Fast Onset of Action of Sublingual Immunotherapy in House Dust Mite-Induced Allergic Rhinitis: A Multicenter, Randomized, Double-Blind, Placebo-Controlled Trial

Objectives/Hypothesis: To investigate how quickly an allergic rhinitis (AR) patients' symptoms will improve with sublingual immunotherapy (SLIT). Study Design: Double-blind placebo study. Methods: This is a multicenter, randomized, double-blind, placebo-controlled study of SLIT used to treat house dust mite-induced AR. A total of 120 AR patients, aged 4 to 60 years, were treated for 6 months and randomized into two groups: 1) SLIT with Dermatophagoides pteronyssinus (D. p.) and Dermatophagoides farina (D.f.) extract (n = 60); and 2) matched placebo controls (n = 60). Symptom, medications received, and a visual analog scale score were recorded during the whole study. Serum-specific IgE and IgG4 to D. p. and D. f. were assessed before and after the treatment. Results: Eighty-five patients (70.8%) completed the study. Twelve patients (20%) chose to withdraw from the SLIT group, but none because of serious adverse effects. The total symptom and visual analog scores VAS in the SLIT group decreased significantly when compared to the placebo controls (P < 0.05) after week 14, as well as for the significant (P < 0.05) improvement of all individual AR symptoms in the SLIT group (e. g., sneezing, nasal discharge, itching, and nasal obstruction) after week 22. There was a significant (P < 0.05) increase of IgG4 to both D. f. and D. p. in the SLIT, but not in the placebo group after treatment. Conclusion: SLIT with a mixture of D. f. and D. p. extract is an effective and safe treatment for patients with house dust mite-induced AR. Its onset of action can be observed as early as 14 weeks after treatment.