Evaluation of Risk Factors for Infections and Systemic Reactions (SRs) Associated with Subcutaneous and Sublingual Allergen Immunotherapy (SCIT and SLIT): AAAAI/ACAAI National Surveillance Study 2008-2015

Rationale: The risk of infections associated with SCIT is unknown. The aims of this study were to: 1) identify clinical practices that influence SRs to SCIT and SLIT; and 2) identify infections related to SCIT.  

Methods:   From 2008-2015, 27-51% of AAAAI and ACAAI members completed an annual survey of SCIT/SLIT-related SRs of varying severity (Grade 1= mild; Grade 2=moderate; Grade 3=severe; Grade 4=very severe).  From 2014-2015, members were queried about: local skin or systemic infections following SCIT requiring antibiotics; and selection of asthmatic patients for SCIT.   

Results: Between 2008-2015, data were gathered on 46.6 million injection visits.  Three directly reported fatalities were confirmed.  No local or systemic infections were reported in 9.5 million injection visits between 2014-2015.  Overall SR rates have trended down; however, more Grade 4 SRs were reported for 2013-2015 (1:160,000 injection visits versus 1:1 million in previous years).  Two-thirds (152/252) of Grade 3/4 SRs for 2014-2015 occurred in asthmatics (p<0.001); only 11% of practices reported >50% of SCIT patients were asthmatic.  For off-label SLIT, four Grade 3/4 SRs occurred in 2013-2015.  For FDA approved SLIT in 2014-2015 (1355 patients), two Grade 3 SRs were reported, one involving pharyngeal edema and another involving throat tightening and lower respiratory symptoms; both reactions were treated with epinephrine.   

Conclusions: No infections from SCIT were reported.  SCIT-related fatalities have remained low; however, there were more very severe SRs in recent years.  Asthma remains a major risk factor for severe SRs.  Both on and off-label SLIT may cause reactions requiring the use of epinephrine.