Control of environmental allergens as a therapeutic approach (original) (raw)

The role of environmental allergen control in the management of asthma

World Allergy Organization Journal, 2022

Allergen exposure may exacerbate asthma symptoms in sensitized patients. Allergen reduction or avoidance measures have been widely utilized; however, there is ongoing controversy on the effectiveness of specific allergen control measures in the management of children with asthma. Often, allergen avoidance strategies are not recommended by guidelines because they can be complex or burdensome, although individual patients may benefit. Here we explore the potential for intervention against exposure to the major allergens implicated in asthma (ie, house dust mites, indoor molds, rodents, cockroaches, furry pets, and outdoor molds and pollens), and subsequent effects on asthma symptoms. We critically assess the available evidence regarding the clinical benefits of specific environmental control measures for each allergen. Finally, we underscore the need for standardized and multifaceted approaches in research and real-life settings, which would result in the identification of more personalized and beneficial prevention strategies.

Clinical trials of allergen avoidance in established asthma

Journal of Allergy and Clinical Immunology, 2001

In its review of asthma management guidelines in 1997, the National Asthma Education and Prevention Program expert panel expressed a belief that available data justified a recommendation that all patients with persistent asthma be evaluated for allergy and that allergen avoidance be included in their management when appropriate. 1 The panel had a surprisingly small number of published reports to consider; in contrast, there were hundreds of randomized, controlled clinical trials that support the use of pharmacologic treatment. In fact, a meta-analysis published just a year later found only 27 studies and concluded that the evidence suggested that environmental control measures had no effect on established asthma. 2 These conclusions have been challenged because the meta-analysis included a number of trials with ineffective mite avoidance and used criteria that excluded 2 trials with a striking effect on both exposure and disease activity. 3 The early clinical trials were conducted before we knew enough about the basic elements of mite allergen avoidance. We now know that bedding is the most important route of exposure; installation of mattress and pillow cases, together with frequent laundering of the bedding and decreased humidity, can reduce exposure sufficiently to decrease asthma morbidity. 4-6 We also know that acaracides are minimally effective in reducing house dust mite allergen in carpeting 5,6 ; interventions that included acaracide treatment of carpeting have not affected the outcomes in clinical trials. 7,8 At this point, we have less understanding of how to reduce cockroach, cat, dog, and mold allergen exposure, and the impression remains that allergen avoidance in established asthma has a minor effect in comparison with pharmacotherapy. The article by Carter et al 9 in this month's issue of the Journal represents an important step. Not only is it one of the first clinical trials to deal with cockroach allergen avoidance; it is the first to examine the effect of combined intervention for dust mite and cockroach in an inner-city population exposed and sensitized to both allergens. Although the authors concluded that the measures tested (mattress and pillow encasings, pesticide bait stations, and cleaning

Allergen avoidance in the treatment of asthma and atopic disorders

Thorax, 1998

The majority of asthmatic patients are atopic humidity is too low to support mite popu--that is, they have IgE mediated sensitivity lations. Mite sensitive asthmatic children had to common inhalant allergens. Exposure and a progressive reduction in non-specific BHR sensitisation to allergens from the house dust when taken from their homes in Holland mite is established as an important risk factor to the mite-free environment of Davos, for asthma in most parts of the world. 1-24 In Switzerland. 38 39 Similarly, a progressive readdition, several recent studies have provided duction in asthma symptoms occurred in chilevidence of the importance of exposure to other dren admitted to the residential home at indoor allergens, particularly those from Misurina (altitude 1756 m). 40 Further studies cats, dogs, and cockroaches. [25] The rate of from Misurina reported a significant decrease sensitisation to mites is directly related to expoin mite allergen-induced basophil histamine sure, 30 whilst conversion from sensitisation to release, mite-specific serum IgE level, and non-sensitisation may occur in indoor enmethacholine BHR with reversal of this trend vironments with low allergen levels. after 15 days of allergen re-exposure at sea The severity of asthma is also related to level. 41 Peroni et al found a significant reduction allergen exposure. 32-35 Objective indices of in total and mite-specific serum IgE and allerasthma severity such as bronchial hypergen-induced BHR after three and nine months reactivity (BHR), forced expiratory volume in at Misurina. These results suggest that avoidone second (FEV 1 ), and variability in peak ance of mite allergen leads to a decrease in expiratory flow rate (PEFR) in patients sensairway inflammation with consequent imitised to dust mites correlate with the level of provement in non-specific BHR and sympmite allergens in their beds. 32 Peat et al found toms, and that re-exposure results in a rapid a similar prevalence of sensitivity to mites in relapse. The high altitude studies were not children living in areas with two different levels controlled and there is a possibility that avoidof exposure to mites but BHR was more severe ance of other domestic factors such as exposure in sensitised children living in the area with the to pets or environmental tobacco smoke conhighest mite levels.

Allergen avoidance in the secondary and tertiary prevention of allergic diseases: does it work?

Primary Care Respiratory Journal, 2006

Although allergen avoidance is widely recommended as part of a secondary and tertiary prevention strategy for allergic diseases, a clear-cut demonstration of its effectiveness is still lacking. Ongoing observational secondary prevention cohorts show that sensitisation to mite can be prevented in the short term by allergen avoidance measures, but further follow-up of these children is needed to show if this effect can be sustained, as well as to ascertain its impact on allergic disease. More well-designed trials are still required before we can give any conclusive advice to our patients. Considering the management of allergy, current evidence suggests that interventions in children (either single or multifaceted) may be associated with some beneficial effect on asthma control, but no conclusive evidence exists regarding rhinitis or eczema. Conversely, there is little evidence to support the recommendation of allergen avoidance methods in adults with asthma and rhinitis. There is a need for an adequately designed trial assessing the effects of a multifaceted intervention in this age group.

Effectiveness of Indoor Allergen Reduction in Management of Asthma

Purpose of Review To evaluate the effectiveness of indoor allergen reduction interventions on asthma outcomes. Key Messages • Evidence for single interventions designed to reduce indoor allergen exposure on asthma outcomes is lacking. • Multicomponent interventions that bundle more than one strategy may improve some asthma outcomes, but it is unclear if specific combinations are more effective than others. • Multicomponent interventions that include high-efficiency particulate air-filtration (HEPA) vacuums or pest control reduce exacerbations and improve quality of life. • The evidence for both single and multicomponent interventions does not address many other important outcomes, including asthma-related health care utilization, pulmonary physiology, and asthma-related quality of life.