Peak nasal inspiratory flow as outcome for provocation studies in allergen exposure chambers: a GA2LEN study

Abstract

Background: The GA²LEN chamber has been developed as a novel mobile allergen exposure chamber (AEC) allowing standardized multicenter trials in allergy. Hitherto, subjective nasal symptom scores have been the most often used outcome parameter, but in standardized modern trials objective parameters are preferred. Despite its practicability, the objective parameter peak nasal inspiratory flow (PNIF) has been rarely used for allergy trials in the setting of allergen exposure chambers. This study aims to evaluate PNIF as an outcome parameter for provocation studies in AECs.

Methods: In a randomized controlled blinded setting subjects suffering from allergic rhinitis were exposed to grass pollen, birch pollen, house dust mite and/or placebo in the GA²LEN chamber. Different allergen concentrations were used to evaluate symptom severities. Patients had to perform PNIF before and every 30 min during a challenge using a portable PNIF meter.

Results: 86 subjects participated in 203 challenges, altogether. House dust mite provocations caused the greatest reduction in PNIF values, followed by grass pollen and birch pollen. Provocations with every allergen or pollen concentration led to a significant decrease (p < 0.05) in PNIF compared to baseline. Furthermore, positive correlations were obtained between PNIF and peak expiratory flow, height and weight, and inverse correlations between PNIF and total nasal symptom score, nasal congestion score and visual analog scale of overall subjective symptoms.

Conclusion: PNIF is a helpful and feasible tool for conducting provocation trials with allergens, especially grass pollen and house dust mite, in an AEC.

Keywords: Allergen exposure chamber (AEC); Allergy trial; GA2LEN chamber; Peak nasal inspiratory flow (PNIF); Provocation study.

Fig. 1

Reduction of PNIF during exposure with grass pollen in the GA²LEN chamber. PNIF development during exposure with Phleum pratense. A hash marks a reduction compared to baseline p < 0.001, a dagger a reduction compared to baseline p < 0.01. Outliers are presented as degree sign, extreme outliers as asterisk. PNIF% from both actively exposed groups (4000 and 8000 grains/m³) is significantly lower (p < 0.05) than in the placebo group at every associated time of measurement. PNIF% is displayed as medians and boxplots

Fig. 2

Reduction of PNIF during exposure with birch pollen in the GA²LEN chamber. PNIF development during exposure with Betula pendula. A hash marks a reduction compared to baseline p < 0.001, a dagger a reduction compared to baseline p < 0.01 and a double dagger a reduction compared to baseline p < 0.05. Outliers are presented as degree sign, extreme outliers as asterisk. PNIF% is displayed as medians and boxplots

Fig. 3

Reduction of PNIF during exposure with house dust mite (Der p 1) in the GA²LEN chamber. PNIF development during exposure with house dust mite material. A hash marks a reduction compared to baseline p < 0.001, a dagger a reduction compared to baseline p < 0.01. Outliers are presented as degree sign. PNIF% from the actively exposed group (250 µg/m³) is significantly lower (p < 0.05) than in the placebo group at every associated time of measurement. PNIF% is displayed as medians and boxplots

Fig. 4

Correlations between peak nasal inspiratory flow (PNIF) and oral peak expiratory flow (PEF) (a), height (b), and weight (c) with n = 86, and relative peak nasal inspiratory flow compared to baseline (PNIF%) and mean VAS change from baseline (d), mean Total Nasal Symptom Score (TNSS) (e), and mean nasal congestion score (f) with n = 203