Abstract
Background: The diagnosis of human allergic disease begins with a thorough clinical history and physical examination. Once a temporal relationship has been identified between a patient's history of allergic symptoms and a defined allergen exposure, confirmatory analyses for IgE antibody involving skin or blood testing are performed to verify sensitization. Debate continues over the relative diagnostic utility of the in vivo and in vitro measures of IgE antibody. Objective: This overview examines the strengths and limitations of primary diagnostic confirmatory methods for in vivo detection (skin test, provocation test) and in vitro quantification of IgE antibody. Methods: A literature review was performed to examine diagnostic performance characteristics and variables that influence the accuracy of IgE antibody assays. Discussion: The clinical history and both in vivo and in vitro measures of IgE antibody are subject to variability and potential patient, clinician and technician-related bias. As such, in the absence of an absolute clinical history-based gold standard for defining the presence of allergic disease, the relative diagnostic performance (sensitivity, specificity) of in vivo versus in vitro assays of IgE antibody cannot be effectively determined. The review examines which allergic disease states and allergen specificities allow both groups of IgE antibody assays to produce comparable qualitative data for assessing the state of allergic sensitization. Skin testing has experienced few recent technological innovations, whereas an explosion has occurred in the improved performance (analytical sensitivity and specificity) of in vitro assays and enhanced quality of reagents for IgE antibody quantification. This review discusses the impact of point of care-testing assays, microarrays, the use of native and recombinant allergen molecules, automation, and disease prediction algorithms and the 2008 Clinical and Laboratory Standards Institute Guideline on IgE antibody methods, on the diagnosis of human allergic disease.