Pediatric contact allergy: A comparative study with adults

Background Pediatric allergic contact dermatitis is increasing. The patch-test allergens included in pediatric baseline series vary globally. The worldwide prevalence of pediatric reactions to allergens needs clarification. Objectives Identify the prevalence, associated factors, and culprit allergens for contact allergy among patch-tested Thai children, and compare with those for adults. Methods Baseline-series patch-test results from 2010-2019 were collected for patients younger than 18 years of age. As a control group, sex-matched adult patients were randomly selected. The results and characteristics of the two groups were compared. Results The median age of 112 patch-tested pediatric patients was 16 (range 2-17) years. Of the children, 35.5% had at least one positive reaction, significantly less than the 56.6% for adults. The five most common pediatric allergens were nickel sulfate (12.1%), potassium dichromate (8.0%), methylisothiazolinone (7.1%), fragrance mix II (6.0%), and carba mix (5.4%). Although similar, the 10 most common allergens of the groups differed in order. Positive reactions to cosmetic allergens were significantly less frequent among the children. Many allergens remained entirely negative. Conclusions The prevalence of positive reactions was lower in children, varying by population and region. The top-10 pediatric and adult causative allergens were almost identical. We recommend using the same baseline patch-test series for children and adults in our region.