Analyzing Phenotypes Post-Exposure in Allergic Rhinitis (APPEAR) in the Environmental Exposure Unit (EEU).

Background: Previous studies have defined clinical phenotypes of allergic rhinitis (AR) after allergen exposure using the time course of the total nasal symptom score (TNSS).

Objective: We aimed to validate previously proposed AR phenotypes across different allergens (birch, grass, ragweed, house dust mite) following exposure in the Environmental Exposure Unit (EEU).

Methods: The Analyzing Phenotypes Post-Exposure in Allergic Rhinitis (APPEAR) database comprises 153 participants from EEU studies conducted between 2010-2021 by Kingston Allergy Research. TNSS, nasal congestion symptom scores, and percent change in peak nasal inspiratory flow from baseline (%ΔPB) were recorded for each participant. Participants were phenotyped using previously described criteria RESULTS: 65 participants (42.5%) were classified as Early-phase Responders (EPR), 58 (37.9%) as Protracted Early-phase Responders (pEPR), 13 (8.5%) as Dual Responders (DR), and 17 (11.1%) as Low Responders (LoR). Significant negative correlations exist between TNSS and %ΔPB (r = -0.99, p<0.0001), and nasal congestion symptom score and %ΔPB (r = -0.99, p<0.0001). At the beginning of the late-phase AR response (6 to 7 hours), pEPRs had significantly higher TNSS compared to EPRs, DRs, and LoRs (p<0.0001). By the end of the study (up to 12 hours), DRs and pEPRs had significantly higher TNSS compared to EPRs and LoRs (p<0.0001). Visible and statistical validity between the phenotypes were also confirmed by assessing participants' mean TNSS and mean %ΔPB over time when grouping by phenotype.

Conclusion: This study confirms distinct phenotypes exist in the late-phase AR response amongst different allergens and in a greater sample size than described previously, which could provide clinical benefit.