Studies doubt value of mite-proof bed coverings

Studies doubt value of mite-proof bed coverings

Associated Press

Thursday, July 17, 2003

Boston — Two studies have found that mite-proof bed coverings, at least by themselves, fail to relieve asthma and allergies, a perplexing discovery that challenges the frequent advice of doctors.

Doctors and medical groups widely recommend mite-proof bed coverings to treat allergies and the asthma they can cause.

Up to 50 million Americans have allergies. Studies suggest that 40% to 60% of allergy sufferers in some areas are sensitive to dust mites, near-microscopic creatures that live in house dust and lay eggs in bedding. The tightly woven coverings — typically priced around $120 for a set — hold in their irritating allergens and keep new mites from bedding.

“My son had bad allergies, so we bought them — and I don’t think we would now,” said Jeffrey Drazen, a respiratory specialist who is editor-in-chief of the New England Journal of Medicine. “They deserve to work. It made sense.”

The findings of the two European studies, reported today in the journal, were so surprising that some doctors vowed to keep recommending bed coverings.

“For my patients, I wouldn’t dream of not doing it,” said Thomas Platts-Mills, a University of Virginia allergist who wrote an accompanying commentary on the studies. “It’s on the side of the angels: You’re not taking drugs.”

Although small previous studies reached mixed conclusions on the value of bed coverings, there is strong evidence that blocking allergens relieves symptoms. For example, asthmatics improve at clinics or hospitals with fewer mites.

Yet, in a seeming paradox, the yearlong European studies found no difference in symptoms between people with and without bed coverings. The English study was the largest of its kind, with 1,122 asthma patients. The Dutch study looked at 232 patients with hayfever-like allergies.

The researchers and specialists familiar with their findings said there might be so many dust mites around homes that they can largely eclipse the effects of mites in bedding.

Some research also suggests that asthma may perpetuate itself after prolonged exposure, even once the irritants are removed, said Adnan Custovic, supervisor of the English study and allergist at Wythenshawe Hospital, in Manchester, England.