Allergen avoidance in the treatment of asthma: Problems with the meta-analyses

doi:10.1016/j.jaci.2008.07.045

Journal of Allergy and Clinical Immunology

Volume 122, Issue 4, October 2008, Pages 694-696

https://doi.org/10.1016/j.jaci.2008.07.045 Get rights and content

Decreasing exposure to indoor allergens has been studied extensively and is a well accepted part of the treatment for allergic disease. The 2007 revision of the evidence-based guidelines recommends allergen avoidance as part of the management of asthma. In contrast, a recent meta-analysis concluded that dust mite avoidance is “of no use” in the treatment of asthma. There are obvious sources of bias that could have influenced the evaluation of published trials either by the guideline panel or by the group conducting the meta-analysis. An important issue is whether meta-analysis is a valid method of evaluating studies such as those on dust mite avoidance that are highly variable. Reading the published series of 4 meta-analyses on this subject from the Cochrane Library suggests that decisions about which trials to include can have a major effect on the outcome. The process of meta-analysis may also have other potential conflicts. The recent meta-analysis on dust mite avoidance appears to be seriously flawed because of the decisions about inclusion and exclusion as well as the way in which studies were evaluated. The conclusion is that the criticisms of the recommendations in the 2007 guidelines were not well founded.

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Cited by (86)

