title: Defining thresholds of specific IgE levels to grass pollen and birch pollen allergens improves clinical interpretation.
abstract: BACKGROUND
  Cut-off values and predictive values are used for the clinical interpretation of specific IgE antibody results. However, cut-off levels are not well defined, and predictive values are dependent on the prevalence of disease. The objective of this study was to document clinically relevant diagnostic accuracy of specific IgE for inhalant allergens (grass pollen and birch pollen) based on test result interval-specific likelihood ratios. Likelihood ratios are independent of the prevalence and allow to provide diagnostic accuracy information for test result intervals.
  
  
  METHODS
  In a prospective study we included consecutive adult patients presenting at an allergy clinic with complaints of rhinitis or rhinoconjunctivitis. The standard for diagnosis was a suggestive clinical history of grass or birch pollen allergy and a positive skin test. Specific IgE was determined with the ImmunoCAP Fluorescence Enzyme Immuno-Assay.
  
  
  RESULTS
  We established specific IgE test result interval related likelihood ratios for clinical allergy to inhalant allergens (grass pollen, rPhl p 1,5, birch pollen, rBet v 1). The likelihood ratios for allergy increased with increasing specific IgE antibody levels. The likelihood ratio was <0.03 for specific IgE <0.1 kU/L, between 0.1 and 1.4 for specific IgE between 0.1 kU/L and 0.35 kU/L, between 1.4 and 4.2 for specific IgE between 0.35 kU/L and 3.5 kU/L, >6.3 for specific IgE>0.7, and very high (∞) for specific IgE >3.5 kU/L.
  
  
  CONCLUSIONS
  Test result interval specific likelihood ratios provide a useful tool for the interpretation of specific IgE test results for inhalant allergens.
authors.affiliation: Laboratory Medicine, Immunology, University Hospitals, KU Leuven, Belgium.
authors.forename: Erna
authors.initials: E
authors.lastname: Van Hoeyveld
authors.affiliation: Laboratory Medicine, Immunology, University Hospitals, KU Leuven, Belgium.
authors.forename: Silvie
authors.initials: S
authors.lastname: Nickmans
authors.affiliation: Allergy and Clinical Immunology, University Hospitals, KU Leuven, Belgium.
authors.forename: Jan L
authors.initials: JL
authors.lastname: Ceuppens
authors.affiliation: Laboratory Medicine, Immunology, University Hospitals, KU Leuven, Belgium. Electronic address: xavier.bossuyt@uz.kuleuven.be.
authors.forename: Xavier
authors.initials: X
authors.lastname: Bossuyt
mesh_terms: D000485:Allergens / Q000276:immunology*; D029662:Betula / Q000276:immunology*; D005260:Female; D015200:Fluoroimmunoassay; D006801:Humans; D007124:Immunoenzyme Techniques; D007073:Immunoglobulin E / Q000032:analysis* / Q000276:immunology; D008297:Male; D006109:Poaceae / Q000276:immunology*; D011058:Pollen / Q000276:immunology*; D011446:Prospective Studies; D012220:Rhinitis / Q000175:diagnosis / Q000276:immunology; D006255:Rhinitis, Allergic, Seasonal / Q000175:diagnosis* / Q000276:immunology*
chemical_list: D000485:Allergens; D007073:Immunoglobulin E
keywords: Birch pollen allergy; Grass pollen allergy; Likelihood ratio; Specific IgE