Objective: To assess the efficacy of enzyme potentiated desensitisation in the treatment of severe summer hay fever poorly controlled by pharmacotherapy.
Design: Double blind randomised placebo controlled parallel group study.
Setting: Hospital in Hampshire.
Participants: 183 participants aged between 18 and 64 with a history of severe summer hay fever for at least two years; all were skin prick test positive to timothy grass pollen. 90 randomised to active treatment; 93 randomised to placebo.
Interventions: Active treatment: two injections of enzyme potentiated desensitisation, given between eight and 11 weeks apart, each comprising 200 Fishman units of beta glucuronidase, 50 pg 1,3-cyclohexanediol, 50 ng protamine sulphate, and a mixed inhaled allergen extract (pollen mixes for trees, grasses, and weeds; allergenic fungal spores; cat and dog danders; dust and storage mites) in a total volume of 0.05 ml of buffered saline. Placebo: two injections of 0.05 ml buffered saline solution.
Main outcome measures: Proportion of problem-free days; global rhinoconjunctivitis quality of life scores assessed weekly during pollen season.
Results: The active treatment group and the placebo group did not differ in the proportion of problem-free days, quality of life scores, symptom severity scores, change in quantitative skin prick provocation threshold, or change in conjunctival provocation threshold. No clinically significant adverse reactions occurred.
Conclusions: Enzyme potentiated desensitisation showed no treatment effect in this study.