Allergenic and chemical pollutants of indoor environments and asthma: Characterization, assessment and eviction
2023, Revue des Maladies Respiratoires
L’environnement d’un patient asthmatique peut contenir de nombreuses sources de polluants qui dégradent la qualité de l’air intérieur et présentent des conséquences importantes sur l’apparition ou le contrôle de l’asthme. L’évaluation et l’amélioration de la qualité de l’air intérieur doivent prendre une place importante dans la consultation en pneumologie et en allergologie. Caractériser l’environnement d’un asthmatique implique de rechercher des polluants biologiques avec les allergènes d’acariens, les moisissures et les allergènes relatifs à la présence d’animaux de compagnie. Il est important d’évaluer la pollution chimique représentée par une exposition aux composés organiques volatiles qui sont de plus en plus présente dans nos logements. Le tabagisme actif ou passif doit toujours être recherché et quantifié. L’évaluation de l’environnement est médiée par plusieurs méthodes qui dépendent du polluant recherché mais la place de la méthode immuno-enzymatique par ELISA reste centrale pour les polluants biologiques. Une éviction globale de tous les polluants de l’environnement intérieur est médiée par les conseillères en environnement intérieur et permet d’obtenir une évaluation et un bon contrôle de l’air intérieur. Cette méthode utilisée dans une logique de prévention tertiaire permet d’améliorer le contrôle de l’asthme chez les enfants mais aussi chez les adultes.
The environment of an asthmatic patient can contain numerous sources of pollutants that degrade the quality of indoor air and have major repercussions on the occurrence and control of asthma. Assessment and improvement of the quality of indoor air should be assigned a major role in pneumology and allergology consultations. Characterization of an asthmatic's environment entails a search for biological pollutants with mite allergens, mildew, and allergens resulting from the proximity of pets. It is important to evaluate the chemical pollution represented by exposure to volatile organic compounds, which are increasingly present in our lodgings. Active or second-hand smoking must in all circumstances be sought out and quantified. Assessment of the environment is mediated by several methods, of which the application depends not only on the pollutant sought out, but also on enzyme-linked immunosorbent assay (ELISA), which has an essential role in quantification of biological pollutants. Attempts at expulsion of the different indoor environment pollutants is mediated by indoor environment advisors, whose efforts are aimed at obtaining reliable evaluation and control of indoor air. Implemented as a form of tertiary prevention, their methods are conducive to improved asthma control, in adults as well as children.
Indoor and Outdoor Allergens and Pollutants
2022, Allergy Essentials
Indoor and outdoor allergen sources contain many allergens, the majority of which are proteinaceous. The most important outdoor allergens include the aeroallergens from pollens of grasses, weeds and trees, the spores and mycelia from various species of fungi, and the venoms and saliva from stinging and biting insects. Indoor aeroallergens are derived primarily from the feces of various arthropods such as house-dust mites and cockroaches, and danders and urine of animals such as pets and rodents present in domestic dwellings. Irrespective of source, phylogenetically related species produce similar spectra of allergens. Except for stinging and biting insects, allergen sensitization and provocation are due to both their propensity to become airborne and their respirability. Although no unifying structural feature determines allergenicity, the biochemistry of allergens is likely to be important, particularly in association with toll-like receptor—activating bacterial cell wall–derived components such as lipopolysaccharide and peptidoglycan. Allergen avoidance can be an effective countermeasure for asthma, perennial rhinitis, and atopic dermatitis/eczema, but compliance and sufficient allergen reduction may be difficult to achieve. Air pollution may occur both indoors and outdoors and exacerbate asthma symptoms as well as contribute to the development of allergic disease through direct, nonallergic effects or by interactions with allergens per se.
Question 6: What is the use of allergy testing in children with asthma?
2021, Paediatric Respiratory Reviews
Citation Excerpt :
The cost of specific IgE sensitization screening is considerably higher than that of skin prick testing, however, and results are not immediately available. To add precision to diagnosing allergy, the level of sensitization to a specific allergen should be taken into consideration, because the risk of having a symptomatic inhalant allergy increases with higher levels of sIgE [39]. In an adult cohort, approximately 2/3 of patients with slightly elevated specific IgE to house dust mite or cat did not report any symptoms suggestive of a house dust mite or cat dander allergy, compared to over 95% of patients with high level grass pollen IgE levels reporting symptoms in the grass pollen season [39].
Disagreement exists between asthma guidelines on the routine use of allergy testing in the diagnostic work-up of a child with persistent asthma, although the important role of inhalant allergy in the pathophysiology of asthma and allergic rhinitis is undisputed. The usefulness of screening for inhalant allergies in asthma is connected to the efficacy of allergen reduction measures and specific immunotherapy, both of which appear to be more effective in children than in adults. Allergen-specific exposure reduction recommendations are therefore an essential part of childhood asthma management. Such recommendations should be guided by appropriate diagnosis of inhalant allergy, based on a structured allergy history and results of sensitization tests. Specific IgE testing and skin prick testing show comparable results in identifying clinically important sensitizations. Although a therapeutic medication trial can be started pragmatically in children with asthma without diagnosing their inhalant allergy, we recommend making or excluding an accurate diagnosis of inhalant allergy.
Cluster analysis of indoor environmental factors associated with symptoms of mite allergy
2019, Annals of Allergy, Asthma and Immunology
Citation Excerpt :
