Statistical issues in clinical trials that involve the double-blind, placebo-controlled food challenge
ABSTRACT The double-blind, placebo-controlled food challenge is a rigorous tool that has become popular for evaluating adverse reactions to foods. The standard use of the double-blind, placebo-controlled food challenge has been to document food allergies for individual patients, but it recently has been gaining acceptance as a procedure for investigating the effectiveness of therapies to prevent/minimize food-induced anaphylaxis. The purpose of this study was to describe the statistical design and analysis issues for clinical trials that use the double-blind, placebo-controlled food challenge in measuring sensitivity to food allergens. Nonparametric tests for within-group and between-group comparisons are described, as well as a discrete-time survival analysis. The statistical methods are applied to simulated data from a clinical trial that compares control therapy and experimental therapy groups. The results indicate that the experimental therapy is significantly better than control in improving the tolerance to peanut flour in patients with peanut allergy. Although simple nonparametric tests for within-group and between-group comparisons are easy to apply, a discrete-time survival analysis provides the best approach because of its flexibility in accounting for important independent variables (regressors) and longitudinal data. Statistical software packages can be adapted to perform such analyses.
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ABSTRACT: The realization of the TPO begin with a precise analysis from criteria ensuring the safety from the child. The paper specify the prerequisites (place of realization, venous access, environment, food preparation), the methodology of the OFC (open, simple or double blind manner) and the management of a reaction occurring during the OFC.
Article: Food allergies and food intolerances[Show abstract] [Hide abstract]
ABSTRACT: Adverse reactions to foods, aside from those considered toxic, are caused by a particular individual intolerance towards commonly tolerated foods. Intolerance derived from an immunological mechanism is referred to as Food Allergy, the non-immunological form is called Food Intolerance. IgE-mediated food allergy is the most common and dangerous type of adverse food reaction. It is initiated by an impairment of normal Oral Tolerance to food in predisposed individuals (atopic). Food allergy produces respiratory, gastrointestinal, cutaneous and cardiovascular symptoms but often generalized, life-threatening symptoms manifest at a rapid rate-anaphylactic shock. Diagnosis is made using medical history and cutaneous and serological tests but to obtain final confirmation a Double Blind Controlled Food Challenge must be performed. Food intolerances are principally caused by enzymatic defects in the digestive system, as is the case with lactose intolerance, but may also result from pharmacological effects of vasoactive amines present in foods (e.g. Histamine). Prevention and treatment are based on the avoidance of the culprit food.Baillière' s Best Practice and Research in Clinical Gastroenterology 02/2006; 20(3):467-83. DOI:10.1016/j.bpg.2005.11.010 · 3.28 Impact Factor
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ABSTRACT: Intramuscular adrenaline is the treatment of choice for food-related anaphylactic reactions. Although auto-injectable adrenaline devices are routinely prescribed for patients at risk of serious reactions, previous studies have shown that only one-third to one and a half of patients or their carers are able to properly use these devices. The aim of this study was to determine which factors are most strongly associated with the effective use of these devices. A 122 children with food allergies who had previously been prescribed EpiPens and were attending a single specialist pediatric allergy center in the UK. were studied prospectively. A 69% of parents were unable to use the EpiPen, did not have it available, or did not know when it should be administered. A prior practical demonstration was associated with a 4-5 fold greater chance that parents would be able to use the device (p < 0.005). Prior consultation with an allergy specialist rather than a general physician, and parents who independently sought additional information from the national self-help allergy organization were also four to six times more likely to be competent with these devices (p < 0.005). The study clearly shows that for EpiPens to be used safely and effectively it is essential to educate the carer at the time the device is prescribed.Pediatric Allergy and Immunology 05/2006; 17(3):227-9. DOI:10.1111/j.1399-3038.2006.00392.x · 3.86 Impact Factor