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

Abstract

BackgroundThe 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.MethodsIn 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.Results86 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.ConclusionPNIF is a helpful and feasible tool for conducting provocation trials with allergens, especially grass pollen and house dust mite, in an AEC.Electronic supplementary materialThe online version of this article (doi:10.1186/s13601-017-0169-4) contains supplementary material, which is available to authorized users.

Objectification of the nasal patency assessment techniques used in nasal allergen provocation testing

“…Peak nasal inspiratory flow evaluation is the second most common technique of nasal patency assessment as part of NPT and is an alternative to RMM [26]. The PNIF is a very useful parameter in assessing the effectiveness of immunotherapy in pharmacological studies, as well as in assessing nasal patency in the context of surgical procedures [27].…”

“…Inability to accurately interpret assessment findings may yield a false positive test result. A 7-hour observational study of spontaneous changes in nasal patency measured by a PNIF meter and RMM showed variability of the respective evaluated parameters by 15.78% and 26.38% [26]. This is why it is so important to bilaterally assess changes in nasal patency (following an earlier allergen application into both nostrils) and, at the same time, use a subjective grading of the patient's discomfort.…”

“…Peak nasal inspiratory flow evaluation is the second most common technique of nasal patency assessment as part of NPT and is an alternative to RMM [ 26 ]. The PNIF is a very useful parameter in assessing the effectiveness of immunotherapy in pharmacological studies, as well as in assessing nasal patency in the context of surgical procedures [ 27 ]. The PNIF testing is characterized by high sensitivity (higher than RMM) ranging from 66% to 77% and specificity of 80% (compared to RMM specificity of 77%) [ 11 ].…”

“…The PNIF meter is the most commonly used tool for nasal patency assessment and PNIF is measured predominantly in allergen exposure chambers [ 5 ]. Allergen-specific NPT with 4,000 grass pollen grains/m 3 exposure reduced the nasal patency (based on PNIF measurements) by 29.7%; 8,000 grass pollen grains/m 3 exposure reduced nasal patency by 36.8%, whereas in the control group the nasal patency was reduced by 8.9% [ 27 ]. The most recent allergen-specific NPT standards stipulate that a decrease in PNIF by ≥ 40% combined with a subjective discomfort rating of ≥ 55 mm (or ≥ 5 points) should be considered a highly positive result.…”

Highlights and recent developments in airway diseases in EAACI journals (2017)

“…Many allergen exposure chambers exist and a EAACI Position paper attempted to harmonize current concepts and projecting the needs for the future [ 26 ]. Peak nasal inspiratory flow was found to be as outcome for provocation studies in allergen exposure chambers in a GA 2 LEN study [ 27 ].…”