An audit to identify the optimum referral rate to a contact dermatitis investigation unit

The principle of patch testing is to identify individuals with a contact allergy of relevance to their disorder and to provide avoidance advice in an attempt to improve or resolve their condition. We aimed to define an optimum referral rate to a centralized contact dermatitis unit using a retrospective analysis of data relating to 10 consultants. The results showed no significant difference (P = 0.21) in the percentage of relevant positive individuals identified between the consultants. However, a linear relationship (r = 0.99) was seen between the number of relevant positive allergic reactions and the number referred by individual consultants. We propose that the minimal annual referral rate for patch testing from a predominately urban population in a developed country is one in 700 of the population.