The effect of exacerbations on lung density in α-antitrypsin deficiency.

Background: Acute exacerbations of COPD (AECOPD) have unclear impacts on emphysema measurement using computed tomography (CT)-derived 15th percentile lung density (PD15). The aim of this study was to assess the influence of AECOPD on PD15 lung density in α-antitrypsin deficiency.

Methods: In a analysi of the RAPID (Randomised Trial of Augmentation Therapy in α-Proteinase Inhibitor Deficiency) trial, raw marginal residuals of PD15 (measured - predicted) were determined by fitting a regression line to individual patient CT data.