Purpose of review: Allergen avoidance is recommended as part of the treatment programme of many patients with allergic diseases in Europe and the USA. However, clinical trials of allergen avoidance tend to be small and the findings inconsistent. Several larger studies have recently been published, making a review of the new literature timely.
Recent findings: There have been two large double-blind, placebo-controlled studies on the use of encasings (mattress, pillow and duvet) as a single intervention in adults with asthma. In both studies, participants in the active and the control group showed an improvement in peak flow, but there was no difference between groups over a 12-month period. A further smaller study of encasings reported an improvement in peak flow from 1 week in the active group; this study, however, was only of 9 weeks’ duration. In children, the use of encasings was associated with a reduction in asthma medication usage, but not until 6 months into the study. A multifaceted intervention study, with the intervention tailored to the child's sensitization status and home environment (including environmental tobacco smoke), resulted in significant reductions in emergency room visits and symptoms in the active group.
Summary: The evidence suggests that interventions in children (either single or multifaceted) are associated with a meaningful and sustained improvement in asthma control. However, for adults, allergen proof encasings as a single intervention cannot be recommended. There is a need for a large-scale multifaceted intervention study in adults with asthma.