Systemic and large local reactions during subcutaneous grass pollen immunotherapy in children

Background Subcutaneous immunotherapy (SCIT) is the allergen-specific curative treatment of allergic rhinitis. Adverse effects, most of which are local, can be observed during the immunotherapy. These adverse effects have been reported more frequently during the pollen season. The purpose of this study was to estimate the rate of local, large local, and systemic reactions during the treatment, to determine the relationship between adverse reactions and the season in which these reactions occur, as well as the risk factors for adverse reactions during the grass pollen-specific SCIT treatment in children. Methods We retrospectively collected and analyzed the data of 261 children who administered grass pollen SCIT between 2008 and 2018. Results A total of 261 children (177, 67.8% male), who received grass pollen SCIT, with a mean (+/- SD) age of 12.0 +/- 3.0 years at the initiation of SCIT were enrolled to the study. The number of the patients who experienced local and large local reactions was 109 and 30, respectively. In addition, the number of the patients with systemic reactions was 35. After the 12 284 injections, local reactions occurred in 357 (2.9%), and this was followed by systemic reaction as 55 (0.4%) and large local reactions as 40 (0.3%). Frequency of local (P 001) and systemic reactions (P = .003) was higher during grass pollen season than out of the grass pollen season. In multivariate analysis, initiation of SCIT during the grass pollen season [OR:7.351, 95%CI:1.532-35.279, P = .013] and experiencing local reactions [OR:4.214, 95%CI:2.159-8.224, P < .001] were independent predictors for the development of large local and systemic reactions. Conclusion SCIT, in which only mild-to-moderate systemic reactions occurred, is safe for the treatment of allergic rhinitis in children. Our study revealed that previous local reactions and initiation of immunotherapy during the grass pollen season were the predictors for large local and systemic reactions during SCIT in children.