The effect of allergen immunotherapy in the onset of new sensitizations: a meta-analysis

Background: Although the preventive efficacy of allergen immunotherapy (AIT) in the onset of new allergen sensitizations has been asserted by many reviews, position papers, and consensus conferences, the evidence available is from only 3 studies. The objective of this work was a systematic review to evaluate the preventive efficacy of AIT in the onset of new allergen sensitizations. The end-point was the risk difference (RD) in the onset of new allergen sensitizations between patients treated with AIT and pharmacotherapy. Methods: Computerized bibliographic searches of MEDLINE, EMBASE, and the Cochrane Library (until November 30th, 2016) were done. Random-effects and fixed-effects model meta-analyses were performed. Randomized controlled trials or observational studies comparing children treated with AIT with house dust mite (HDM) to subjects who did not receive AIT, with a long-term observation period (at least 3 years including treatment and follow-up) have been included. Results: Eight studies totaling 721 children (390 treated with AIT and 331 with pharmacotherapy) met the inclusion criteria. The risk of bias was high. Low evidence supports the conclusion that AIT prevents the onset of new allergen sensitizations, with 3 of 8 studies reporting a reduction in the onset of new sensitizations in patients treated with AIT vs pharmacotherapy. Our meta-analysis found no difference between AIT and pharmacotherapy, with high heterogeneity (RD, −0.10; 95% confidence interval [CI], −0.31 to 0.11; p = 0.32; I2 = 91.4%). Conclusion: The data of this systematic review do not support a preventive effect in the onset of new allergen sensitizations, in children treated with AIT in comparison with those treated with pharmacotherapy.