An update on allergen immunotherapy

Abstract

AAllergen-specific immunotherapy (AIT) has been used to treat allergic diseases for over a century. It is the only treatment that addresses immune dysfunction underlying allergic responses rather than simply treating symptoms or suppressing inflammation. Its safety and efficacy in allergic rhinitis, asthma and insect allergy has been documented in a number of systematic reviews but its cost effectiveness is less clear. AIT reduces symptoms and requirement for medication, while improving quality of life. Further, the effect continues for years after discontinuation of treatment. However, evidence regarding cost effectiveness is limited. During AIT, allergen extracts are administered through a subcutaneous or sublingual route for 3-5 years. Subcutaneous immunotherapy is more effective in inducing long-term remission but systemic reactions do occur occasionally. Sublingual immunotherapy is safer and more convenient for the patient but evidence regarding its long-term efficacy is patchy. AIT is used widely in western Europe and the USA. In the UK, subcutaneous immunotherapy is often used for bee and wasp allergy, while both subcutaneous and sublingual immunotherapies are used for severe allergic rhinitis and occasionally for house dust mite and pet allergies. In conclusion, AIT is safe and effective and should be considered as a treatment option for those with allergic diseases.

Subcutaneous and Sublingual Immunotherapy in Allergic Asthma in Children

“…In this context, an observational multicenter survey carried out by the Italian Pediatric Allergy Network suggest that a higher cutoff point of SPT-induced wheal reactions (e.g., 5 mm) should be used to take decisions when a confirmatory CRD assay cannot be implemented ( 32 ). In the UK, AIT is rarely used for asthma, partly because of the risk of adverse reaction with SCIT in uncontrolled asthma, and partly because of the lack of evidence for its cost-effectiveness versus the currently available routine treatments ( 33 ). Several factors may influence the decision for immunotherapy either way, such as poor adherence, clinically irrelevant allergens, poly-sensitizations, unavoidable adverse reactions of routine medication, etc.…”

A critical appraisal on AIT in childhood asthma

“…The recent ARIA guidelines [ 44 ] suggest both SCIT and SLIT as a conditional recommendation in allergic asthma, due to the moderate/low quality of evidence. The lack of robust evidence led to a certain grade of opposition to the use of AIT in asthmatics [ 45 ]. Indeed, the potential benefits of AIT must be weighed against the risk of adverse effects, the inconvenience and cost of a prolonged course of therapy, as stated by the 2017 Global Initiative for Asthma Report [ 46 ] considering also other factors such as poor adherence, clinically non relevant allergens, poly-sensitizations, unavoidable adverse reactions of routine medication, etc [ 47 ].…”

Chinese Guideline on allergen immunotherapy for allergic rhinitis

“…The mechanisms of AIT are still not fully understood (83). AIT is based on administration of gradually increasing concentrations of allergen extracts and leads to the development of clinical allergen tolerance in selected patients.…”