What is the optimal duration for a ROAT ? The experience of the French Dermatology and Allergology group ( DAG )

BACKGROUND AND OBJECTIVES: The repeated open application test (ROAT) is an adjuvant investigation measure to patch testing in the diagnosis of allergic contact dermatitis. ESCD recommends a 15 days duration but its overall duration varies according to publications and patients hardly adhere to prolonged ROAT duration beyond 1 week. MATERIALS AND METHODS: The Dermatology and Allergy Group of the French Society of Dermatology performed a prospective study with the aim of determining the best duration for the ROAT. RESULTS: A total of 328 ROAT results were collected for topical products, including cosmetics (60%) and topical medications (31.1%). Fifty-nine (18%) ROATs were positive, and 16 (5%) were doubtful. All the positive ROATs occurred within 10 days, with a median time to positivity of 3 days. CONCLUSION: According to our results, a minimum duration of 10 days is necessary to achieve a positive ROAT to a topical product.