Analysis of allergen specific IgE cut points to cat and XXXX in the Childhood Allergy Study.

@entity235 @entity566 @entity1 @entity9527
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. OBJECTIVES: To analyze self-reported symptoms suggestive of @entity235 and cat @entity566 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 @entity1 of a general risk birth cohort. Data collected from the @entity1 ' parents were analyzed as validation populations. A history of symptoms consistent with @entity566 on exposure to pets was obtained by standardized questionnaire. Allergen sIgE levels for @entity235 and cat were evaluated with Pharmacia @entity9527 . 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 @entity235 were identified as performing optimally among the @entity1 population. In 2 validation populations, consisting of the @entity1 ' 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 @entity1 's history.
