Asthma relapse linked to allergies

Researchers have found that some children who supposedly outgrew their asthma saw it re-appear by the time they reached their mid-20s.

Common allergies, such as a sensitivity to house dust mites, and those with poor lung function, seem likely to be the culprits.

It is not known why some individuals experience asthma relapse and others do not, but the persistence of asthma and asthma relapse are significantly increased in children with house dust mite sensitivity said Malcolm Sears of McMaster University in Canada; persistent inflammation and genetic factors could also be contributing factors.

Mr Sears and colleagues studied more than 1,000 children born in New Zealand between 1972 and 1973, testing them at ages nine, 11, 13, 15, 18, 21 and 26. Twenty per cent of them had asthma diagnosed by a doctor at some point in childhood. Thirty eight per cent were free of symptoms by the age of 18. By the age of 26, thirty five per cent said their symptoms came back. The patients who relapsed often had allergies to house dust mites, grass, cats, dogs, and mould.

"By not smoking and avoiding occupations that increase the likelihood of developing asthma, patients can help protect themselves from asthma relapse," Mr Sears said.

The study demonstrates the role that specific risk factors have on asthma remission, said Dr Paul Kvale, president of the American College of Chest Physicians.