A 30-year Patch Testing Experience at Siriraj Dermatology

Abstract

Objective: To identify trends of contact allergy and patch testing amendments at the Contact Dermatitis Clinic, Department of Dermatology, Faculty of Medicine Siriraj Hospital, Mahidol University. Materials and Methods: Medical records of 6,862 patients referred to our clinic between January 1992 and December 2021 for patch testing were reviewed. Results: The number of patients patch tested increased and reached a peak of 600 patients/year in 2019 before the COVID-19 pandemic. The most frequently used series was baseline, while the most used specific series was cosmetics. The overall positivity rate was 69%. The highest positivity rate was in the cosmetics series (70.2%). Nickel sulfate was the most common contact allergen found (24.2%). Conclusion: Our patch test service has been growing in the last 30 years. The series of allergens used for patch testing has been amended every few years to be up-to-date with current global trends of contact allergies. Continual surveillance of contact prevalence and periodic updating of those series are necessary to enhance our ability to detect culprit contact allergens, which could help us improve care of our patients