Evaluation of drug patch tests in children

Background: Patch tests are used to diagnose nonimmediate T-cell-mediated drug hypersensitivity reactions. The aim of this study was to evaluate the results of patch tests performed with suspect drugs in children. Methods: Patients < 18 years of age who had a drug patch test at the pediatric allergy outpatient clinic of our hospital between January 2014 and January 2020 were included in the study. Age, sex, culprit drug(s), reaction characteristics, and patch test results were recorded from the patients' files. Results: A total of 105 drug patch tests were performed on 71 patients during the study period. The patients' median age was 7 years (interquartile range, 4-11 years), and 57.7% (n = 41) were boys. Twenty-three patients (32.3%) had severe cutaneous adverse reaction (Stevens-Johnson syndrome in 11, drug reaction with eosinophilia and systemic symptoms in 9, and acute generalized exanthematous pustulosis in 3 patients), 45 (63.3%) had maculopapular rashes, and 3 (4.2%) had fixed drug eruption. A total of 20 patch test results (28%) were positive: 18 of 44 patch tests (40.9%) with antiepileptic drugs and 2 of 48 patch tests (4.1%) with antibiotics. Positive results were obtained in 23% of the patch tests (6/26) in 20 patients with severe cutaneous adverse reactions and in 17.7% of the patch tests (14/79) in 51 patients with mild cutaneous reactions. No adverse reactions occurred during or after the patch tests. Conclusion: In our study, patch test positivity was more common with antiepileptic drugs and in patients with severe cutaneous drug reaction.