Mucosal brushings for nasal specific IgE to predict house dust mite driven allergic rhinitis

Background: Skin prick testing and serological identification of allergen specific immunoglobulin E (spIgE) are standard tests for allergic rhinitis but can only identify systemic responses. In contrast, nasal allergen challenge (NAC), directly assess localized nasal mucosal reactivity, but is time consuming. Identification of spIgE from nasal brushings (nasal spIgE) is an alternative technique. Objective: This study aimed to determine the diagnostic performance of nasal spIgE compared to NAC in order predict house dust mite (HDM) driven AR. Methods: A diagnostic cross-sectional study involving adult rhinitis patients was performed. Sensitization to HDM allergens (Dermatophagoides pteronyssinus (DP), Dermatophagoides farina (DF) were assessed serologically and/or skin prick test, nasal brushing and NAC. Patients with both positive systemic test and NAC were defined to have HDM driven AR, while patients with a positive systemic test and negative NAC were defined to have non-clinically relevant HDM sensitization. The performance of nasal spIgE to predict positive NAC was determined using the receiver operating curve. The chosen cut-off was then used to predict HDM driven AR among those with positive systemic test. Results: 118 patients (29.42 ± 9.32 years, 61.9% female) were included. Nasal spIgE was predictive of positive NAC (AUC 0.93, 95%CI: 0.88-0.98, p < 0.01). Among those with positive systemic test, the cut-off value of > 0.14 kUA/L was able to predict HDM AR from incidental HDM sensitization with 92% sensitivity and 86% specificity. Conclusion: Nasal spIgE is comparable to NAC. A cut-off value of > 0.14 kUA/L identifies HDM-driven AR from incidental sensitization among patients with positive systemic tests for allergy.