Efficacy of allergen immunotherapy in reducing the likelihood of developing new allergen sensitizations: a systematic review

Background Guidelines and position papers indicate that allergen immunotherapy (AIT) is the only disease-modifying treatment, including prevention of the onset of new allergen sensitizations. However, this preventive effect was shown by only a few observational studies. Our aim was to systematically review the efficacy of AIT in preventing the onset of new allergen sensitizations. Methods Computerized bibliographic searches of MEDLINE, EMBASE, and the Cochrane Library (through June 2015) were supplemented with manual searches of reference lists. Observational studies or randomized controlled trials with a long-term observation period were included. Paired reviewers extracted data about study characteristics and assessed biases. The end-point was the risk difference in the onset of new allergen sensitizations between patients treated with AIT and pharmacotherapy. The strength of the evidence was graded based on the risk of bias, consistency, and magnitude of effect, according to the GRADE Working Group's guide. Results Eighteen studies (1,049 children, 10,057 adults) met the inclusion criteria. The risk of bias was high in all but one study. Low evidence supports the position that AIT prevents the onset of new allergen sensitizations, with 10 out of 18 studies reporting a reduction of the onset of new sensitizations in patients treated with AIT vs. placebo. Small studies and studies with a shorter follow-up showed the highest benefit of AIT. Conclusions The overall evidence provides a low-grade level of the evidence supporting the efficacy of AIT in preventing the onset of new allergen sensitizations, but high-quality studies could change this estimate. This article is protected by copyright. All rights reserved