House dust mite barrier bedding for childhood asthma: randomised placebo controlled trial in primary care [ISRCTN63308372]

Pragmatic, randomised, double-blind, placebo controlled trial conducted in eight family practices in England. Forty-seven children aged 5 to 14 years with confirmed house dust mite sensitive asthma were randomised to receive six months treatment with either house dust mite barrier or placebo bedding. Peak expiratory flow was the main outcome measure of interest; secondary outcome measures included asthma symptom scores and asthma medication usage.No difference was noted in mean monthly peak expiratory flow, asthma symptom score, medication usage or asthma consultations, between children who received active bedding and those who received placebo bedding.Treating house dust mite sensitive asthmatic children in primary care with house dust mite barrier bedding for six months failed to improve peak expiratory flow. Results strongly suggest that the intervention made no impact upon other clinical features of asthma.Asthma is now the commonest chronic disease of childhood in the UK and evidence strongly suggests recent increases in prevalence and severity of the condition. [1-3] Aetiologically, changes to the indoor environment have been implicated in both these increases; proliferation in British homes of soft furnishings, wall-to-wall carpets, central heating, and double glazing, together with the tendency for children to spend more time indoors, have all combined to increase exposure to airborne indoor allergens.[4] This pathophysiological element in the aetiology of asthma is reflected in the current British Thoracic Society Guidelines on Asthma Management which advise allergen avoidance should be considered in the treatment of all patients with asthma.[5]The allergen most commonly implicated in the UK is house dust mite, mattresses, bedding, and carpets forming its most important domestic reservoirs. A number of approaches to decreasing house dust mite exposure have been tried, of which house dust mite impermeable bedding is the most promising.[6] New semi-permeable