Study design
This study was a retrospective
data analysis using a German longitudinal prescription database (LRx,
IQVIA, Frankfurt am Main, Germany). The overall analysis period was
January 2008 to June 2020 (see Figure 1).
The index period for the study was defined from September 2009 to August
2013, including four allergy seasons (September to August). For the AIT
group, eligible patients were initiated on the respective SCIT products
at index date during this period. A pre-index period of 12 months before
SCIT initiation was determined. Treatment period lasted from index date
until expiry of the last prescription of the respective product followed
by the follow-up period of at least two years until end of the study in
June 2020.
For the control group, index date was defined as the first prescription
in the second allergy season during the index period. Treatment period
was from index date until expiry of the last prescription of the
respective product within a maximum of five years followed by the
follow-up period of at least two years until end of the study in June
2020.
Three authorized allergoids in Germany containing grass or tree pollen
were analysed: one MCT®-associated allergoid and two
aluminium hydroxide adjuvanted allergoids (allergoid 2 and 3,
respectively). For the control group symptomatic AR medications were
defined in accordance with the ARIA guideline 2019 .