Atopy Patch Test For The Diagnosis Of Food Allergy In Children

Background:The gold standard for diagnosing food allergy is double-blind,placebo-controlled food challenge(DBPCFC).However,DBPCFC is time-consuming,resource-intensive and requires onsite medical supervision and resuscitating medicines and devices on hand.It may even induce anaphylaxis;hence,there is a need to try and find safer and cheaper alternatives.The diagnostic accuracy of atopy patch test(APT)for food allergy in children remains largely undefined.Methods:From October 2015 to December 2017,we enrolled children aged 1 month to 18 years old referred to the Department of Gastroenterology in Children’s Hospital of Chongqing Medical University because of suspected food allergy-related gastrointestinal symptoms.Atopy patch test using fresh allergen extracts for cow’s milk,egg and soy was conducted and open food challenge(OFC)was performed.Sensitivity,specificity,positive predictive value(PPV),negative predictive value(NPV)and likelihood ratio were calculated according to the OFC outcome.Results:This prospective cohort study includes 107 patients(43 girls,64 boys)aged 2 to 19 months.Of 142 OFC,82(57.7%)were positive.The overall APT diagnostic accuracy was sensitivity of 70.7%,specificity of 91.7%,PPV of 92.1%,NPV of 69.6%.The results of APT for specific food allergy were(1)cow’s milk allergy:sensitivity 80.4%,specificity 91.3%,PPV 95.7%,NPV 65.6%;(2)egg allergy:sensitivity 52.4%,specificity 93.5%,PPV 84.6%,NPV 74.4%;(3)soy allergy:sensitivity 40.0%,specificity 83.3%,PPV 66.7%,NPV 62.5%.Conclusion:Atopy patch test is a reliable,safe and useful tool for the diagnosis of food allergy in children with gastrointestinal symptoms.However,the sensitivity of APT is low and therefore excluding food allergy should be verified by food challenge test.