Title : Severe small airway dysfunction predicts loss of control in preschool-aged children with well-controlled asthma.
Abstract:
Background: Children whose asthma is considered clinically well controlled continue to experience loss of control and exacerbations. One explanation is failure to recognize the small airways as major sites of inflammation and obstruction. Oscillometry is an effort-independent technique that identifies small airway dysfunction (SAD) in young children.
Objectives: To determine the prevalence of SAD and severe SAD in well-controlled preschool children with asthma and their associations with subsequent loss of control and exacerbations.
Methods: In this prospective longitudinal study, 41 preschool-aged children with guideline-based well-controlled asthma underwent baseline oscillometry and were followed for up to 15 months. SAD was classified by Z score as non-severe (>1.645 to <3.0) or severe (>3.0). Logistic regression was used to evaluate associations of SAD severity with loss of control and exacerbations, adjusting for prior exacerbations.
Results: Non-severe SAD was present in 26.8% of children and severe SAD in 24.4%. Loss of control occurred in 80% of children with severe SAD, compared with 27.3% with non-severe SAD and 40% without SAD (p = .040). Severe SAD was independently associated with loss of control (adjusted odds ratio [aOR] 7.03; 95% CI, 1.03-48.03; p = .047). The association with exacerbations was in the same direction but did not reach statistical significance (aOR 3.49; 95% CI, 0.70-17.36; p = .127).
Conclusions: SAD was present in approximately half of this cohort and severe SAD in nearly one quarter. Severe SAD independently predicted loss of control. These preliminary findings suggest that SAD severity, rather than presence alone, identifies risk in children considered well controlled.
