Role of atopy patch test for diagnosis of food allergy-related gastrointestinal symptoms in children

Background Double‐blind, placebo‐controlled food challenge is the gold standard for diagnosing food allergy. However, it is a time‐consuming procedure and requires onsite medical supervision and resuscitating medicines and devices on hand. The objective of this study was to compare the atopy patch test (APT) with the oral food challenge test (OFC) in children with suspected food allergy‐related gastrointestinal (GI) symptoms. Methods A prospective self‐controlled study enrolled children with a history of suspected food allergy‐related GI symptoms. Skin prick test (SPT) and APT using lyophilized and commercial allergen extracts for cow's milk, egg, wheat, soy, and shrimp were evaluated, and OFC was performed. Results Thirty‐nine patients (25 boys, median age 2.4 yrs) with 76 events of suspected food allergy‐related GI symptoms were enrolled. SPT was positive in 11/76 events (14.5%). Sensitivity, specificity, predictive values, and likelihood ratio were calculated related to the food challenge outcome. Of 41 OFC, 30 (73.2%) were positive. APT using lyophilized allergen extracts yielded high sensitivity (80%) and high positive predictive value (85.7%). APT using commercial allergen extracts yielded low sensitivity (30%) but high specificity (90%). The negative predictive value of APT using lyophilized and commercial allergen extracts was 53.8% and 32.2%, respectively. All cases with positive APT using lyophilized allergen extracts together with positive SPT also had positive OFC. Conclusion In contrast to commercial extracts, APT with lyophilized allergen extracts is reliable, safe, and maybe useful for the diagnosis of suspected food allergy‐related GI symptoms in children. OFC is still needed in most of the cases.