A 10-year experience of a novel and safe modified environmental rush immunotherapy protocol

Background Allergen immunotherapy (AIT) is an effective treatment option for allergic rhinitis. Although conventional AIT takes 6 months to reach maintenance dosing, rush AIT accelerates the build-up period and reaches the maintenance dose months earlier. However, accelerated schedules of AIT carry an increased risk of systemic reactions (SR). Objective We aimed to describe a novel 1-day, eight-step modified environmental rush immunotherapy (MERIT) protocol, characteristics of the patients who underwent this therapy, and the safety of this procedure. We also compared distinguishing features of those patients with SRs. Methods We retrospectively analyzed demographic and clinical data of 362 adult patients seen in an outpatient university allergy clinic, from January 2005 to January 2015, and who underwent MERIT protocol treatment for allergic rhinitis. Results In a univariate analysis, the factors significantly associated with SR were lower body mass index (BMI); younger age; a higher number of allergens in the extracts; and the presence of cat, dust mite, and certain weed pollens. In a multivariate analysis, cat, dust mite, and mugwort were significantly associated with SRs. Over the 10-year period, 50 patients experienced SRs (13.81%), with a total number of 68 SRs. Only 4.7% of the SRs occurred on the MERIT day. Most SRs occurred >30 minutes and were mild. Our MERIT protocol continuation rate for all the patients was 49.2% and did not seem to be influenced by having an SR versus no SR. Conclusion We present a modified rush AIT protocol that seems to be effective and safe. Most patients tolerated therapy, and only a minority of patients developed SRs, which generally were mild. We identified novel risk factors for SRs that may help determine optimal dosing to decrease the risk of SRs. Ultimately, future studies will be needed to compare the safety of our MERIT protocol with traditional AIT.