Bronchial hyperreactivity in young children is an independent risk factor for later asthma

Background: Wheezing in preschool years is common but prediction of later asthma remains complex. We assessed whether an indirect airway challenge test evaluated by the forced oscillation technique (FOT) in young children may predict later asthma. Methods: In a prospective cohort of 78 preschool children (27 boys), with and without previous wheezing episodes, an adenosine-59-monophosphate (AMP) airway challenge protocol, skin prick testing (SPT), and a questionnaire were applied. Increase in respiratory resistance at 8 Hz of 2.0 hPa/s/L or 30% was considered as positive AMP test, i.e. bronchial hyperreactivity. A structured interview was applied at school age. Results: At baseline, mean age (range) was 4.7 (2.3-6.7) years, 45 (58%) had one or more wheezing episodes during the last 12 months. 38 (49%) had a positive AMP test. At follow-up (n = 62), age was 8.3 (6.0-10.9) years and 23 (43%) had asthma. A positive AMP test at preschool age was related to later asthma, odds ratio (95% CI) 8.4 (2.4 – 29.7). This association remained statistically significant in a multivariable regression model after adjusting for sex, age at baseline and at follow-up, positive SPT, and passive smoke exposure. A positive AMP test was not related to atopic symptoms other than asthma. Conclusion: In young children, bronchial hyperreactivity assessed by the AMP test may help to predict later asthma.