Abstract
Study Objective: To determine the frequency of relapse of asthma in young adults in remission at age 18, during a follow-up period of 8 years, and to identify possible prognostic markers for relapse. Design: Longitudinal study of birth cohort (n=1037) born in New Zealand in 1972/3. Setting: University Hospital research clinic.
Measurements: Participants were assessed at age 9, 11, 13, 15, 18, 21 and 26 using a respiratory questionnaire (all ages), spirometry (all ages), bronchodilator response (ages 18 and 26), methacholine challenge (ages 9, 11, 13, 15 and 21) and allergen skin prick testing (ages 13 and 21).
Results: Approximately one third (35%) of study members whose asthma was in remission at age 18 experienced relapse by age 21 or 26. Atopy and lower FEV1/VC ratio at age 18 were significant independent prognostic factors for relapse in multiple logistic regression analyses. Increased responsiveness to methacholine (PC20 less than 8mg/ml) or bronchodilator (improvement in FEV1 of 10% or greater) at age 21 were more common among those who relapsed, but the positive and negative predictive values for a previous positive methacholine challenge test at age 15 were low. Asthma after relapse was generally mild (mean FEV1 97.1% predicted). Totally new adult asthma developed by age 26 in 9% of study members who had no asthma or wheezing at any time up to age 18.
Conclusions: Subsequent relapse of previously diagnosed asthma which is in remission at age 18 occurs in one in three young adults. Such relapse is not easily predicted, especially by measurements of airway responsiveness. A history of asthma currently in remission should not be used to prejudice employment opportunities for young adults.