One third of children with asthma who go into remission by the age of 18 will relapse and redevelop asthma by the time they are 26, says a new study published in the March issue of CHEST, the peer-reviewed journal of the American College of Chest Physicians.
The findings also suggest that children with certain common allergies, such as house dust mite sensitivity, and/or poor lung function are more likely to redevelop asthma following remission.
"While we cannot definitively explain why some individuals experience asthma relapse and others do not, we found that persistence of asthma and asthma relapse are significantly increased in children with house dust mite sensitivity," said study author, Malcolm R. Sears, MB, ChB, FRCPC, McMaster University, Hamilton, Ontario, Canada. "This is likely due to persistent inflammation and genetic factors."
In a longitudinal, population-based, cohort study of 1,037 children born in New Zealand between 1972 and 1973, researchers from Dunedin, New Zealand, and Hamilton, ON, Canada, looked at factors that influenced the reoccurrence of asthma by early adulthood. Study participants were given respiratory questionnaires and spirometry testing at ages 9, 11, 13, 15, 18, 21, and 26, as well as additional lung function and allergen skin-prick testing at select ages. Of 868 patients evaluated at age 18, 176 (20.3 percent) had physician-diagnosed asthma during childhood, and, of those, 68 (38.6 percent) no longer experienced any asthma symptoms (measured by self-reported wheezing). During an eight-year follow-up period, researchers found that 24 of the 68 study participants (35 percent) who had previously gone into remission, relapsed by age 26. Although not statistically significant, the patients who relapsed more often had allergies to house dust mites, grass, cats, dogs, and mold; poorer lung function (measured by FEV1/FVC ratios at age 18); and increased frequency of responsiveness to methacholine or bronchodilator at age 21.