Can Bronchial Provocation Test at Preschool Asthma Predict Asthma at School Age?

Background: While bronchial challenge test (BCT) measures current airways-hyperreactivity, the predictive role of BCT, in pre-school children (<6yo) for the diagnosis of asthma at school-age is still under debate. We aimed to find whether preschool children with a positive BCT are more prone to asthma at school-age.

Methods: We included children aged 6-13 years with respiratory symptoms that were previously referred to our PFT laboratory for BCT (methacholine or adenosine) at age 10 months to 6 years (baseline). BCT was considered positive based on spirometry results or wheezing, desaturation and tachypnea reactions. The primary outcome measure was asthma diagnosis at school-age using the well-validated International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. We used logistic regression analysis to explore whether positive BCT could predict school-age asthma while including age and collected modified asthma predictive index (mAPI) in the model.

Results: 151/189 children (53% males), completed the ISAAC (response rate=79.9%). Mean age at BCT and at follow-up were 3.9±1.28 and 9.4±1.85 years, respectively. At baseline, 73/84 had positive methacholine BCT and 40/67 had positive adenosine test. Thirty-nine children were diagnosed with asthma according to ISAAC at school-age. Logistic regression analysis showed that a positive adenosine test at pre-school age was the best predictor, significantly increasing the odds of asthma at school-age by 6.34 (95%CI=1.23-32.81, p=0.028), while methacholine did not show significance (p=0.69).

Conclusion: In our population, positive adenosine test, mAPI, but not methacholine, at pre-school age, can predict asthma at school-age.