Immediate and delayed-onset systemic reactions after subcutaneous immunotherapy injections: ACAAI/AAAAI surveillance study of subcutaneous immunotherapy: year 2

Abstract

Background: Incidences of subcutaneous immunotherapy (SCIT) related systemic reactions (SRs) and fatal reactions (FRs) are not well defined, nor are delayed-onset SRs and their treatment.

Objectives: To estimate SCIT-related SRs/FRs, and the incidence and treatment of delayed-onset SRs.

Methods: In 2008 and 2009, American Academy of Allergy, Asthma & Immunology (AAAAI) and American College of Allergy Asthma & Immunology (ACAAI) members completed a survey about SCIT-related SR severity (grade 1 = mild; grade 2 = moderate; grade 3 = severe anaphylaxis). In 2009, members reported the time of onset and use of epinephrine (EPI), with early onset defined as beginning ≤30 minutes, and delayed onset beginning more than 30 minutes after injections.

Results: As in year 1, no FRs were reported during year 2 (630 total practices responded). Among 267 practices providing data on the timing of SRs, 1,816 early-onset SRs (86%) and 289 (14%) delayed-onset SRs were reported. Fifteen percent (226/1,519) of grade 1, 10% (54/538) of grade 2, and 12.5% (9/72) of grade 3 SRs were delayed-onset. Among early-onset SRs, EPI was given for 71% of grade 1, 93% of grade 2, and 94% of grade 3s. Among delayed-onset SRs, EPI was given for 56% of grade 1, 67% of grade 2, and 100% of grade 3s (P = .0008 for difference in EPI administration based on severity; P = .07 based on time of onset).

Conclusions: Delayed-onset SRs are less frequent than previously reported. Epinephrine was given less frequently for grades 1 and 2 (but not grade 3) delayed-onset SRs compared with early-onset SRs. Further study of prescribing self-injectable EPI for SCIT patients in the event of delayed-onset SRs may be warranted.

Figure 1.

Administration of epinephrine (EPI) in early versus delayed-onset systemic reactions (SRs). Early-onset SRs are those occurring at ≤30 minutes after injection; Delayed-onset SRs are those occurring at > 30 minutes. Gr1 = grade 1; Gr 2 = grade 2; Gr3 = grade 3. Data regarding timing, SR severity, and EPI use were available for 219 practices. For early-onset SRs, EPI was given for 912/1,293 grade 1 SRs, 450/484 grade 2 SRs, and 59/63 grade 3 SRs. For delayed-onset SRs, EPI was given for 126/226 grade 1 SRs, 36/54 grade 2 SRs, and 9/9 grade 3 SRs. *P = .0008 for the difference in EPI use based on SR severity. **P = .07 for the difference in EPI use based on the time of onset of the reaction.