An Exploratory Analysis of the Correlation Between Erythema Size and Total Nasal Symptom Scores in the Environmental Exposure Unit.
Monday, March 7, 2016
South Exhibit Hall H (Convention Center)
Lisa M. Steacy, BSc, Terry J Walker, BA, Barnaby Hobsbawn, Daniel Adams, BSc, Abhijeet Joshi, B.Pharm, MBA, Atul Raut, MD, PhD, Anne K. Ellis, MD MSc FAAAAI

Traditionally, wheal size has been used in studies conducted in the Environmental Exposure Unit(EEU), and other Controlled Allergen Challenge Facilities(CACF), for determining participant’s eligibility. It has been suggested anecdotally, however, that erythema diameter in the ‘wheal and flare’ reaction may be more indicative of allergic response than wheal size.  The goal of this analysis was to examine the relationship between the longest measured length of skin prick test(SPT) erythema to the Total Nasal Symptom Score (TNSS) achieved in the EEU after both 2 and 3 hours of ragweed pollen exposure during the first Priming Visit and the first 2 hours during a Baseline Challenge Visit.


This analysis was part of a larger study involving the EEU and ragweed allergic participants.  From the original data set collected of 222 randomized subjects we isolated 142 subjects who attended at least one priming visit (initial pollen exposure visit to activate allergic rhinitis  symptoms) and had SPT erythema data to ragweed on file.  The TNSS scores achieved at 2hrs on the Baseline Challenge day were also analyzed. Spearman’s correlation analysis of these data was performed using GraphPad Prism 6.0.


The correlation analysis showed no significant correlation between TNSS and erythema at the Priming Visit at 2hr(r=0.309) and 3hr(r=0.279) or the Baseline Visit at 2hr(r=-0.113).


Although it has been suggested that erythema may be a valuable predictor of allergic responsiveness in a CACF study, the correlation analysis performed has shown that erythema may not relate well to TNSS and further study may be warranted.