D3.188 - Comparison of Completion Rates and Factors Influencing Discontinuation in Paediatric Allergen Immunotherapy: A Five-Year Single-Center Experience

Allergen immunotherapy (AIT), administered via subcutaneous (SCIT) and sublingual (SLIT) routes, is a well-established treatment for allergic conditions. Rates of adherence and completion to SCIT are traditionally higher [1],[2]. After provision of information on both treatment options, treatment choice was decided by clinician-determined suitability, family preference and service availability. This study aimed to establish completion rates and potential key factors influencing AIT discontinuation for SCIT and SLIT in this paediatric allergy population.

A retrospective cohort study was conducted on paediatric and adolescent patients aged 5-19 years who underwent AIT for aeroallergen sensitivity in the context of severe allergic rhinitis (house dust mite, grass pollen, tree pollen and animal dander) between 2017 and 2021 in our department. Patients who discontinued therapy were analysed to assess reasons for non-completion. Fisher’s exact test was used to compare failure reasons between SCIT and SLIT.

A total of 160 patients commenced AIT, with the majority on SLIT (78.7% vs. 21.3% on SCIT). The overall completion rate for SLIT was 63.5%. At the start of the treatment the median age of SLIT non-completers (11 years, range 5–17) was similar to those who completed the treatment (10.3 years, range 5–19). Among the 54 patients who did not complete SLIT, 14 switched to SCIT, and most successfully completed the treatment (12/14), while 2 patients restarted with a different formulation and completed treatment successfully.

Moreover, the overall completion rate was higher for SCIT, 83.3%. The median age of SCIT non completers (14.5 years, range 7-17) was higher than those who completed the treatment (12years, range 7-19). Of the 6 patients who did not complete SCIT, 1 transitioned to SLIT and completed it successfully.

For SLIT drop outs (36.5%, n=46), adverse reactions (47.8%) and poor compliance (41.3%) were the most frequently reported causes. Among SCIT not completing treatment (n=6), poor compliance (4/6) and adverse reactions (2/6), including two cases of anaphylaxis  were the primary reasons for discontinuation. Statistical analysis showed no significant difference in the distribution of failure reasons between SCIT and SLIT (p>0.05 for all comparisons). 

SCIT demonstrated a higher completion rate than SLIT in this cohort. The underlying reasons for treatment failure, adverse reactions and poor compliance, were comparable in both groups. Notably, transitioning between SLIT and SCIT contributed to a higher overall treatment completion rate. Future research should explore strategies to improve adherence and minimize adverse effects, improving the success rates of AIT.