The repeated open application test (ROAT).

Repeated open application tests (ROATs) were performed with common ingredients of vehicles in 86 patients with contact dermatitis. The substances were applied twice daily for 7 days to the flexor aspect of the forearm near the cubital fossa, unless dermatitis appeared earlier. Of the patients with a questionable (?+) patch test result, 44% were positive in ROATs. The corresponding figure was 80% in the patients with a positive (+ or ++) response in the patch test, when the results of ROAT with propylene glycol were excluded. Only 5 of 14 patients reacting to 30% or to 10% propylene glycol but not to 1% in water in patch testing, showed a positive result to a cream containing 5% propylene glycol in ROAT. All 5 patients with a positive patch test reaction to 1% propylene glycol reacted to 5% propylene glycol in ROAT. The results suggest that ROATs should be performed more often, especially in patients in whom little known or new allergens are suspected as being the cause of allergic contact dermatitis.