Background Food allergy is a common problem in patients with atopic dermatitis (AD), particularly in children. While immediate reactions to food are well characterized, the importance of food as a provocation factor for late eczematous reactions has been a subject of debate for several decades.
Objective To investigate the importance of food for the induction of late eczematous reactions in children with AD and to correlate the clinical outcome to the results of specific IgE determinations and atopy patch tests (APTs).
Methods One hundred and six double-blind placebo-controlled food challenges (DBPCFCs) to cow's milk, hen's egg, wheat and soy in 64 children with AD (median age 2 years) were analysed retrospectively. Total and food-specific IgE were determined by CAP RAST FEIA and APTs with native foodstuff were performed. The diagnostic values of specific IgE and APT results were calculated.
Results Forty-nine (46%) of the challenges were related to a clinical reaction. An exacerbation of AD (late eczematous reaction) commonly occurred 24 h after the ingestion of food. Isolated late eczematous reactions were seen in 12% of all positive challenges. Forty-five percent of the positive challenges were associated with late eczematous responses, which followed immediate-type reactions. The sensitivity of food-specific IgE and the APT was 76% and 70%, respectively. Specific IgE and APT were often false positive, which resulted in low positive predictive values (64% and 45%, respectively).
Conclusions Late eczematous reactions may often be observed upon food challenge in children with AD. Due to the poor reliability of food-specific IgE and APT results DBPCFCs have still to be regarded as the gold standard for the appropriate diagnosis of food responsive eczema in children with AD.