Background: Food allergy is an increasing health problem in children. Previous studies have reported conflicting results about the diagnostic value of atopy patch test (APT) in food allergies.
Objectives: To investigate the accuracy of APT in identifying non-IgE-mediated gastrointestinal food allergy to pasteurized cow's milk, heated cow's milk, white and yolk egg, soy, wheat, walnut, sesame, pistachio, almond, peanut, date and cumin which are popular food ingredients in Iran.
Methods: This study was performed on children with GI allergic problems who did not improve after at least 4 weeks of cow's milk protein elimination. Atopic patch test (APT) was performed and the elimination diet was considered according to APT results and after resolving symptoms, introduction of each accused food was done sequentially.
Results: 53 children under 7 years old with mean age of 19.6 months underwent APT and the results were verified by open oral food challenge. Sensitivity in the rage of 59%-95%, specifity of 80.7-92.8, positive predictive values of 75-96.4 and negative predictive value of 23-80.7% were calculated depending on the type of food. Compared to the heated raw cow's milk, the pasteurized/homogenized cow's milk reaction was significant.
Conclusion: APT can be included in the diagnostic workup of non-IgE-mediated GI allergy because it's safe and has great accuracy. However, several aspects require further investigation especially to enable the standardization of the technique. We should be aware of allegenicity of our foods due to processing and geographic region.