An evidence-based analysis of house dust mite allergen immunotherapy: A call for more rigorous clinical studies

Background: According to meta-analyses and reviews, subcutaneous allergen immunotherapy (SCIT) and sublingual allergen immunotherapy (SLIT) are beneficial in patients with allergic rhinitis (AR) and allergic asthma (AA) induced by house dust mites (HDMs). However, the reported effect sizes have varied greatly from one study to another. Objective: We sought to perform an evidence-based medicine assessment of commercially available SCIT and SLIT formulations in patients with HDM-induced AA and HDM-induced AR. Methods: We searched for double-blind, placebo-controlled randomized clinical trials and analyzed study designs, doses, regimens, patient-reported outcomes, safety reporting, and compliance. Results: Forty-four studies met our inclusion criteria. Some studies tested both SLIT and SCIT or scored both AA and AR outcomes; therefore we reviewed 35 treatment arms in patients with AA (20 for SCIT and 15 for SLIT) and 23 treatment arms in patients with AR (7 for SCIT and 16 for SLIT). The treatment duration ranged from 6 weeks to 3 years. For SCIT, the dose of Der p 1 major allergen (when reported) ranged from 7 to 30 mu g for maintenance doses and 60 to 420 mu g for cumulative doses. For SLIT, the doses of Der p 1 (when reported) were 0.8 to 70 mu g for maintenance doses and 60 to 23,695 mu g for cumulative doses. Safety data were often absent or poorly reported. A statistically significant active versus placebo symptom score was observed more frequently for SCIT than for SLIT. Conclusion: There is no consensus on basic treatment parameters (eg, dose and duration) in HDM SCIT and SLIT. There is an urgent need for rigorous, long-term, double-blind, placebo-controlled randomized clinical trials with an efficacy criterion that reflects the particular features of HDM-induced allergic disease.