Defining pollen exposure times for clinical trials of allergen immunotherapy for pollen-induced rhinoconjunctivitis - an EAACI position paper

Background Clinical efficacy of pollen allergen immunotherapy has been broadly documented in randomized controlled trials. The underlying clinical endpoints are analysed in seasonal time periods pre-defined on the basis of the background pollen concentration. However, any validated or generally accepted definition from academia or regulatory authorities for this relevant pollen-exposure intensity or period of time (season) is currently not available. Therefore, this Task Force initiative of the European Academy of Allergy and Clinical Immunology (EAACI) aimed to propose definitions based on expert-consensus. Methods A Task Force of the Immunotherapy and Aerobiology and Pollution Interest Groups of the EAACI reviewed the literature on pollen-exposure in the context of defining relevant time intervals for evaluation of efficacy in allergen immunotherapy trials. Underlying principles in measuring pollen exposure and associated methodological problems and limitations were considered in order to achieve a consensus. Results The Task Force achieved a comprehensive position in defining pollen exposure times for different pollen types. Definitions are presented for ‘pollen season’, ‘high pollen season’ (or ‘Peak pollen period’) and ‘high pollen days’. Conclusion This EAACI position paper provides definitions of pollen exposures for different pollen types for use in Allergen Immunotherapy trials. Their validity as standards remains to be tested in future studies. This article is protected by copyright. All rights reserved.