Background: Sublingual immunotherapy treatment with grass allergen tablets (Grazax) is initiated preseasonally without up-dosing and treatment is continued throughout the entire grass pollen season.
Aims of the study: The influence of the duration of preseasonal treatment on clinical efficacy obtained within the grass pollen season was investigated.
Methods: Data from three randomized, double-blind, placebo-controlled, multi-centre trials with varying preseasonal treatment periods were analysed. In the grass pollen season, symptom and medication score reductions relative to placebo were calculated and correlated with the duration of the preseasonal treatment period.
Results: The analysis was based on data from 934 patients. A significant reduction in seasonal daily rhinoconjunctivitis symptom and medication scores (17%, CI: 1-33% and 23%, CI: 1-47%, P < 0.05) was observed for patients treated with Grazax compared with placebo after approximately 8 weeks of pretreatment. The magnitude of the reductions in rhinoconjunctivitis symptom and medication scores increased with longer duration of preseasonal treatment (P < 0.0001).
Conclusions: Sublingual immunotherapy with Grazax) must be initiated at least 8 weeks prior to the grass pollen season to provide a significant clinical efficacy. A longer preseasonal treatment period (>8 weeks) improves the clinical efficacy (relative to placebo) during the grass pollen season.