Comorbidity of Allergic Asthma and Rhinitis and High Allergen-Specific IgE are Risk Factors for Systemic Reactions to House Dust Mite Immunotherapy in Children

Objective: To observe the adverse reactions during standardized dust mite allergen subcutaneous immunotherapy (SCIT) in children with allergic asthma (AA) and/or allergic rhinitis (AR), and to analyze the clinical characteristics and potential risk factors. Methods: This single-center retrospective cohort study included 250 children with allergic diseases who received house dust mite (HDM) SCIT treatment at our hospital from July 2022 to July 2025. The participants were divided into a systemic reactions (SRs) group and a non-SRs group. Differences in baseline clinical data and laboratory indicators between the two groups were compared, and independent risk factors for SRs were analyzed using the generalized estimating equation (GEE) method. Results: Among 250 children (9,244 injections), 114 (45.6%) experienced SRs, with an incidence of 3.47% per injection. SRs were predominantly characterized by immediate, mild grade I reactions, with only 2 cases of grade III reactions and no fatal or serious adverse events. The incidence of SRs during the maintenance period was higher than during the up-dosing period. Univariate analysis showed that the occurrence of SRs was associated with age 5– 9 years, AR combined with AA, elevated total immunoglobulin E (IgE), and high Dermatophagoides pteronyssinus (Der.p) specific IgE (sIgE) levels (P < 0.05). Multivariate GEE analysis showed that AR+AA comorbidity (compared to AA alone, odds ratio [OR] = 2.219, 95% confidence interval [CI]: 1.061– 4.638, P =0.034) and baseline Der.p.sIgE ≥ 17.5 IU/mL (OR = 2.233, 95% CI: 1.216– 4.099, P =0.01) were independent risk factors for SRs. Conclusion: HDM SCIT in children demonstrates a favorable safety profile, with SRs being predominantly mild and dose-dependent. The presence of AR+AA comorbidity (compared to AA alone) and a baseline Der.p.sIgE ≥ 17.5 IU/mL are key predictors of SR risk. These findings support pre-treatment risk stratification and suggest that children with these risk factors may benefit from a more individualized and monitored SCIT protocol to enhance safety. Keywords: allergic asthma, allergic rhinitis, subcutaneous immunotherapy, house dust mite, adverse reactions, pediatrics