Safety of Bronchial Allergen Challenge and Predictors for Positive Reaction.
Condition: House Dust Mite Allergy; Bronchial Hyperresponsiveness
MeSH terms: Dust Mite Allergy; Bronchial Hyperreactivity
Study type: Interventional

Summary: 
      The present study is aimed to evaluate a bronchial allergen challenge with house dust mite
      and alternaria. Firstly, the years 2005, 2006, 2007, 2008 and 2009 will be retrospectively
      reviewed. Secondly, in 2010-2013, in the prospective part of the study the patients will
      undergo the bronchial allergen challenge to examine safety of the bronchial allergen
      challenge and change of allergen specific bronchial hyperreactivity before and after allergen
      specific immunotherapy.
    

Detailed description: 
      Specific bronchial allergen challenge is an established tool in clinical practice and
      research, supporting the understanding of pathophysiology of allergic asthma, and analysing
      the efficacy of new therapies. However, in preschool age there is only a few data about
      specific bronchial allergen challenges. Douglas (1) evaluated the predictors of positive
      response to bronchial allergic challenges with house dust mite and grass pollen in twelve
      5-to 6-year-old atopic children. The most statistically significant predictors were the
      extent of atopy proven by skin prick testing, specific IgE, symptoms of asthma, and
      persistent atopic eczema. However, the number of patients was small. Therefore, more research
      is needed to confirm these findings. Further, the nonspecific bronchial hyperreactivity was
      found to have a high positive predictive value for positive reactions (2). To our best
      knowledge, this aspect is not investigated in children.

      This study examines retro- and prospectively the safety of a bronchial allergic challenge
      with house dust mite, grass pollen and alternaria. The retrospective part will evaluate the
      associations of early allergic reaction, skin prick testing, specific IgE, measurement of
      exhaled NO, spirometry/IOS and bronchial methacholine challenge. The prospective part will
      measure the early allergic reaction (EAR) and focus on the late allergic reaction (LAR)and
      examine the change of allergen specific bronchial hyperreactivity before and after allergen
      specific immunotherapy. The study consists of two visits in the first year of the study and
      one follow-up visit per year. At first visit, all the patients undergo skin prick testing,
      measurement of exhaled NO, spirometry/IOS and bronchial methacholine challenge. At next visit
      specific bronchial allergen challenge will be performed and a blood sample will be taken.
      After that, each patient will measure hourly the peak flow during the next 10-hours. This
      procedure will be repeated after the first and second year of allergen specific
      immunotherapy. The safety issue of the study will be published separately. The change of the
      allergen specific bronchial hyperreactivity will be evaluated after every year of the study.
    

Intervention name(s): house dust mite and alternaria allergen bronchial challenge
Intervention type(s): Biological
Intervention description(s): 2 ml of saline-dissolved lyophylised house dust mite or alternaria in concentration 5000 standard biological units (SBU/ml) The challenge is the only intervention. dosed in 6 steps of 5, 10, 20, 40, 80, and 160 SBU. 10 minutes after each step up a spirometry will be performed the challenge will be stopped in case of a ≥ 20% decrease from baseline in FEV1 (PD20) and 0,2 mg Salbutamol will be given.
Other intervention name(s): Lyophylised allergen (Allergopharma, Rheinbeck, Germany)
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Diagnostic
Keywords: EAR; LAR; BHR; house dust mite; alternaria