BackgroundThere is no description of the drivers of prescription for allergen immunotherapy (AIT) for respiratory allergic diseases.MethodsA prospective, multicentre, observational, non-interventional real-life study was performed in France and Spain for 20 months. Data were gathered using 2 different questionnaires, anonymously collected in an online platform. No names of AIT products were recorded. Multivariate analysis and unsupervised cluster analysis were performed.ResultsOne hundred and three physicians (50.5% from Spain and 49.5% from France) reported 1735 patients (433 in France and 1302 in Spain), 47.9% males, 64.8% adults with a mean age 26.2 years old. They suffered from allergic rhinitis (99%), allergic conjunctivitis (70.4%), allergic asthma (51.8%), atopic dermatitis (13.9%), and food allergy (9.9%). A clustering analysis based on 13 predefined relevant variables for AIT-prescription identified 5 different clusters, each of them including information regarding doctor's profile and patient demographics, baseline disease characteristics, and main AIT indication: 1) Looking at the future: focusing on asthma prevention (n = 355), 2) Efficacy after discontinuation of AIT (n = 293), 3) Fighting severe allergic disease (n = 322), 4) Looking at the present, facing current symptoms (n = 265) and 5) Doctor's own clinical experience (n = 500). Each one of these clusters have specific patients' and doctors' characteristics, representing distinctive AIT prescription drivers.ConclusionUsing data-driven analysis, we identified for the first time some reasons and patterns of AIT prescriptions in real-life clinical settings. There is no uniform indication for prescribing AIT, which varies amongst patients and doctors with multiple but specific drivers, taking into account several relevant parameters.