The atopy patch test in the diagnostic workup of suspected food-related symptoms in children.

BACKGROUND: There is an increasing need to develop test instruments that make oral food challenges superfluous.

OBJECTIVE: We sought to study the utility of atopy patch tests (APTs) in the diagnostic workup of food allergy.

METHODS: We investigated 437 children (median age, 13 months; 90% with atopic dermatitis) referred for evaluation of suspected food allergy. Specific serum IgE (sIgE) measurements, skin prick tests (SPTs), APTs, and controlled oral food challenges were performed.

RESULTS: We analyzed 873 oral challenges with cow's milk, hen's egg, wheat, and/or soy. One thousand seven hundred single APTs were performed. As a single parameter, the APTs showed the best specificity compared with sIgE measurements, SPTs, or both. Combining the APT with either the SPT or sIgE measurement resulted in improved sensitivity and specificity. Decision points for sIgE measurement and for the SPT showed lower values when combined with a positive APT result. Correctly bypassing an oral food challenge with combined testing, including APTs, only between 0.5% and 7% (99% predicted probability) and between 6% and 14% (using 95% predicted probability) of children would fulfill the criteria for avoiding an oral food challenge.

CONCLUSION: Although the predictive capacity of the APT is improved when combined with sIgE measurement or the SPT, oral food challenges become superfluous in only 0.5% to 14% of study patients. In addition, the APT is time consuming and demands a highly experienced test evaluator.

CLINICAL IMPLICATIONS: For daily clinical practice, the APT adds only a small predictive value to the standard SPT and sIgE measurement in the diagnostic workup of suspected food-related symptoms in our study population.