Sensitivity and Specificity of Prick and Intradermal Testing in Predicting Response to Nasal Provocation with Timothy Grass Antigen

Abstract

OBJECTIVE: Examine the efficacy of epicutaneous and intradermal testing in predicting response to nasal provocation with timothy antigen. STUDY DESIGN AND SETTING: Prospective study. Subjects were tested with Multi-Test II (MT). Subjects with negative wheals were tested with a 1:500 intradermal injection of timothy. They had baseline assessment of nasal cross-sectional area (CSA) using acoustic rhinometry and underwent nasal provocation with increasing timothy concentrations. CSA was assessed and nasal visual analog scale (VAS) completed with each concentration. RESULTS: Sensitivity and specificity of MT in predicting nasal response to provocation were 87% and 86%. Intradermal testing increased sensitivity to 93%. Hierarchical linear modeling (HLM) demonstrated that subjects positive to skin testing had significant reductions in CSA and worsening VAS scores with increasing concentrations of nasally delivered antigen. CONCLUSION AND SIGNIFICANCE: Epicutaneous testing with the Multi-Test II offers 87% sensitivity and 86% specificity in assessing timothy grass reactivity.