Background The optimal dose (300IR) of a five-grass pollen sublingual immunotherapy tablet in terms of efficacy was previously demonstrated from the first pollen season.
Objective Here, we aim to confirm whether this dose remained optimal during the peak of the pollen season by assessing the efficacy and quality of life data.
Methods A total of 628 subjects with grass pollen rhinoconjunctivitis were randomized in a double-blind, placebo-controlled, multi-centre, pan-European trial. Subjects received once-daily tablets (Stallergenes, Antony, France) of 100IR, 300IR, 500IR or placebo, starting 4 months before and throughout the 2005 grass pollen season. The pollen season was defined as the first day of 3 consecutive days with a grass pollen count above 30 grains/m3 of air, recorded using Hirst-type volumetric pollen traps, to the last day before 3 consecutive days with a pollen count below 30 grains/m3.
Results The grass pollen season lasted an average of 30 days, with a peak of 12 days. The mean treatment duration before the grass pollen season was similar in the four treatment groups (121.4±31.1 to 128.6±15.4 days in the safety population). Both the 300IR and 500IR groups had highly significant improvements in Rhinoconjunctivitis Total Symptom Score (RTSS) vs. placebo at the peak pollen season (P=0.0005 and 0.0014, respectively), which agreed with improvements in RTSS in the primary evaluations. The average RTSS scores were slightly elevated during the peak pollen season in all treatment groups. The overall Rhinoconjunctivitis Quality of Life Questionnaire score confirmed the optimal dosage 300IR at peak (P<0.0001) and at the end (P0.0031) of the pollen season. All doses were well tolerated.
Conclusion At the peak pollen season, the efficacy and quality of life data for both 300IR and 500IR groups was significantly improved vs. the placebo group. These results confirm the conclusions of the primary evaluations and validate the use of 300IR tablets for clinical practice.