The allergen-specificity of allergen immunotherapy - doubt no more.

The ARIA-GA2LEN collaboration published a guide for the design and evaluation of randomised controlled trials of allergen immunotherapy for allergic rhinitis. Several problems in were identified. For example, the severity/persistence of seasonal symptoms in subjects during allergen immunotherapy was noted to be much lower than in trials of pharmacotherapy. The drop-out rates were higher. Seasonal pollen counts varied markedly between study centres and year-on-year during long-term trials thereby confounding the ability to detect treatment effects during 'low' pollen seasons. Placebo unmasking occurred due to the local side effects of allergen immunotherapy in actively treated participants. This article is protected by copyright. All rights reserved.