Perfil das respostas aos testes de contato em crianças e adolescentes: estudo na Clínica Dermatológica da Santa Casa de Belo Horizonte

Abstract

Introduction: The patch-test is used for the identification of the allergen responsible for allergic contact dermatitis (ACD). It intends to reproduce a delayed type of hypersensitivity reaction by inducing the second phase of ACD (the efferent way). The knowledge about the frequency of allergens in children and adolescents may enable doctors to take preventive measures to avoid the development of ACD. There are few data about patch-test results in children and adolescents in Brazil. In Brazil there are two standardized patch-test series available: standard and cosmetics. Usually, all patients are patch tested with the standard series. When necessary, the cosmetic series is also tested. The use of this complementary cosmetic series increases cost and makes the technique more difficult in children. The objective of this study is to evaluate patch-test results in children and adolescents in a dermatology clinic in Brazil, identifying the most frequent allergens, comparing them in these two age groups and evaluating the need for the complementary cosmetic series use in those patients. Methods: This is a cross-sectional study to assess patch-test results of 125 children and adolescents with suspected allergic contact dermatitis from 1 to 19 years of age. Data from patch test results in children and adolescents in a dermatology clinic in Belo Horizonte, Minas Gerais Brazil, from 07/01/2003 to 06/30/2010 were collected and stored in the EpiInfo 3.5.1. Statistic program. Chi- square test was used for the analysis of the categorical variables and, when necessary, Fisher´s Exact Test was also employed. The significance level considered for all the analysis was 0.05. The materials used for the patch-tests were two series: Brazilian Standard Patch-Test Series and Brazilian Cosmetic Standard Patch-Test Series and aluminum chambers on adhesive tapes. Test readings were carried out at 48 and 96 hours. Only the 96 hour reading was considered for the statistical analysis. Results: Patch-test results were evaluated in 125 patients, 96 girls (76.8%) and 29 boys (23.2%). Age varied from 1 to 19 years, including 18 children, from 1 to 9 years and 107 adolescents from 10 to 19 years. Among the 125 tested patients, 74 had at least one positive reaction, the contact sensitization rate being 59.2% (74/125). Among 74 patients who had at least one positive reaction, 57 patients had present clinical relevance (57/74; 77.0%) to their positive tests. ACD diagnosis occurred in 45.6% of the tested patients. Tests were more frequently positive in adolescents (p=0.0014) than children and in females (p=0.0002) than in males. There was no significant statistical difference related to contact sensitization in patients with and without history of atopy. The substances from the Brazilian Standard Series that showed a higher sensitization frequency in children and adolescents (n=125) were as follows: nickel sulfate (n=46; 36.8%), thimerosal (n=23, 18.4%), neomycin (n=8; 6.4%), cobalt chloride and fragrance mix (n=5; 4.0% each), formaldehyde (n=4; 3.2%), potassium dichromate and ethylenediamine (n=3; 2.4% each). Children (n=18) had positive reactions only to nickel and fragrance mix. Among the substances tested with the Brazilian Cosmetic Series, for children and adolescents (n= 73), there was no positive reaction in children and only two substances had a positive reaction in adolescents: tosylamide formaldehyde resin (n=5; 6.8%) and chloroacetamide (n=1; 1.4%). There was a significant statistical difference (p=0.029) related to the sensitization to nickel (p=0.029) and thimerosal (p=0.042) between the two age groups. The head and the trunk were the body areas most affected by dermatitis most frequent in patients with positive tests. When the dermatitis initial affection occurred on the neck and trunk, the frequency of relevant positive tests was high. Conclusion: Nickel and fragrances were the only positive allergens (and relevant) in children. Nickel and tosylamide formaldehyde resin were the most frequent and relevant allergens among adolescents. Considering that there were only six positive reactions to the test with the Brazilian Cosmetics Series in the two age groups under study, and that, among these positive tests, 6.8% were to tosylamide formaldehyde resin, one can think of the utmost relevance of this substance, in relation to the other substances in this series, so as to evaluate the necessary screening for such patients.