House dust mite allergies, how do we treat?

Published Online October 24, 2013

House dust mites produce a wide range of indoor airborne allergens, which in turn have a well-established causal role in persistent allergic respiratory diseases such as allergic rhinitis and allergic asthma. These conditions can be treated with allergen immunotherapy, i.e., desensitization with purified formulations of the incriminated allergen, so that the patient reacts less intensively upon exposure to environmental levels of that allergen. Although double-blind, placebo-controlled randomized clinical trials have shown that house dust mite allergen immunotherapy can be effective in relieving symptoms and decreasing medication use, the reported magnitude of its effects is small to moderate and varies greatly from one trial to another.

In a recent article published in The Journal of Allergy & Clinical Immunology (JACI), Calderon et al. performed an evidence-based medicine review of house dust mite allergen immunotherapy modalities for allergic rhinitis and allergic asthma. To exclude poor-quality evidence, the researchers considered only double-blind, placebo-controlled randomized clinical trials of currently available commercial formulations administered either subcutaneously or sublingually. From each selected trial, the researchers extracted data on crucial parameters such as the study design, patient screening methods, the number of patients included in the trial, the patients' disease severity on inclusion, the doses of allergen administered, the treatment duration, and the criteria used to judge efficacy.

Calderon and colleagues found that even when considering supposedly high-quality clinical trials, there were marked inter-study differences in all of the above-mentioned parameters – even including the dose and duration of treatment. Although the safety profile of house dust mite allergen immunotherapy appeared to be good, few studies reported on product safety in detail. These observed methodological shortcomings prompted the researchers to make the following suggestions for the clinical testing of properly standardized house dust mite allergen formulations, including (i) perform well-designed multicenter trials, with sufficient statistical power, (ii) consider disease severity, disease control and/or allergen challenge scores when including patients in trials, (iii) perform dose-ranging studies in adults and (separately) in children, (iv) run trials that last for at least one year, and (v) assess quality of life with disease-specific tools control. On a positive note, the authors conclude their review by writing that although much work remains to be done, this field is moving ahead. New, high-quality vaccines are currently being tested in the clinic and should soon be available for registration.

The Journal of Allergy and Clinical Immunology (JACI) is the official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.

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