Background and objective: Little is known about late phase clinical reactions during oral food challenges and the value of specific IgE in terms of sensitivity and specificity.
Methods: We therefore analysed retrospectively the clinical outcome of 387 oral provocations during double-blind, placebo-controlled food challenge tests in 107 children with atopic dermatitis.
Results: Eighty-seven (81%) children showed a positive clinical reaction to at least one challenge. The vast majority of children (94%) showed clinical symptoms to one or two allergens. One hundred and thirty-one of 259 (51%) of verum challenges and 1/128 (0.8%) placebo challenge were assessed as positive. Oral provocations with hen's egg showed the highest percentage of positive reactions (70%). Sensitivity of specific IgE to the four allergens tested was 90%, specificity 30%. Sensitivity of the parental history as a predictive factor was 48%, specificity 72%. Ninety-two of 131 (70%) children with positive verum provocations showed early reactions, 33 (25%) late and six (5%) combined early and late reactions. In 84/131 (64%) positive provocations one organ system was involved, while in 44 (34%) provocations two and in three (2%) challenges three organ systems were involved. Skin reactions were the most frequent clinical manifestation leading to positive reactions followed by gastro-intestinal and respiratory symptoms. There was no correlation between titration dose and specific IgE. The subgroup of non-sensitized children did not differ in terms of sex, age or titration dose from the total study population.
Conclusion: Double-blind, placebo-controlled oral food challenges are helpful in distinguishing children with clinically manifested symptoms from those with food sensitization. Accurately identifying children with a clinical relevant food allergy may help to prescribe specific diets on a scientific basis, avoiding dietary limitations which may be unnecessary or even harmful.