Preventive symptomatic immunotherapy versus placebo in seasonal rhinitis due to grasses in children and to Parietaria in adult patients.

Background: EPD is the only preventive symptomatic immunotherapy available on the market and approved by competent bodies. Recent double-blind placebo controlled (DBPC) studies have demonstrated its efficacy in seasonal and perennial rhinitis. The aim of the study was to confirm the efficacy and safety of a single dose of immunotherapy administered six-eight weeks before the pollen season.

Methods: Two simultaneous DBPC trials were carried out. The first consisted of 20 children with grass-pollen seasonal rhinitis (Bollate-Milano, Italy) and the second included 30 adult patients with Parietaria-pollen seasonal rhinitis (Genova, Italy). EPD was administered only to the active groups.

Results: A significant difference in favour of the active treatment groups was seen in oral antihistamine use (p < 0.05) during the peak pollen seasons. Throughout the pollen seasons, rhinoconjunctivitis scores for the two groups in both studies presented no significant difference, even if the values were lower in the active groups.

Conclusions: The oral antihistamine reduction, observed in the active groups during the seasonal period, supports the efficacy of this treatment, although a significant improvement in the rhinoconjunctivitis symptoms was not observed, probably due to the use of oral antihistamine in the placebo groups. The overall profile of the EPD was good. It could be particularly suited for short term therapy to prevent seasonal symptoms in allergic patients.