen sensitization 48 to 72 hours after patch removal. These data were analyzed for allergen inclusion in the North American 80 Comprehensive Series patch test compared with the T.R.U.E. Test, as well as compared with patients with and without a history of atopic dermatitis. Results Of the 29 patients (mean ± SD age = 10.9 ± 5.1 years), 25 children demonstrated at least 1 positive reaction, with a total of 81 reactions overall. 40 (49.4%) of the reactions came from allergens outside of the T.R.U.E. Test, including cocamidopropyl betaine, which was frequent in patients with atopic dermatitis. Conclusions Expanded and personalized patch tests provide a more comprehensive allergen inventory than the traditional T.R.U.E. Test. Pediatric patients frequently have reactions to allergens not included in the T.R.U.E. Test, and these allergens are commonly found in household products. Cocamidopropyl betaine was a particularly relevant allergen in our population. Expanded series patch testing and appropriate counseling should be provided to pediatric patients with ACD.