Progression of asthma
Eight of the RWD analyses examined the effectiveness of AIT on asthma progression for up to six years follow-up resp. the full analysis period of 9 years (15–19,21,22,25) showing more heterogenous results than those for progression of allergic rhinitis. In 4 studies all investigated AIT-groups required significantly fewer asthma prescriptions than the corresponding Non-AIT group (15,18,19,21) while other analyses failed to show significant effects for all AIT preparations, age groups, timepoints and/or endpoints (16,17,22,25). Investigating the effect over time by cross-sectional comparisons to the control group, one assessment found that during the years 4 – 6 significantly less AIT-treated patients required asthma medication whereas asthma prescriptions were significantly reduced for up to 7 years after starting AIT. In addition, in the AIT group there was a significantly increased likelihood of stepping asthma treatment down as well as a significantly lower risk of stepping up (25). For details see tables S5, S6, S7, S8 in supplementary information.