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.