Encasement of Bedding Does Not Improve Asthma in Atopic Adult Asthmatics

Abstract

Aim: We evaluated the impact of impermeable bed covers on asthma in asthmatics with clinically relevant house dust mite (HDM) sensitization. Methods: The study included 32 HDM-sensitized asthmatics in whom HDM allergy was considered as a significant factor in their asthma. They were randomized into either an intervention group whose bedding was encased with impermeable covers, or a control group who received cotton covers. Before and 3 and 6 months after encasement, dust samples were collected from the bedding and assayed for Der p 1. Clinical outcomes included quality of life, lung function, bronchial reactivity to methacholine, symptoms, medications and peak flow rates. Results: Baseline Der p 1 levels in both the active and the placebo groups were comparable and high (19.2 vs 18.9 µg/g of dust). There was a significant reduction in Der p 1 levels in the active group after 6 months, but not in the placebo group (7.3 vs 21.9 µg/g of dust). Quality of life improved significantly in both the intervention and control groups, but there was no significant difference in the improvements between the groups. There was no significant change in lung function, symptoms, and requirements for medications. Conclusions: Encasement of bedding significantly reduced the Der p 1 levels. However, this was not sufficient to produce worthwhile clinical improvement in those in whom dust mite avoidance might well have been recommended as part of their clinical management.

Nonpharmacological and pharmacological interventions to prevent or reduce airway remodelling

“…This is highlighted by the findings of WOODCOCK et al [80], which showed that allergen-impermeable covers as a single intervention in the avoidance of exposure to HDM allergen were clinically ineffective in adult asthmatics. The current authors have found similar negative findings in a HDM avoidance study directed specifically at patients in whom HDM was clinically relevant [81].…”

Mite penetration of different types of material claimed as mite proof by the Siriraj chamber method

“…It was evident from this study that the nonwoven fabrics will allow surface penetration, and in some cases they appeared to allow colonization. Additionally, it was observed that normal use of fabrics made this more likely, as shown in Fig 2. Although clinical recommendations for use of encasings remains controversial, [15][16][17] at least in terms of primary prevention of allergies, it is clear that the materials used to construct covers have not been adequately considered, and the design in some cases remains suboptimal. Ideally, such covers should both provide comfort by allowing transfer of air and moisture, as well as preventing the passage of allergens and the colonization by mites.…”

Anti-mite Covers: Potential Criteria for Materials Used Against Dust Mites

“…To our knowledge, no experimental, non-clinical study has evaluated the structural integrity of tightly woven covers for withstanding mite and allergen penetration after repeated washings and use over a long period of time. However, a number of studies have recorded allergen decrements as a result of impermeable encasements alone after nine weeks [5], six months [27,28], and one year [22,23], which suggests that the structural integrity of these encasements was not compromised.…”