Background: The optimal dose of five-grass pollen sublingual tablet immunotherapy (SLIT) was established recently by the primary criteria Rhinoconjunctivitis Total Symptom Score (RTSS) from the first treatment season. Secondary and exploratory criteria, such as RTSS at peak pollen season, exploratory combined symptom and rescue medication use score, quality of life and immunological markers are calculated and described in this analysis.
Methods: Six hundred and twenty-eight patients with grass pollen rhinoconjunctivitis (≥2 years duration) were randomized in a double-blind, placebo-controlled trial conducted in Europe. Patients received once-daily SLIT (Stallergenes, Antony, France) of 100IR, 300IR, 500IR or placebo, starting 4 months before grass pollen season and throughout the 2005 season. Patients were instructed to take rescue medication only if symptoms were severe and record symptom severity on using the RTSS.
Results: Both 300IR and 500IR doses significantly reduced mean RTSS at pollen peak (P = 0.0005 and P = 0.0014, respectively) and the exploratory combined score (P = 0.0001 and P = 0.0026, respectively) compared with placebo. Compared with patients in the placebo group, those who were taking the 300IR and 500IR doses reported significantly improved quality of life using the mean Rhinoconjunctivitis Quality of Life Questionnaire scores during the peak of the pollen season (P < 0.0001) and at the end of the pollen season (P = 0.0031 and P ≤ 0.0001, respectively). Specific immunoglobulin G4 increased significantly depending on the SLIT dose (P < 0.0001).
Conclusions: All secondary efficacy criteria, including efficacy at pollen peak, combined score, quality of life and immunological changes, indicate that 300IR tablets represent the optimal dose and suggest it is appropriate for use in clinical practice.