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House dust mite exposure as a risk factor for asthma: benefits of avoidance
1Institute of Respiratory Medicine, University of Sydney, Australia. g.marks@unsw.edu.au
Abstract:
There is a dose-response relation between the level of exposure to house dust mite allergen and the risk of acquiring sensitization to this allergen as well as the risk of developing asthma. This relation is apparent at levels of exposure below 10 microg/g. In communities where nearly all houses have house dust mite allergen levels above this threshold, all susceptible individuals will be affected, and the relation to house dust mite exposure will not be apparent. Although these observational data would suggest that reducing exposure to house dust mite allergen should lessen the risk of developing sensitization and asthma, definitive evidence from randomized controlled trials is not yet available. Of the many clinical trials of house dust mite avoidance as therapy for asthma, only a few have produced sustained, substantial reductions in allergen levels in the bed. These effective interventions all included allergen-impermeable encasement of mattresses along with other strategies. In most trials where allergens levels were successfully reduced, there were clinical benefits for patients with asthma.
Insights
Reducing exposure to house dust mite allergen can lower the risk of sensitization and asthma. Effective avoidance strategies, like mattress encasement, show clinical benefits for asthma patients.
Area of Science:
- Allergy and Immunology
- Environmental Health
- Respiratory Medicine
Background:
- A dose-response relationship exists between house dust mite (HDM) allergen exposure and the risk of sensitization and asthma development.
- This relationship is observable at exposure levels below 10 microg/g.
- In highly exposed communities, the link may be obscured as susceptible individuals are universally affected.
Purpose of the Study:
- To examine the association between house dust mite allergen exposure and the risk of sensitization and asthma.
- To evaluate the effectiveness of house dust mite avoidance strategies in clinical trials for asthma therapy.
Main Methods:
- Observational data analysis to establish dose-response relationships.
- Review of clinical trials investigating house dust mite avoidance interventions for asthma.
- Assessment of methods for achieving sustained, substantial reductions in indoor allergen levels.
Main Results:
- A clear dose-response effect was noted, particularly below 10 microg/g of HDM allergen.
- Few clinical trials achieved significant and lasting reductions in HDM allergen levels, primarily through mattress encasement.
- Successful allergen reduction in trials often correlated with clinical benefits for asthma patients.
Conclusions:
- Reducing exposure to house dust mite allergen is likely to decrease the risk of sensitization and asthma.
- Allergen-impermeable encasement of mattresses, combined with other measures, is an effective strategy for reducing HDM exposure.
- Further randomized controlled trials are needed to definitively confirm the benefits of HDM avoidance in asthma prevention and management.