Patients
Patients meeting the following criteria were included in the overall AIT group: age ≥5 and ≤65 years; received at least one prescription of a symptomatic AR medication during the pre-index period (see Figure 1); received treatment with one of the selected AIT products with at least four prescriptions in ≥3 consecutive pollen seasons between index date and end of year 5; initiated treatment with one of these products between September 2009 and August 2013; and ≥2 years of follow-up after treatment.
Each AIT group has a matched control group with patients between the age ≥5 and ≤65 years with AR and/or asthma with at least three prescriptions of symptomatic AR medication in three successive allergy seasons (September to August) and with at least two years of follow-up.
Patients were excluded if they had received any specific immunotherapy in the entire database history (January 2008 to June 2020); had severe asthma (defined as having prescriptions of biologics for asthma) or perennial asthma [defined as ≥3 prescriptions of inhaled corticosteroids (ICS), long-acting ß2-agonists (LABA) in combination with inhaled corticosteroids, Theophylline or leukotriene receptor antagonists (LTRA), distributed over any three successive 4‐month periods before the index date]; if they had COPD-specific maintenance medication in the entire database history; if they had extreme (0.25% of largest) values in terms of number of AR, allergic conjunctivitis (AC) or anti-asthmatic prescriptions during pre-index or follow-up period or if they had prescriptions of allergens of the focus product of both grass and tree pollen (Table S 1 and Table S 2).
Patients in the different control groups underwent exact matching with those in each AIT group. More than 58% of the patients were matched based on all defined covariates. Subsequently in separate matching steps covariates were removed to match the remaining patients. Details can be found in the supplemental Table S3.