The first Australian Baseline Series: Recommendations for patch testing in suspected contact dermatitis

Background and objectives: Patch testing is a standard diagnostic tool used in the identification of causative allergens in allergic contact dermatitis. Ongoing surveillance of rates of allergen positivity is vitally important to detect trends and allow comparisons between countries. The objective of this study was to propose the first evidence-based Australian baseline series, based on retrospective review of our patch test data. We aimed to identify the most important and most relevant allergens in our population.

Methods: We conducted a 10-year (2001-2010) retrospective review of data from the contact dermatitis clinic and the occupational dermatitis clinic from our institution.

Results: We patch tested 5281 patients in all. The top 20 allergens with the highest number of relevant positive patch test reactions were: fragrance mix 1: nickel, potassium dichromate, Myroxylon pereirae, formaldehyde, p-phenylenediamine (PPD), thiuram mix, colophony (rosin), dermatophagoides mix, ammonium persulfate, quaternium-15, cobalt chloride, methylchloroisothiazolinone or methylisothiazolinone, diazolidinylurea, epoxy resin, 1,3-dimethylol-5,5-dimethyl hydantoin, Compositae mix, toluenesulfonamide formaldehyde resin, basic red 46 and imidazolidinyl urea.

Conclusion: We have elucidated the most frequent and relevant contact allergens in our patient population and used this information to construct the first Australian baseline series.