The Effect of Extrinsic Factors on Food Allergy

Cambridge University Hospitals NHS Foundation Trust4 个研究点分布在 1 个国家目标入组 100 人开始时间: 2012年10月最近更新: 2015年1月14日

适应症

干预措施

试验速览

阶段: 2 期
发起方: Cambridge University Hospitals NHS Foundation Trust
入组人数: 100
试验地点: 4
主要终点: minimum amount of peanut protein in milligrams which causes an objective clinical reaction during peanut challenges

研究概览研究设计入排标准研究组 & 干预措施结局指标研究者研究点记录与标识符相似试验

研究概览

简要总结

Food allergy is a common problem, affecting 5-8% of the population. Peanut allergy causes reduced quality of life due to the perceived high risk of severe reactions. Patients rely on accurate labeling of both loose and pre-packed foods, but these are often ambiguous and unhelpful. There is a common conception that labeling is 'over-cautious'. Peanut-allergic consumers face increasingly restricted food choices in complying with this advice due, in part, to the proliferation of advisory labels such as 'may contain peanuts'. This contributes to the reduces quality of life of affected individuals.

For industry to provide more accurate and helpful labeling, certain characteristics of the food-allergic population need to be defined. Firstly, the minimum 'eliciting dose' for the population has been estimated by studying large groups of peanut allergic patients who are challenged with peanut ingestion in increasing amounts. From these, an eliciting dose that provokes a reaction in 10% of the food-allergic population has been estimated at between six and 14mg of peanut protein.

Translation of population eliciting doses (ED) into acceptable levels of allergen contamination for the population requires consideration of a 'safety factor'- to account for individual variability in dose threshold and severity. Data suggest such variability depends in part on extrinsic factors (exercise and sleep restriction). Each factor may have a different effect in scale and direction. The investigators are proposing a cross-over trial with 85 peanut-allergic adults who will each undergoing a baseline peanut challenge followed by repeat challenges with extrinsic factors applied, in random order (repeat baseline, +exercise and +sleep restriction). These data will further define ED for the UK population and a safety factor derived from shift in threshold, to inform industry and protect the allergic population.

详细描述

N=100 subjects will undergo a baseline challenge to peanut without exacerbating extrinsic factors. These initial baseline challenges will be performed when asthma is well controlled (validated by normal spirometry values), the subject is rested and there is no evidence of viral illness (clinical history and examination). A two-day double blind placebo controlled peanut challenge (DBPCPC) will be performed. Subjects receive either all placebo doses or all active doses on one of two days. Each day consists of all eight doses separated by 20 minute intervals (3microg to 1g). The active doses are hidden in a carrier which has been assessed for blinding efficacy. Subjective and objective dose threshold and severity score for challenge outcome will be recorded. Subjects will receive detailed written and verbal advice to avoid peanut until the next challenge. All subjects will be asked to carry oral antihistamines and injectable adrenaline.

All participants who have a clinical reaction during the initial baseline DBPCFC will be randomized to one of 6 balanced cross over intervention sequences from a Latin square design. Each group rotates through three further challenges in a different order: control (no extrinsic factor), exercise and sleep restriction.

Control challenge

Subjects must not have had any accidental reaction to peanut in the previous three months. This challenge will be performed when asthma is well controlled (validated by spirometry normal values), the subjects are rested (sleep diary for preceding week will be examined) and there is no viral illness (clinical history and examination). A peanut challenge will be performed (identically to the initial baseline DBPCFC). Dose threshold and severity score for challenge outcome will be recorded. 2. Exercise challenge Subjects undergo a repeat challenge to peanut with exercise as an extrinsic factor, a minimum of three months after the previous challenge. Subjects must not have had any accidental reaction to peanut in the previous three months. This challenge will be performed when asthma is well controlled (validated by spirometry normal values for the individual and clinical history), the subjects are rested, and there is no viral illness.

The challenge will be double blind and placebo controlled. The challenge will take place on two occasions, on one day all four doses will contain placebo only, on the second all four doses will be active (peanut). The subjects will undergo an identical exercise protocol on both days.

研究设计

研究类型: Interventional
分配方式: Randomized
干预模型: Crossover
盲法: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)

入排标准

年龄范围: 18 Years 至 45 Years（Adult）
性别: All
接受健康志愿者: 否

入选标准

•Written informed consent must be obtained before any assessment is performed.
•Male and female subject who are 18-45 years of age at the time of study entry (Visit 1) who have a diagnosis of acute peanut allergy as manifested by urticaria, angioedema or respiratory/gastrointestinal tract symptoms, with acute onset of symptoms after ingestion (up to 2h).
•A positive peanut DBPCFC at baseline (Visit 1). This outcome is defined as the onset of objective allergic events after ingestion of peanut protein but not to the placebo. Eligibility to the DBPCFC requires fulfillment of all other eligibility criteria at visit
•Subjects must be able to comply with the study procedures.

排除标准

未提供