title: Diagnostic accuracy of atopy patch tests for food allergy in children with atopic dermatitis aged less than two years.
abstract: BACKGROUND
  Atopy patch tests (APT) have been introduced as a valuable tool for the diagnosis of food allergy. However, interpretation of the readout of APT requires further clarification.
  
  
  OBJECTIVE
  To investigate the accuracy of APT in identifying atopic sensitisation to hen's eggs (HE), cow's milk (CM), soybean and wheat in Chinese children with atopic dermatitis (AD) aged less than two years and to evaluate skin signs of APT for accurate diagnosis of food allergy.
  
  
  METHODS
  APT was performed and food allergy confirmed by open oral food challenges with HE, CM, soybean and wheat in 150 Chinese AD children aged less than two years. The sensitivity, specificity, positive (PPV) and negative (NPV) predictive values, positive (LR+) and negative likelihood ratio (LR-) of APT were calculated.
  
  
  RESULTS
  Erythema and infiltration were not sufficiently indicative of a positive APT. The PPV increased with the appearance of indurations and the number of papules. The true positive APT rate increased from scores of + to +++. The PPV and specificity were 100% while APT scores of +++ were obtained with HE, CM and wheat. The sensitivity of APT with HE, CM, soybean and wheat allergy ranged from 59.6% to 90.5%, while the specificity ranged from 82.1% to 92.4%.
  
  
  CONCLUSIONS
  The APT is a suitable method for the diagnosis of AD in Chinese children aged less than two years with food allergies. Erythema and infiltration are not sufficient indicators of APT positivity. The PPV increases with indurations and the number of papules.
authors.affiliation: Department of Dermatology, Children's Hospital of Chongqing Medical University, Chongqing 400014, China.
authors.forename: H
authors.initials: H
authors.lastname: Yang
authors.affiliation: Department of Dermatology, Children's Hospital of Chongqing Medical University, Chongqing 400014, China.
authors.forename: Y Z
authors.initials: YZ
authors.lastname: Xiao
authors.affiliation: Department of Dermatology, Children's Hospital of Chongqing Medical University, Chongqing 400014, China.
authors.forename: X Y
authors.initials: XY
authors.lastname: Luo
authors.affiliation: Department of Dermatology, Children's Hospital of Chongqing Medical University, Chongqing 400014, China.
authors.forename: Q
authors.initials: Q
authors.lastname: Tan
authors.affiliation: Department of Dermatology, Children's Hospital of Chongqing Medical University, Chongqing 400014, China. Electronic address: huawpfk@163.com.
authors.forename: H
authors.initials: H
authors.lastname: Wang
mesh_terms: D000367:Age Factors; D000485:Allergens / Q000276:immunology; D000818:Animals; D002417:Cattle; D002681:China; D003876:Dermatitis, Atopic / Q000150:complications / Q000175:diagnosis* / Q000276:immunology; D005260:Female; D005512:Food Hypersensitivity / Q000150:complications / Q000175:diagnosis* / Q000276:immunology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008892:Milk / Q000276:immunology; D010063:Ovum / Q000276:immunology; D010328:Patch Tests; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D013025:Glycine max / Q000276:immunology; D014908:Triticum / Q000276:immunology
chemical_list: D000485:Allergens