Lack of Harmonized Adherence Criteria in Allergen Immunotherapy Prevents Comparison of Dosing and Application Strategies: A Scoping Review

Abstract

Allergen immunotherapy (AIT) involves the application of increasing doses of allergen extract (as oral, sublingual, or subcutaneous immunotherapy) until immunologic tolerance is reached. Successful AIT relies on the consistent administration of allergen extract; therefore, adherence to these treatments is vital for compelling long-term results. Our review discusses the current terminology from adherence research in general, summarizes 25 current studies on adherence research in AIT in a scoping literature review, and delineates recommendations for tools and parameters for adherence research, aiming to improve outcomes in AIT. Almost every adherence study in AIT published to date used different tools, parameters, and data sources for measuring adherence and persistence rates. Unfortunately, an easily accessible, objective parameter or biomarker for monitoring treatment adherence and success has not yet been established for AIT. This situation calls for the development of an international core outcomes set for AIT that defines what is exactly meant by AIT adherence and how AIT adherence should be consistently measured. Therefore, we exemplarily present results and conclusions from adherence research in chronic diseases other than allergology. We aim to facilitate the development of advanced methods, considering the challenging disease specificities of these parameters in a routine care setting of AIT.