Children are not little adults: The increased frequency of systemic reactions to subcutaneous immunotherapy (SCIT) in a pediatric allergic population

ABSTRACT

Case Report Background: The pediatric population represents 35% of all atopics (Chad et al. 2001). SCIT has been shown to be effective in pediatrics in the management of Allergic Rhino-Conjuncitvitis (ARC), (Kim et al. 2013). Debate continues in dosing regimes (Arasi et al. 2018) and the true reporting of pediatric SCIT induced Systemic Reactions (SR). As SR's, mild to severe bronchospasm ranges from 1-30% and unspecified systemic reactions between 3-34% (Kim et al. 2013). This retrospective study aimed at illustrating the frequency of aeroallergen SCIT induced adverse reactions in a pediatric population. Method: Data was obtained from pediatric patients (PP) attending a community allergy clinic for aeroallergen SCIT. Recorded data included the following demographics, diagnosis, allergen, administered dose and occurrence of adverse reactions over the last 5 years. SCIT doses were administered in accordance with Canadian Society of Allergy and Clinical Immunology guidelines and SR were graded as per World Allergy Organization guidelines (Cox et al. 2010). Patients on Vespid immunotherapy were excluded. Results: SCIT data was reviewed over 5 years. Out of a total of 97 SCIT patients, 23 were pediatric (mean age of 11.2 years 95% CI, 10.12 to 12.28). Of all pediatric patients, 9% received single allergen immunotherapy, 91% received multi-allergen immunotherapy. Ten of the 23 PP sustained adverse reactions to SCIT. Clinically significant large local reactions requiring dose reduction were reported in 3 PP (13%), while SR were noted in 7 PP (30%), 4 classified as Grade 1 and 3 as Grade 2. SR occurred in 4/7 (57%) PP on a build-up regime and 3/7 (43%) on maintenance dosing. Six PP with SR continued on SCIT with modified dosing regimes, 1 discontinued therapy because of current COVID-19 concerns. Two of the 23 PP completed the duration of therapy with no reactions and were discharged from follow up care. During the same time period, SR occurred in 6/74 (8.1%) adult patients. In comparison to adults undergoing SCIT, the rate of SCIT induced SR in the pediatric population was three times higher. Conclusion: In general, the rate of SCIT-associated SR of varying severity is low (James et al. 2017). However, in PP, our study reported a significantly higher occurrence of SR compared to adults on SCIT over the same time period. Additional research is required to tailor conventional build-up and dosing to a pediatric population to address higher rates of SR in this population.