Background: There is ample evidence to support the efficacy of sublingual immunotherapy (SLIT) on allergic rhinitis, while there is less solid data regarding asthma. We evaluated the effects of a high dose birch SLIT on birch-induced rhinitis and asthma in a controlled study.
Methods: This double-blind, placebo-controlled, randomised, single centre trial on SLIT with birch pollen allergen extract (Stallergenes, Antony, France) included 24 patients presenting severe rhinitis and slight to moderate asthma, 14 actively and 10 placebo treated. SLIT was performed by a pre-coseasonal protocol, and was repeated for 2 years. The study plan included a selection visit, a visit at the start of the first and the second treatment cycle, a follow-up visit after 1-3 months from the start of each cycle, and a final visit at the end of each yearly cycle.
Results: A significant decrease (p < 0.05) in rhinorrhoea and nasal obstruction occurred in actively treated patients. The median number of days with asthma at visit 3 was 10 (0-27) in the active (SLIT) group and 13 (0-29) in the placebo group. The median number of days with asthma at visit 6 was 2 (0-6) in the SLIT group and 7 (0-15) in the placebo group (p < 0.05 between groups). A stepdown of asthma occurred in 77% of actively treated vs. none of placebo treated patients (p = 0.05). No severe adverse events were observed.
Conclusions: This pilot study suggests that SLIT with high dose birch extract may be able to step down seasonal pollen-induced asthma after prolonged treatment.