Woodcock A, Forster L, Matthews E. N Engl J Med. 2003;349:225–236
Purpose of the Study.
To determine whether decreased exposure to house dust mites improves control of asthma among adults.
A total of 1222 adults with asthma who were being treated with inhaled corticosteroids and required short-acting β-receptor agonist treatment more than once per day were studied.
This was a double-blind, randomized, placebo-controlled study of the use of impermeable mattress covers among adults with symptomatic asthma. House dust mite antigen levels were measured in mattress dust at baseline, 6 months, and 12 months.
The prevalence of sensitivity to house dust mite allergen was ∼65% in both the active intervention group (allergen-impermeable bed covers) and the control group (permeable bed covers). The concentration of house dust mite antigen for the treated group was 33% of that for the control group at 6 months, but levels were not different at 12 months. The mean morning peak expiratory flow improved significantly in both groups. There was no significant difference in inhaled corticosteroid doses.
Use of impermeable mattress covers brought no significant change in symptom control, pulmonary function, or inhaled corticosteroid doses among adults with asthma.
Another study in the same issue showed no difference in allergic rhinitis symptom control among patients randomized to receive allergen-impermeable bed covers, as opposed to sham covers. It may be postulated that there is no single intervention strategy that, by itself, significantly affects immunoglobulin E-mediated upper and lower airway involvement. This does not exclude the possibility that control of house dust mite exposure, in addition to other active treatments and more comprehensive environmental control measures, may have beneficial effects for selected patients.