Participants
Individuals on file from previous enrolment in studies with the Allergy Research Unit of KGH were approached to participate in this study. Inclusion criteria for the allergic population included males or females between the ages of 18–65 years, a minimum 2 year documented history of allergic rhinoconjunctivitis symptoms during the typical tree pollen season (mid-April to early June), and have a positive skin prick test (SPT) to birch allergen at screening with a wheal diameter ≥5 mm than the negative control. Participants had to be willing and able to provide written informed consent and comply with study requirements. Additionally, sexually active women of childbearing potential were asked to use a medically acceptable method of birth control, and produce a negative urine pregnancy test at screening. Non-allergic participants had to meet the same criteria except for the history of AR and were required to have negative skin test responses to a panel of common environmental allergens, including birch.
Exclusion criteria for all participants included having an upper respiratory tract infection within 1 week of pollen exposure, participants with asthma requiring the use of a short-acting beta agonist greater than twice a week, or anyone with a history of birch-pollen induced asthma, regardless of severity, or a history of any disease that in the judgement of the investigator would impact on the participant’s safety. Similarly, participants were excluded if they had a history of positive test results for Hepatitis B, Hepatitis C, HIV, or tuberculosis (other than due to vaccination), or significant history of drug or alcohol abuse or other clinically relevant abnormalities on physical exam. Other exclusion criteria were females who were pregnant, actively trying to become pregnant, or currently lactating. Participants were also asked to observe washout periods for medications listed in Table
1.
Table 1
Washout periods for medications
Beta-blockers, alpha-adrenoceptor blockers, currently receiving allergen immunotherapy | Not permitted |
Topical alpha-adrenergic agonists | 48 h |
H1 receptor antagonists | 7 days |
Topical corticosteroidsa
| 7 days |
Anticholinergics | 7 days |
Intranasal or inhaled corticosteroids | 14 days |
Intranasal or inhaled cromolyn | 14 days |
Tricyclic antidepressants and monoamine oxidase inhibitors | 14 days |
Leukotriene inhibitors | 14 days |
Systemic corticosteroids (oral) | 30 days |
Depot corticosteroids | 60 days |
The study was reviewed and ethics clearance granted by the Queen’s University and Affiliated Teaching Hospitals Research Ethics Board (REB), and was registered at clinicaltrials.gov (NCT02351830).
Study design
The study was conducted outside of pollen season (February 2015). At the screening visit, participants provided written informed consent and had their vital signs, height and weight measured. A medical history was taken and physical examination, including nasal examination, was conducted. SPT was performed on the volar surface of the participant’s forearm for the following allergens: Birch, timothy grass, rye grass, short ragweed, tree mix, dog, cat, dust mite (D. pteronyssinus, D. farinae), and Alternaria mould.
Qualified participants were invited back to the EEU for one 4 h birch pollen exposure session. Before the exposure, the inclusion and exclusion criteria were reviewed and an infectious disease questionnaire was completed by the participants to ensure they were in good health. Women of childbearing potential were required to have a negative pregnancy test.
Participants were seated inside the EEU and birch pollen (Greer, NC) was delivered and maintained at a concentration of 3500 ± 500 grains. The pollen concentration was determined every 30 min using seven Rotorod® samplers placed at specific locations and the pollen emission rate was then modified based on the Rotorod® counts to maintain equal distribution of the pollen throughout the facility. Other environmental factors were controlled during the exposure period as described earlier.
Participants used either paper diary cards or electronic tablets [
21] to record their total nasal symptom score (TNSS) at baseline and at 30 min intervals for the duration of the exposure, then hourly up to 12 h from the start of pollen exposure. Participant symptoms were captured using both paper diary cards and as electronic patient-reported outcomes (ePRO) recorded on tablets. Both means to capture the participants’ symptoms resulted in data being stored in our validated Clinical Trial Data Management System. All participants recorded their symptoms from hours 4–12 on paper diary cards and mailed them back to the site upon completion. At each time point participants graded their symptoms on a scale from 0 to 3, including sneezing, runny nose, itchy nose, and congestion, for a total out of 12 (Table
2). Participants also recorded ratings of symptom severity for itchy ears/palate/throat, itchy/gritty eyes, red/burning eyes, and teary eyes, and these scores, in addition to the TNSS, comprised the Total Rhinoconjunctivitis Symptom Score (TRSS) for a maximum score of 24. Participants were trained to measure peak nasal inspiratory flow (PNIF) using a facial mask and meter (InCheck, Clement Clarke International Ltd, Essex, UK), taking three measurements at each time point. The greatest of the three measurements was used as the final measure of air flow.
Table 2
Symptom score definitions
0 = none | Symptom is completely absent |
1 = mild | Symptom is present but minimal awareness, easily tolerated |
2 = moderate | Awareness of symptoms, bothersome, but tolerable and not interfering with daily activities |
3 = severe | Definite awareness of symptoms, difficult to tolerate, interferes with activities; and/or desires treatment |
Biological samples were collected during this study, including nasal brushing for sampling epithelial cells and blood samples for PAX gene analysis and CBC differentials. The results from these analyses will be reported in future submissions.
Statistical analysis
GraphPad Prism 6.0 (San Diego, CA, USA) was used for the statistical analysis of the data. TNSS, TRSS, and PNIF data from allergic and non-allergic participants were compared using two-way repeated measures ANOVA with Bonferroni’s correction. Comparisons of scores at different points to baseline was completed using one-way repeated measures ANOVA with Tukey’s correction. The percentage reduction in PNIF at each time point compared to baseline was used to compare allergic and non-allergic groups.