title: Diagnostic value of hazelnut allergy tests including rCor a 1 spiking in double-blind challenged children.
abstract: BACKGROUND
  The diagnostic value of hazelnut allergy tests in double-blind challenged children is largely unknown. The aim of this study was to analyze the performance of current diagnostic tests for hazelnut allergy in children and the effect of spiking.
  
  
  METHODS
  Data of 151 children who underwent a double-blind placebo-controlled food challenge for hazelnut were analyzed. The positive predictive value and negative predictive value (PPV/NPV) of level of specific IgE (sIgE) for hazelnut, the influence of rCor a 1 spiking of the ImmunoCAP, and size of the skin prick test (SPT) for hazelnut were determined, also in relation to the severity of the hazelnut allergy. Reported accidental ingestion leading to an allergic reaction to hazelnut was also analyzed in relation to hazelnut allergy.
  
  
  RESULTS
  Specific IgE ≥0.35 kU(A) /l for hazelnut was a moderate predictor for hazelnut allergy. The spiking decreased the PPV from 41% to 38% and increased the NPV from 91% to 100% for sIgE ≥0.35 kU(A) /l. The maximum reached PPV was 73% for sIgE cutoff of 26 kU(A) /l. Level of sIgE before spiking was significantly different between different grades of severity and was lost after spiking. Skin prick test was a better predictor for hazelnut allergy and severity than the level of sIgE. A history of accidental ingestion leading to an allergic reaction to hazelnut had a predictive value of 59% for hazelnut allergy.
  
  
  CONCLUSIONS
  This study showed a good NPV of diagnostic tests for hazelnut allergy in children which further improved by rCor a 1 spiking. However, the PPVs are moderate and decreased by spiking.
authors.affiliation: Department of Dermatology and Allergology, University Medical Center Utrecht, Utrecht, the Netherlands. l.j.n.masthoff@umcutrecht.nl
authors.forename: L J
authors.initials: LJ
authors.lastname: Masthoff
authors.forename: S G
authors.initials: SG
authors.lastname: Pasmans
authors.forename: E
authors.initials: E
authors.lastname: van Hoffen
authors.forename: M J
authors.initials: MJ
authors.lastname: Knol
authors.forename: C A
authors.initials: CA
authors.lastname: Bruijnzeel-Koomen
authors.forename: A E
authors.initials: AE
authors.lastname: Flinterman
authors.forename: P
authors.initials: P
authors.lastname: Kentie
authors.forename: A C
authors.initials: AC
authors.lastname: Knulst
authors.forename: Y
authors.initials: Y
authors.lastname: Meijer
mesh_terms: D019540:Area Under Curve; D002648:Child; D002675:Child, Preschool; D031211:Corylus / Q000009:adverse effects / Q000276:immunology*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D008297:Male; D021184:Nut Hypersensitivity / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D010940:Plant Proteins / Q000276:immunology*; D011237:Predictive Value of Tests; D012372:ROC Curve; D012882:Skin Tests
chemical_list: C061277:Cor a I protein, hazel; D010940:Plant Proteins; D007073:Immunoglobulin E