AAAAI/ACAAI surveillance study of subcutaneous immunotherapy, years 2008-2012: an update on fatal and nonfatal systemic allergic reactions

Abstract

Background: Before 2002, there were an estimated 3.4 fatal reactions per year to subcutaneous allergen immunotherapy (SCIT). Recent incidences of SCIT-related systemic allergic reactions (SR) and fatal reactions are not well defined.

Objective: To define the incidence of and clinical practices associated with SRs to SCIT and skin testing.

Methods: From 2008 to 2012, 27% to 49% of the American College of Allergy, Asthma, and Immunology and American Academy of Allergy, Asthma, and Immunology members completed an annual survey of SCIT-related fatal and nonfatal SRs of varying severity. A shortened version of the World Allergy Organization (WAO) classification system for SRs was adopted in 2011 (grade 1, mild; grade 2, moderate; grade 3, severe; grade 4, very severe). From 2011 to 2012, data were collected regarding nonfatal SRs to skin testing and strategies to lower the risk of SRs from SCIT.

Results: Between 2008 and 2012, data were gathered on 23.3 million injection visits. One confirmed fatality occurred in 2009. Overall SR rates remained stable at 0.1%. The rate of very severe, WAO grade 4, SRs was similar to previously reported rates of near-fatal reactions (1 in 1 million injections). Although almost one-third of practices experienced at least 1 SR from skin testing, no WAO grade 3 or 4 SRs from skin testing were reported. A lower target dose during cluster buildup before transitioning to maintenance may be associated with a lower risk of WAO grade 3 SRs (P = .07). Dose adjustment during pollen seasons was associated with fewer WAO grade 3 or 4 SRs (P < .001).

Conclusions: Although SR rates have remained stable and fatalities appear to be declining, continued vigilance regarding SCIT safety is recommended. Additional surveillance and study regarding methods to decrease the risk of severe SRs is warranted.

Keywords: Allergy shots; Anaphylaxis; Cluster immunotherapy; Pollen season; Subcutaneous allergen immunotherapy; Systemic reactions.