Allergen immunotherapy for respiratory allergy: to what extent can the risk of systemic reactions be reduced?

ABSTRACT

Introduction

Allergen immunotherapy is an effective treatment for respiratory allergy, but the administration to patients of extracts of the causative allergen may elicit systemic reactions, which include, particularly with subcutaneous immunotherapy (SCIT), anaphylaxis. In the past, the occurrence (tough rare) of fatal reactions has represented a serious problem that has limited the prescription of SCIT.

Areas covered

The authors analyzed in this review the safety data of SCIT, especially concerning the years following the identification of uncontrolled asthma at the moment of allergen injection as the major risk of life-threatening reactions and fatalities. The safety of SLIT, which is far better than SCIT, was analyzed and its specific risk factors for systemic reactions were highlighted.

Expert opinion

Presently, the safety profile of SCIT and SLIT is satisfactory, provided the treatment is administered by physicians experienced in this treatment, who are aware of the known risk factors for severe reactions and who implement all measures to avoid them. For SLIT, which is self-administered by the patient, receiving the first dose under medical control is recommended.

KEYWORDS:

• Allergen immunotherapy
• subcutaneous route
• sublingual route
• safety
• respiratory allergy

Article highlights

• Allergen immunotherapy is the only treatment acting on the causes of allergy, but the administration of the culprit allergen may elicit systemic reactions, which include, particularly if the subcutaneous route is used, anaphylaxis.

• The most worrying safety aspect of SCIT has been the fatalities associated with severe anaphylaxis, which mostly concerned patients with uncontrolled asthma, the frequency of which significantly declined by avoiding the allergen administration in patient with such condition.

• Other risk factors are errors in administering SCIT, a history of prior systemic reactions to SCIT, and receiving the injection during the exposure to the specific allergen, as occurs for the pollen peak period.

• Sublingual immunotherapy is much safer, being mostly concerned by local reactions in the site of administration, while anaphylaxis is very rare. However, the guidelines recommend that the first dose of the allergen extract is administered under medical control.

• Based on the available data, the safety profile of allergen immunotherapy is suitable, provided the patient is monitored by expert physicians, who know the risk factors for severe reactions and are able to apply all procedures to avoid them.

This box summarizes key points contained in the article.

Declaration of interest

C Incorvaia is a scientific consultant for Stallergenes Italy. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was not funded.