Efficacy of grass pollen sublingual immunotherapy for three consecutive seasons and after cessation of treatment: the ECRIT study.

Background: Data supporting a carry-over effect with sublingual immunotherapy (SLIT) are scarce. This randomized, double-blind, placebo-controlled study evaluated the efficacy, carry-over effect and safety of grass pollen SLIT using co-seasonal treatment.
Methods: Patients (7.9-64.7 years) with grass pollen allergy received ultra-rush titration with increasing doses (30, 90, 150 and 300 IR) of a 5-grass pollen mixture every 20 min at the start of the pollen seasons, followed by 300 IR daily until the end of the pollen seasons. A baseline season (no SLIT) was followed by three consecutive treatment seasons and one follow-up season. Symptoms, medication and adverse events were documented and specific immunoglobulin (Ig)E and IgG(4) measured.
Results: Data were analysed for 183 of the 213 randomized patients. Mean treatment duration varied between seasons (81.8-92.7 days). Combined scores (symptoms and medication) improved progressively across treatment seasons (up to 44.7% improvement for SLIT compared with baseline) and fluctuated between -11.3% and -14.8% for placebo (P < 0.05). Similar changes were observed for symptom scores, with a successive decrease of 39.7% (SLIT) and fluctuations between +13.6% and -1.51% for placebo (P < 0.05). Combined score (P = 0.0508) and symptom score improvements (P = 0.0144) with SLIT continued during follow up. Increases in specific IgG(4) observed in the first season were sustained for SLIT vs placebo throughout treatment (P = 0.0001). Titration and daily SLIT were well tolerated. No serious systemic or anaphylactic reactions were reported.
Conclusions: Seasonal SLIT with ultra-rush titration is well tolerated and effective from the first treatment season onwards. These data indicate a carry-over effect of seasonal SLIT.