Longitudinal changes in airway remodeling and air trapping in severe asthma

Abstract

Rationale and Objectives: Previous cross-sectional studies have demonstrated that airway wall thickness and air trapping are greater in subjects with severe asthma than in those with mild-to-moderate asthma. However, a better understanding of how airway remodeling and lung density change over time is needed. This study aimed to evaluate predictors of airway wall remodeling and change in lung function and lung density over time in severe asthma. Materials and methods: Phenotypic characterization and quantitative multidetector-row computed tomography (MDCT) of the chest were performed at baseline and ~2.6years later in 38 participants with asthma (severe n=24 and mild-to-moderate n=14) and nine normal controls from the Severe Asthma Research Program. Results: Subjects with severe asthma had a significant decline in postbronchodilator forced expiratory volume in 1 second percent (FEV1%) predicted over time (P < .001). Airway wall thickness measured by MDCT was increased at multiple airway generations in severe asthma compared to mild-to-moderate asthma (wall area percent [WA%]: < .05). In a multivariable regression model, baseline WA%, race, and health care utilization were predictors of subsequent airway remodeling. Conclusions: Severe asthma subjects have a greater decline in lung function over time than normal subjects or those with mild-to-moderate asthma. MDCT provides a noninvasive measure of airway wall thickness that may predict subsequent airway remodeling. © 2014 AUR.