Strengths and limitations
The study was limited to 1 year. Therefore, AEs that developed, subsequently, may be missed. Since previous studies have shown that most (serious) AEs occur at the beginning of treatment and AEs decrease over time from 51.8% at day 1 to 5.8% after 1 year in this study, we consider this risk to be low.
138 out of 415 patients did not complete the study. Discontinuation of treatment is a common problem when administering SLIT. This might have had impact on our outcomes i.e. there could be an underestimation of the safety and tolerability effects and an overestimation of effectiveness. Nonetheless, no major differences were observed in baseline characteristics of patients that continued versus those that discontinued treatment, indicating that outcomes are representative for all patients.