Sublingual allergen therapy of house dust mite allergy provides sustained relief of symptoms after treatment cessation. Margitta Worm, MD, of Charité University Clinic in Berlin, and colleagues had previously shown in a randomized, double-blind, placebo-controlled trial the safety and efficacy of two doses of sublingual allergen tablets administered for 12 months to adults with house dust mite-related allergic rhinitis.
In this study they followed the patients for 12 months after therapy cessation. Of the 509 patients randomized, 412 were followed for the full two years (500 IR, n=132; 300 IR, n=134; placebo, n=146). The investigators assessed efficacy using the Average Adjusted Symptom Score (AAdSS), an average of the daily score based on the severity of sneezing, rhinorrhea, nasal pruritus, and nasal congestion, using a 0-12 point scale.
Twelve months after treatment stopped, both dosage groups showed continuing significant improvement in symptoms compared to the placebo group. The 500 IR group had a 19.1% lower AAdSS score vs placebo (P=0.021), and the 300 IR group had a 17.0% improvement (P=0.034). There was no statistically significant difference between the scores of the two active treatment groups.
The AAdSS for the active treatment groups were also significantly reduced at the autumn peak of house dust mites, occurring eight months after treatment cessation (500 IR, -20.9%, P=0.0079; 300 IR, -25.5%, P=0.0011).