Background There is increasing consensus about the significance of food allergens in the pathogenesis of atopic dermatitis (AD) in infancy and childhood, with cow's milk and egg accounting for most of the reactions. Previous studies have indicated that multiple food sensitization, such as cereals, is very common in patients with cow's milk allergy (CMA). Evidence is lacking, however, as to its clinical relevance.
Objective The purpose of this study was to determine the concurrent occurrence of cereal allergy among children with challenge-proven CMA who have residual symptoms, such as AD and/or gastrointestinal symptoms, during cow's milk elimination diet. Further, we sought to evaluate the utility of patch testing in prescreening foods other than cow's milk behind allergic symptoms in children.
Methods The study population comprised 90 children, aged from 2.5 to 36 months (mean 1.1 years), with challenge-proven CMA. As a result of residual symptoms during meticulous cow's milk elimination diet (AD: n=80, and gastrointestinal: n=10), the children were put on a cereal elimination diet (oats, wheat, rye, and barley) and skin prick tests (SPT) and patch testing with cereals were performed. Open cereal challenge was performed to confirm cereal allergy.
Results Cereal challenge was positive in 66 (73%) of the children with CMA. Of them, 17% reacted with immediate reactions and delayed-onset reactions were seen in 83% of the children. SPT was positive in 23%, patch test in 67%, and either SPT or patch test was positive in 73% of the children with cereal allergy. SPT gave the best positive predictive value, whereas SPT together with patch test gave the best negative predictive value.
Conclusions Residual symptoms, such as eczema or gastrointestinal symptoms in CMA children may be a sign of undetected allergy to other food antigens. SPT with cereals aids in diagnosing cereal allergy in small children, especially when used together with patch testing.