Background: The clinical efficacy and safety of a six-grass pollen allergoid has been studied. The advent of more exacting clinical guidelines and a better appreciation of the possible mechanisms of treatment prompted this reappraisal.
Methods: A 2-year double-blind multicentre placebo-controlled phase 3 clinical trial was undertaken in 154 patients suffering symptoms of rhinoconjunctivitis with or without asthma (GINA I or II). Therapy comprised two consecutive preseasonal short-courses of subcutaneous injections using a grass pollen allergoid adsorbed to aluminium hydroxide.
Results: A combined symptom and medication score (SMS) was used as the primary end-point for clinical efficacy. SMS from the first year showed a significant difference of 26.6% between the two study groups (P = 0.026) and this was improved after the second year when there was a 48.4% difference in SMS between active and placebo treatment in favour of the allergoid (P = 0.018). Highly significant increases in grass pollen allergen-specific IgG1 and IgG4 antibody concentrations were measured in association with active treatment. Allergen tolerance was increased as judged by a conjunctival provocation test and significant improvements in quality of life were documented using a standardized questionnaire. The allergoid was well tolerated.
Conclusions: The grass pollen allergoid was shown to be safe and clinically efficacious in the management of hay fever with or without asthma (GINA I or II).