Risk factors for fatal and nonfatal reactions to immunotherapy (2008-2018): postinjection monitoring and severe asthma

Background Subcutaneous allergen immunotherapy (SCIT) is highly effective but risks exist. Objective To identify practices that influence systemic allergic reactions (SRs) to SCIT and SCIT-associated infections. Methods Members of the American College of Allergy, Asthma and Immunology and the American Academy of Allergy, Asthma and Immunology completed an annual survey of SCIT-related SRs of varying severity (2008-2018). Injection-related infections were queried (2014-2018). Strategies to enforce postinjection waiting times and to reduce risks from asthma/severe asthma were queried (2016-2018). Results Data were gathered on 64.5 million injection visits. Ten confirmed fatalities occurred since 2008, including 3 new fatalities since 2017. One fatal reaction occurred per 7.2 million injection visits (2008-2018). No infections occurred. Practices that tracked the time after injections, and required checking out with office personnel, had significantly lower total (P < .001), grade 3 (severe) (P < .001), and grade 4 (very severe) SRs (P < .001). Having more individuals with asthma on SCIT was associated with more grade 3 SRs (P < .02). Not prescribing SCIT in individuals with uncontrolled asthma was associated with fewer grade 3 SRs (P = .02). Having individuals with more severe asthma on SCIT was associated with more total, grade 1, and grade 2 SRs (P < .001); 50% of grade 3 and 4 SRs occurred in individuals with severe asthma. Conclusion SCIT-related fatalities have declined since 2008, with a slight increase in recent years. SCIT is not associated with an increased risk of infections. Tracking the time after injections and checking out with office staff confer significantly lower risks of severe SRs. Asthma, especially severe asthma, is a major risk factor for severe and fatal SRs. Strategies that reduce risks for individuals with asthma, such as not prescribing SCIT to patients with uncontrolled asthma, may lower the risks.