Airway tone dysfunction among pre-schoolers with positive asthma predictive index: A case-control study.

OBJECTIVE: To measure lung function by impulse oscillometry (IOS) and spirometry in recurrent wheezer pre-schoolers according to their asthma predictive index (API) condition.

METHODS: We performed a case-control study enrolling all pre-schoolers with recurrent wheezing episodes (>3 episodes confirmed by physician) who presented at a paediatric pulmonology clinic. The population was divided according to stringent API criteria into positive or negative.

RESULTS: In the nine-month period, 109 pre-schoolers were enrolled. After excluding one patient (due to lung function technique problems) 108 pre-schoolers (56 males, age range from 24 to 72 months) completed the study; 50 belong to positive API and 58 to negative API group. There were no differences in demographics between groups. More use of ICS was found in those with positive API than with negative API (62% vs. 12%, respectively, p=0.001). No differences in basal lung function and post-bronchodilator response to salbutamol (by IOS or spirometry) were found between positive and negative API pre-schoolers. However, those positive API pre-schoolers with ICS had significantly higher central basal airway resistance (RA at 20Hz) and higher post-BD response (% change in FEF25-75 and in FEV0.5 ) than those positive API without ICS.

CONCLUSION: Recurrent wheezer pre-schoolers with positive API and ICS used may have airway dysfunction. More studies are needed to confirm this finding.