Epidemiology of Atopy Patch Tests With Food and Inhalant Allergens in an Unselected Population of Children

Abstract

Ronchetti R, Jesenak M, Trubacova D, Pohanka V, Villa MP. Pediatr Allergy Immunol. 2008;19(7):599–604PURPOSE OF THE STUDY. The atopy patch test (APT) has been used as a diagnostic tool for patients with suspected food or inhalant allergy. The authors of this study assessed the prevalence of positive APT results with food or inhalant allergens in an unselected population of schoolchildren. The authors also evaluated the link between positive APT reactions and skin-prick tests (SPTs) for food and inhalant allergens, circulating eosinophils, and histamine skin reactivity.STUDY POPULATION. The study included an unselected population of 380 children 9 or 13 years of age living in Rome, Italy.METHODS. APTs were carried out with food (native or standardized) and inhalant allergens. All children also underwent SPTs with 5 common inhalant and 4 food allergens.RESULTS. The prevalence of positive APT reactions for foods in unselected children ranged between 4% and 11% for hen's egg, tomato, and wheat flour and was similar for the 2 age groups studied. The prevalence of positive APT reactions for milk was significantly lower in children of age 13 than in children of age 9 (P = .013). No concordance emerged between positive APT and SPT results for foods. Conversely, APT and SPT results for inhalant allergens yielded statistically significant concordance (P < .001).CONCLUSIONS. The APT produces positive reactions for food or inhalant allergens in a significant number of subjects in the general population of schoolchildren. Inhalant allergens probably induce a positive APT reaction through an immunoglobulin E–linked process, whereas food allergens probably do not.REVIEWER COMMENTS. The APT has been investigated as a new diagnostic tool for patients with food or inhalant allergies when non–immunoglobulin E–mediated reactions are considered, such as in identifying triggers for atopic dermatitis, allergic eosinophilic esophagitis, and food protein-induced enterocolitis syndrome. However, studies have demonstrated conflicting results for the utility of this test. Here, the authors investigated the prevalence of positive results of APT in an unselected population of schoolchildren and found that APTs produced positive reactions for foods in 4% to 11% of cases and for inhalant allergens in 4% to 30%, depending on the allergen used. This is important information to consider when investigating the APT as a potential diagnostic tool.