This recommendation has been discussed in other studies3,4 based on a meta-analysis by Gøtzsche.5,6 However, the most recent meta-analysis did not include 2 multifaceted allergen-reduction studies, as pointed out by several authors.7,8 In the 4 studies9–12 that were not included in the meta-analysis by Gøtzsche,5,6 global allergen reduction was demonstrated to be effective for reducing allergen exposure and for improving clinical outcomes of children with moderate to severe asthma.
The clinical efficacy of controlling environmental allergens as a component of allergic asthma treatment remains controversial. Multifaceted allergen reductions appeared to be the most efficient methods. However, they require home visits with indoor technicians.
To examine the characteristics of indoor environments that might be related to symptoms of children and adult patients with mite allergic rhinitis and/or asthma.
We included 315 patients allergic to house dust mites with rhinitis and/or asthma who had been visited at home by 2 medical indoor environment counselors (MIECs) from the Strasbourg University Hospital between January 2007 and June 2015. In a cluster analysis, we analyzed 42 characteristics of respiratory symptoms, dwelling characteristics, and indoor pollutants in this population.
Three clusters were defined among the patients. Cluster 1 included 55 patients, all with rhinitis, 32% with asthma, and all living in an urban area. Clusters 2 and 3 included 86 and 174 patients, respectively. The important factors in these 2 clusters were asthma incidence and exposure to different indoor pollutants, such as indoor perfumes, cleaning products, and tobacco smoke.
Our results underlined the variability of indoor environments and the importance of MIEC home visits to investigate individual patient environments and propose an appropriate avoidance management plan. Our results showed that sensitization to mite and exposure to indoor chemical pollutants were associated with severe asthma.
Asthma, rhinitis, and nasal polyp multimorbidities
2019, Archivos de Bronconeumologia
El objetivo de esta revisión es facilitar al neumólogo el manejo de las enfermedades de la vía respiratoria superior ligadas a la vía respiratoria inferior, especialmente al asma, unidas por una epidemiología, una clínica y un mecanismo inflamatorio comunes e interrelacionados.
El documento recoge las definiciones de los diferentes fenotipos nasosinusales ligados al asma: rinitis alérgica o no alérgica y rinosinusitis crónica con o sin pólipos nasales. Asimismo se recogen los criterios diagnósticos y su nivel de gravedad.
Se dedica especial atención a los dos síndromes principales asociados al asma: 1) rinitis alérgica, la patología más frecuente, y 2) rinosinusitis crónica con pólipos nasales, la patología más ligada al asma grave.
En síntesis, en el manejo del asma debe valorarse siempre la vía respiratoria superior con la finalidad de un diagnóstico unificado y un tratamiento integral de la vía respiratoria única.
The aim of this review is to assist pulmonologists in the management of diseases involving both the upper and lower respiratory tract that are linked by a common, interrelated epidemiology, clinical signs and symptoms, and inflammatory mechanism − asthma, in particular.
The document discusses the definitions of the various sinonasal phenotypes associated with asthma: allergic and non-allergic rhinitis and chronic rhinosinusitis with or without nasal polyps. Diagnostic criteria and severity levels are also listed.
Particular attention has been given to the 2 main syndromes associated with asthma: (i) allergic rhinitis, the most common, and (ii) chronic rhinosinusitis with nasal polyps, the disease most closely associated with severe asthma.
To summarize, the upper respiratory tract should always be evaluated in order to achieve a single diagnosis and comprehensive treatment of the “united airway”.
46 - Severe Asthma
2019, Kendig's Disorders of the Respiratory Tract in Children
Most pediatric asthma is easily treated with low-dose inhaled corticosteroids, occasionally combined with a long-acting bronchodilator, provided the medications are administered regularly and correctly. If the child does not respond to treatment, rather than escalating treatment uncritically, a detailed, protocolized assessment is mandatory. This should include a review of the diagnosis and assessment of the presence or otherwise of any extrapulmonary comorbidities, such as obesity, exercise-induced laryngeal obstruction and lifestyle and social factors, such as adherence, perhaps the most important cause of “treatment resistant asthma,” and allergen and tobacco exposure; this enables successful management of 90% of referrals with apparent severe asthma. For the rest, bronchoscopic assessment of airway pathology is advisable, combined with a parenteral steroid trial, to deconstruct airway pathology by determining the presence and nature of any inflammation and whether there is fixed airflow obstruction. If inflammation is present, it is eosinophilic not neutrophilic but signature T-helper cell cytokines are difficult to detect, suggesting alternative pathways are important. There is no agreed upon pediatric definition of steroid responsiveness, and we advocate a multidomain approach. Other than for omalizumab, treatments for steroid-resistant asthma have no evidence base in children. The child with recurrent asthma attacks is particularly difficult to manage and is at high risk of further attacks and death from asthma. In summary, therapy-resistant asthma is rare but a really difficult problem when present. Most apparent therapy-resistant asthma can be successfully treated by optimizing basic management, especially ensuring adherence to standard therapy.

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: Disclosure of potential conflict of interest: T. A. E. Platts-Mills is on the scientific advisory board for Indoor Biotechnologies and receives grant support from Phadia and Bristol Myers Squibb.

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Reviews and feature articleAllergen avoidance in the treatment of asthma: Problems with the meta-analyses

J Allergy Clin Immunol

Lancet

J Allergy Clin Immunol

Lancet

Ann Allergy Asthma Immunol

J Allergy Clin Immunol

J Allergy Clin Immunol

Allergen avoidance to reduce asthma-related morbidity

N Engl J Med

Dust-mite control measures of no use

Lancet

House dust mite control measures for asthma

Cochrane Database Syst Rev

Reviews and feature article
Allergen avoidance in the treatment of asthma: Problems with the meta-analyses