Bedcovers which form a barrier to house dust mites appear to reduce asthma flare ups in children, according to new research conducted by the University of Manchester (University of Manchester, 2017).

Mite allergy is one of the most common asthma triggers, and in partnership with viral infection can greatly increase hospital admission risk. In the study, led by Dr Clare Murray, clinical senior lecturer at The University of Manchester and consultant respiratory paediatrician at the Royal Manchester Children’s Hospital, children aged between three and seventeen were enrolled who had tested positive for mite allergy, and suffered an asthma flare up or exacerbation that required being treated in accident and emergency or as a hospital inpatient.

After encasing their mattresses, duvets and pillows with mite-proof covers or placebo covers, the children were followed for a year. The findings have been published online ahead of print in the American Thoracic Society’s American Journal of Respiratory and Critical Care Medicine. Results show the children sleeping with the mite-proof covers were 41.5% less likely to have a severe asthma exacerbation that resulted in an accident and emergency visit or hospital admission. They were 45% less likely of having an asthma exacerbation that resulted in an A&E visit or hospitalisation and the requirement for systemic corticosteroids. They also went a significantly longer time to their first exacerbation that resulted in an A&E visit or hospitalisation and the requirement for systemic corticosteroids.

Patients were recruited from fourteen hospitals with acute paediatric secondary care services in the North West of England. The study was funded by The JP Moulton Charitable Foundation, and infrastructure support was provided by the North West Lung Centre Charity, situated at University Hospital of South Manchester, where Clare Murray’s research team is based.

Clare Murray said “Asthma exacerbations are among the most common reasons for hospitalizing children living in the developed world. It’s a frightening experience for children and their parents, and a single exacerbation can increase the annual cost of treating asthma by three-fold.”

Clare Murray said viral infections, especially those causing the common cold, are a major risk factor for asthma exacerbations in children sensitised and exposed to allergens. She said “Other studies have shown that these two risk factors act synergistically to increase the likelihood of hospital admission by nearly 20-fold. We have no means of protecting people from cold viruses, but our study indicates that allergen avoidance may be a cost-effective intervention.”

The authors estimated the cost of the bedcovers would be about £130 for a single bed. Clare Murray said “This simple measure may reduce asthmatic exacerbations that lead to accident and emergency visits or hospitalisation, particularly in younger children who are allergic only to dust mites.”

The mite-proof covers did not significantly reduce the number of children whose exacerbation was treated outside the hospital with only an oral corticosteroid. The authors said it was not clear why this was the case. Clare Murray said “It may be that the bedcovers did not prevent the exacerbation, but did reduce its severity.”

Limitations of the study, which is believed to be the first to study the effect of mite-proof bedcovers and asthma exacerbations, include the fact that the exacerbations and oral corticosteroid use were reported by parents or guardians, not physicians, and the researchers had no information about viruses or other exacerbation triggers.

Although the study was not large enough to conclusively define the subgroups that benefitted the most from the intervention, the authors wrote that their results suggested that younger children testing positive for only house dust mite allergy and living in non-smoking households were more likely to benefit from the mite impermeable bed covers.