Clinical effectiveness of a mite allergen-impermeable bed-covering system in asthmatic mite-sensitive patients.
BACKGROUND
Exposure to allergens plays a role in the development of bronchial hyperresponsiveness and in the chronic inflammatory response seen in asthmatic patients. House dust mites (HDMs) are an important source of allergen. Reduction of these allergens might lead to better lung function and reduction of asthma symptoms.


OBJECTIVE
The effect of HDM-impermeable covers on HDM allergen levels, peak flow values, and asthma symptoms were measured. Therefore a randomized clinical trial was carried out.


METHODS
Fifty-two allergic asthmatic patients were randomly allocated to use the HDM-impermeable or placebo covers. During the study period, daily peak flow and asthma symptom scores were recorded. Dust samples were taken from the mattresses.


RESULTS
We observed a significant reduction in HDM allergen levels on the mattresses after encasing them with HDM-impermeable covers (reduction of 87% of Der p 1 in micrograms per gram of dust; P <.001). Baseline symptoms were so low that no improvement could be established. Morning peak expiratory flow is significantly higher in the intervention group compared with that seen in the placebo group during the study period (beta=20.2; P <.01).


CONCLUSIONS
HDM-impermeable covers significantly decreased the level of HDM allergens. Furthermore, morning peak flow was significantly increased during the intervention period. This study indicates that HDM allergen-avoidance measures might have beneficial effects on allergen reduction and asthma outcome.
van den Bemt
Lisette
L
Department of General Practice, Research Institute Caphri, Maastricht University, The Netherlands. L.vandenbemt@hag.umcn.nl
van Knapen
Lieke
L
de Vries
Marjolein P
MP
Jansen
Margreet
M
Cloosterman
Sonja
S
van Schayck
Constant P
CP
D000328:Adult; D039741:Antigens, Dermatophagoides / Q000009:adverse effects* / Q000276:immunology; D060829:Arthropod Proteins; D001249:Asthma / Q000276:immunology*; D001512:Bedding and Linens; D016535:Bronchial Hyperreactivity / Q000276:immunology; D003546:Cysteine Endopeptidases; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D010366:Peak Expiratory Flow Rate; D011446:Prospective Studies; D016896:Treatment Outcome
D039741:Antigens, Dermatophagoides; D060829:Arthropod Proteins; D003546:Cysteine Endopeptidases; C451162:Dermatophagoides pteronyssinus antigen p 1