Late Breaking Abstract - Small airways dysfunction predicts asthma control and exacerbations: Longitudinal Data from ATLANTIS Study

Abstract

Rationale: While small airways dysfunction (SAD) is a feature of asthma, the association of SAD with relevant asthma outcomes is not entirely clear. The ATLANTIS study was designed to identify which physiologic and imaging variables best measures the presence and extent of SAD in asthma and its association with exacerbations, asthma control and quality of life.

Methods: 773 participants with mild, moderate and severe stable asthma were followed for one year with a six-month follow up. Physiologic tests included: spirometry, lung volumes, impulse oscillometry (IOS), multiple breath nitrogen washout (MBNW) and % fall in forced vital capacity during methacholine challenge. CT was performed to determine lung density ratio and lung volumes. We examined associations between these measurements and asthma control, exacerbations and quality of life using univariate and multivariate analyses.

Results: IOS, lung volumes, MBNW and FEF25-75 significantly correlated with exacerbations and asthma control by univariate analysis (Spearman correlations: 0.20-0.25, p < 0.00025; Bonferroni correction). A composite of IOS, the ordinal score, independently predicted asthma exacerbations and control in a multivariate analysis with known predictors of exacerbations (p < 0.05). Importantly, FEV1 was no longer a significant predictor of exacerbations when the ordinal score was included in the model. In contrast, CT parameters did not significantly correlate with exacerbations, asthma control, or quality of life.

Conclusion: SAD measured by IOS is associated longitudinally with important asthma outcomes such as asthma control and exacerbations.