title: Analysis of allergen specific IgE cut points to cat and dog in the Childhood Allergy Study.
abstract: BACKGROUND
  The application of a single allergen specific IgE (sIgE) cut point, such as 0.35 kU/L, to determine sensitization for all allergens may be suboptimal.
  
  
  OBJECTIVE
  To analyze self-reported symptoms suggestive of dog and cat allergy in relation to the test performance characteristics of low level, but reliably detectable, sIgE and to compare these cut points to the traditional 0.35-kU/L cut point.
  
  
  METHODS
  Interviews and blood samples were collected among 564 young adult participants of a general risk birth cohort. Data collected from the participants' parents were analyzed as validation populations. A history of symptoms consistent with allergy on exposure to pets was obtained by standardized questionnaire. Allergen sIgE levels for dog and cat were evaluated with Pharmacia CAP. Receiver operating characteristic curves were constructed and the performance characteristics of the traditional sIgE cut point of 0.35 kU/L were compared with cut points as low as 0.1 kU/L.
  
  
  RESULTS
  Using the Youden J criteria, based on the highest sum of sensitivity and specificity for a diagnostic test, cut points of 0.12 kU/L for cat and 0.2 kU/L for dog were identified as performing optimally among the participant population. In 2 validation populations, consisting of the participants' mothers and fathers, the performance of these alternative cut points were superior or similar to the traditional 0.35-kU/L sIgE level.
  
  
  CONCLUSIONS
  Accurately measured sIgE at levels approaching the lower limit of detection of current assays may be useful in confirming sensitization. Optimal clinical application of these tests will continue to require careful integration of the result and the strength of the patient's history.
authors.affiliation: Henry Ford Health System, Detroit, Michigan, USA. carey.linden@yahoo.com
authors.forename: Carey C
authors.initials: CC
authors.lastname: Linden
authors.forename: Rana T
authors.initials: RT
authors.lastname: Misiak
authors.forename: Ganesa
authors.initials: G
authors.lastname: Wegienka
authors.forename: Suzanne
authors.initials: S
authors.lastname: Havstad
authors.forename: Dennis R
authors.initials: DR
authors.lastname: Ownby
authors.forename: Christine C
authors.initials: CC
authors.lastname: Johnson
authors.forename: Edward M
authors.initials: EM
authors.lastname: Zoratti
mesh_terms: D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000276:immunology*; D000818:Animals; D002415:Cats / Q000276:immunology*; D004285:Dogs / Q000276:immunology*; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000209:etiology*; D007073:Immunoglobulin E / Q000097:blood*; D008297:Male; D012882:Skin Tests; D055815:Young Adult
chemical_list: D000485:Allergens; D007073:Immunoglobulin E