Route of Allergen Immunotherapy: A Global Look Into Physicians' Motivations

Current Allergen Immunotherapy (AIT) guidelines provide no definitive guidance on route selection, whether subcutaneous (SCIT) or sublingual (SLIT). The primary objective of this study was to characterize real-world AIT prescription patterns, with emphasis on route selection, using a factor analysis approach in a large international cohort.

The CHOICE study is a real-life, multicentre, international, observational, cross-sectional web-based survey conducted across 20 countries between November 2019 and April 2024. Participating doctors completed standardized questionnaires for each consecutive AIT prescription. Thirteen patient-related and product-related parameters were analyzed using exploratory and confirmatory factor analysis. Latent factors identified were subsequently incorporated into multivariate mixed logistic regression models with country and physician nested within country as random intercepts.

Data from 467 physicians and 11550 patients were analyzed; 60.0% of prescriptions were SCIT and 40.0% were SLIT. Three latent factors were identified: (F1) Scientific and clinical evidence-Based; (F2) Resource and access optimisation; and (F3) Tailored for the patient and their lifestyle. When country was modeled as a random intercept, all three factors were significantly associated with SLIT prescription. After adjustment for both country and physician, F2 was associated with reduced probability of SLIT prescription (OR 0.42; 95% CI 0.31, 0.59), while F3 was strongly associated with an increased probability of SLIT prescription (OR 10.90; 95% CI 7.20, 16.57). Variability attributable to country (ICC 0.86) and physician (ICC 0.74) was high.

Patient-centred considerations increase the likelihood of SLIT use while considering the cost of the treatment increases the likelihood of SCIT use. Substantial variability in AIT route selection is attributable to country- and physician-level factors.