Are large local reactions a marker for systemic reactions to subcutaneous immunotherapy in children?

Background: Previous studies involving predominantly adults concluded that the patients developing frequent large local reactions (LLRs) might be at greater risk for systemic reactions (SRs) during subcutaneous allergen immunotherapy (SCIT). Objective: To determine the rate of side effects to SCIT and evaluate frequency of LLR among pediatric patients with SRs. Methods: The retrospective study included pediatric patients receiving SCIT. Data on the demographic features, season at onset of SCIT, the indication for treatment, additional allergic diseases, laboratory results, the allergens applied, side effects after injection, grade of SRs, and the total number of injections for each patient were collected retrospectively from the medical records and injection charts. Results: A total of 19,562 injections were administered to 261 patients with conventional SCIT. The incidence LLRs was 0.2% per injection; 1.15% of all patients (n = 3) experienced LLRs on at least two consecutive visits. Systemic side effects were seen in 1% of all SCIT injections. No grade 3 or grade 4 SRs were observed. Logistic regression analysis showed that having an LLR was 3.32 times (95% CI, 1.313-8. 440; P = 0.011) and initiation of SCIT in summer and spring was 4.309 and 3.056 times than autumn (95% CI, 1.527-12.157, P = 0.006; 95% CI, 1.358-6.849, P = 0.007), respectively, increased risk for an SR. Conclusion: Having LLRs might predict the risk of SRs at any time during immunotherapy in also pediatric patients. Knowing the risk factors is important for developing a personalized protocol in these patients.