Immediate- and delayed-type contact hypersensitivity in children older than 5 years with atopic dermatitis: a pilot study comparing different tests.

We conducted a prospective open study of immediate- and delayed-type contact hypersensitivity to food and other allergens in 33 children with atopic dermatitis (AD). The design of the study was exploratory and not randomized. Various methods for detecting immediate-type hypersensitivity were compared. Thirty-three children age 5 to 15 years with persistent AD were initially enrolled, but 3 dropped out. Nine patients had positive reactions to foods in the patch-scratch test, four had positive reactions in the skin application food test, and five had positive reactions to foods in the prick tests. Positive reactions to foods were observed in only three patients on the delayed-type patch tests. In all tests, but especially the patch-scratch and prick tests, positive reactions to food allergens were observed without clinically related symptoms. None of these tests gave ideal results. Twenty (67%) of the 30 children had positive reactions to inhalants in prick testing. Fourteen showed positive patch-test reactions with the European standard series (True Test). The most positive reactions were to nickel (9 patients), cobalt, and balsam of Peru. Restrictive measures led to evident improvement of AD only in some children. The results of this study illustrate that food allergy plays only a limited role in patients with AD age 5 to 15 years. We could not conclude which of the tests would predict which children might benefit from dietary manipulation.