title: The component-specific to total IgE ratios do not improve peanut and hazelnut allergy diagnoses.
abstract: Specific IgE measurement predicts the outcome of oral food challenges with considerable uncertainty when evaluating food allergy.
  
  
  
  Our aim was to assess whether accounting for the ratio of component- or allergen-specific to total IgE can improve this prediction.
  
  
  
  This multicenter study collected blood samples from children with suspected peanut or hazelnut allergy referred to allergy specialist clinics for food challenges. Specific IgE to peanuts, hazelnuts, and their components (Ara h 1, Ara h 2, Ara h 3, Ara h 8, Cor a 1, Cor a 8, Cor a 9, and Cor a 14) and total IgE levels were determined by using the ImmunoCAP-FEIA. Specific to total IgE ratios were compared with raw IgE levels in terms of discrimination and prediction.
  
  
  
  Eighty-eight (43%) of 207 children with suspected peanut allergy and 44 (31%) of 142 children with suspected hazelnut allergy had symptoms during food challenge. Discrimination was similar for raw and ratio measures: areas under the curve of 0.93 for Ara h 2-specific IgE versus 0.92 for the Ara h 2-specific/total IgE ratio and 0.89 for Cor a 14-specific IgE versus 0.87 for the Cor a 14-specific/total IgE ratio. The probability for a positive peanut challenge with 0.35 kU/L Ara h 2-specific IgE was 16% when the total IgE level was greater than 500 kU/L compared with 51%/48% for low/medium total IgE levels (<100/100-500 kU/L). A positive hazelnut challenge with 0.35 kU/L Cor a 14-specific IgE was estimated in 7% when total IgE levels were high compared with 34%/32% with low/medium total IgE levels.
  
  
  
  Raw Ara h 2- and Cor a 14-specific IgE levels were the best single predictors for pediatric peanut and hazelnut allergies, suggesting the omission of challenges at very high levels. Calculating ratio measures did not improve prediction in this population. However, estimation of individual probabilities for challenge outcomes could be supported by total IgE levels because high levels might indicate lower probabilities at a given component-specific IgE level.
authors.affiliation: Charité - Universitätsmedizin Berlin, Institute for Social Medicine, Epidemiology and Health Economics, Berlin, Germany. Electronic address: linus.grabenhenrich@charite.de.
authors.forename: Linus
authors.initials: L
authors.lastname: Grabenhenrich
authors.affiliation: St Marien-Hospital, Department for Pediatrics, Bonn, Germany.
authors.forename: Lars
authors.initials: L
authors.lastname: Lange
authors.affiliation: Charité - Universitätsmedizin Berlin, Department of Pediatric Pneumology and Immunology, Berlin, Germany.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Härtl
authors.affiliation: Charité - Universitätsmedizin Berlin, Department of Pediatric Pneumology and Immunology, Berlin, Germany.
authors.forename: Birgit
authors.initials: B
authors.lastname: Kalb
authors.affiliation: German Red Cross Hospital, Department for Pediatrics, Berlin, Germany.
authors.forename: Mandy
authors.initials: M
authors.lastname: Ziegert
authors.affiliation: St Marien-Hospital, Department for Pediatrics, Bonn, Germany.
authors.forename: Antje
authors.initials: A
authors.lastname: Finger
authors.affiliation: Children's Hospital, Wangen, Germany.
authors.forename: Neda
authors.initials: N
authors.lastname: Harandi
authors.affiliation: Children's Hospital, Wangen, Germany.
authors.forename: Ruppert
authors.initials: R
authors.lastname: Schlags
authors.affiliation: Marien-Hospital, Children's Department, Wesel, Germany.
authors.forename: Monika
authors.initials: M
authors.lastname: Gappa
authors.affiliation: Marien-Hospital, Children's Department, Wesel, Germany.
authors.forename: Letizia
authors.initials: L
authors.lastname: Puzzo
authors.affiliation: Children's Hospital Lichtenberg, Berlin, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Stephan
authors.affiliation: Children's Hospital, Stuttgart, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Heigele
authors.affiliation: Children's Hospital Osnabrück, Department for Pediatrics, Osnabrück, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Büsing
authors.affiliation: Children's Hospital Auf der Bult, Hannover, Germany.
authors.forename: Hagen
authors.initials: H
authors.lastname: Ott
authors.affiliation: Charité - Universitätsmedizin Berlin, Department of Pediatric Pneumology and Immunology, Berlin, Germany; German Red Cross Hospital, Department for Pediatrics, Berlin, Germany.
authors.forename: Bodo
authors.initials: B
authors.lastname: Niggemann
authors.affiliation: Charité - Universitätsmedizin Berlin, Department of Pediatric Pneumology and Immunology, Berlin, Germany; Icahn School of Medicine at Mount Sinai, New York, NY.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Beyer
mesh_terms: D000485:Allergens / Q000008:administration & dosage / Q000276:immunology; D000918:Antibody Specificity / Q000276:immunology; D052179:Antigens, Plant / Q000276:immunology; D010367:Arachis / Q000009:adverse effects*; D019540:Area Under Curve; D002648:Child; D002675:Child, Preschool; D015897:Comorbidity; D031211:Corylus / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007114:Immunization; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology*; D007223:Infant; D008297:Male; D021184:Nut Hypersensitivity / Q000175:diagnosis* / Q000276:immunology*; D021183:Peanut Hypersensitivity / Q000175:diagnosis / Q000276:immunology; D012372:ROC Curve
chemical_list: D000485:Allergens; D052179:Antigens, Plant; D007073:Immunoglobulin E
keywords: Ara h 2 allergen; Cor a 14 allergen; Food hypersensitivity; IgE; hazelnut; peanut