D3.189 - Adverse reactions to subcutaneous immunotherapy for mite in children and adolescents in a tertiary care center

Allergen-specific subcutaneous immunotherapy (SCIT) is an effective and safety treatment for allergic diseases and is associated with a low incidence of severe adverse reactions. However, mild local reactions are frequent. Objective: To describe the adverse reactions per dose of conventional subcutaneous immunotherapy for mites.

Observational and descriptive study. Data collection was performed from June to October 2024 through a questionnaire in REDCap (Research Electronic Data Capture), answered by patients after each dose of SCIT. The sample included patients with previous diagnoses of atopic dermatitis, allergic asthma, allergic rhinitis, and/or allergic conjunctivitis, undergoing regular treatment with SCIT for mites, in the build-up or maintenance phase, aged between 4 and 21 years, attending the Allergy Clinic in a tertiary care center in the Federal District in Brazil.

A total of 412 questionnaires were collected, 408 (99.03%) with allergic rhinitis, 329 (79.85%) with allergic asthma and 196 (47.57%) with atopic dermatitis. Regarding the exacerbation of atopic conditions in the 3 days prior to the administration of the dose of SCIT, 339 (82,82%) denied symptoms, 46 (11.17%) reported allergic rhinitis crisis, 19 (4.61%) atopic dermatitis crisis, and 7 (1.70%) asthma crisis. Adverse reactions occurred in 150 (36.41%) of the doses, 57 (13.83%) immediate reactions and 93 (22.57%) late reactions. Local reactions occurred in 138 (33.49%) doses and small local reactions (less than 25 mm) happened in 56 (13.59%) doses. Systemic reactions occurred in 26 (6.31%) doses, with a predominance of nasal symptoms in 17 (4.13%) doses. The association between the exacerbation of atopic conditions 3 days before SCIT and adverse reactions was not significant. In multivariate logistic regression analysis, female sex (p=0,001) and higher concentration of mite immunotherapy extract (p=0,017) were risk factors for adverse reactions. Considering the occurrence of systemic reactions, the build-up phase (p=0,044) was the only risk factor identified.

Our results reinforce the literature data on the safety of immunotherapy in pediatric patients, highlighting that local reactions are common. Systemic and severe reactions can occur but are rare and were not observed in this study. Adverse reactions in SCIT are rarely reported in Brazil, which hinders statistical analyses in our population, further supporting the relevance of this work.