Repeatability of Total Nasal Symptom Scores (TNSS) in Allergic Rhinitis Individuals Using an Electronic Diary during Environmental Exposure Chamber (EEC) Visits

Rationale: EECs are used in allergic rhinitis models to assess clinical nasal symptom responses while circumventing the variability observed in outpatient field studies. In the present study, we evaluated the repeatability of TNSS during repeated exposure to the ragweed allergen during separate EEC visits.

Methods: Seventy-eight subjects with allergic rhinitis were exposed to ragweed pollen in the EEC at an interval of 27 (+5) days between visits. During the EEC visits, subjects recorded their total nasal symptoms using an electronic diary (ePDAT^®) prior to EEC entry and every 30 minutes over a 2 hour period.

Results: The mean TNSS levels at both Visits 1 and 2 increased and peaked at similar levels with average maximum TNSS scores (1^st visit = 8.86 ± 0.22; 2^nd visit = 8.37 ± 0.24). Consistent pollen levels were observed throughout the EEC visits. A highly significant correlation was shown of the overall average TNSS over time between Visits 1 and 2 (r = 0.9964, p = 0.0003). The average TNSS of each subject over both EEC visits showed a correlation coefficient of r = 0.5722, p<0.0001. In addition, a Bland-Altman plot had a mean difference of 0.6667 and 95% limits of agreement between -5.713 and 7.047 indicating a good clinical agreement between the two visits.

Conclusions: The ability of the EEC to elicit repeatable nasal symptoms at clinically significant levels in allergic rhinitis individuals will be a positive step forward in the evaluation of treatment outcomes and allergic rhinitis efficacy trials.