THE RESPIRATORY EFFECTS OF REDUCTION OF MITE ALLERGEN IN THE BEDROOMSOF ASTHMATIC-CHILDREN - A DOUBLE-BLIND CONTROLLED TRIAL

Background Inhalation of house dust mite (HDM) allergen may provoke at tacks of asthma. Objective We investigated whether a double-blind plac ebo-controlled community-based study aimed at reducing the HDM allerge ns in the bedrooms of HDM sensitive asthmatic children using the best methods available would prove beneficial to the children's health. Met hods The children (mean age 9.9 years, 34 boys) were recruited by a qu estionnaire submitted to 7386 families in a geographically-defined are a of the UK. Subjects were chosen to take part in the double-blind pla cebo-controlled trial if they were asthmatic, skin sensitive to mites, and had mite allergen in their mattresses. Seventy children were rand omly allocated to groups. In the active group, the children's bedrooms were treated with an acaricide (Acarosan) and the mattresses, pillows and duvets were encased in exclusion covers. The control group receiv ed placebo treatments. Results Forty-nine complete data sets were obta ined. Applying bedding covers and Acarosan led to a median reduction o f 480 ng (100%) in mite allergen on the mattress vs 215 ng (53%) reduc tion in placebo-treated group by 6 weeks. No evidence was found that t he acaricide reduced mite allergen level. A change in bronchial reacti vity to histamine was observed in the children after 6 weeks. This was not associated with any change in thrice-daily records of peak expira tory flow rate. By 24 weeks, the actively-treated children had improve d forced expiratory volume in 1s (FEV(1)) and fewer required bronchodi lator therapy or reported asthmatic symptoms than did the controls. Co nclusions The results suggest that mite removal procedures may modestl y improve mite-sensitive asthmatics and could perhaps be of value in e xceptionally mite-sensitive and/or highly mite-exposed individuals who se response to the attempted removal should be measured.