How much do GOLD stages reflect CT abnormalities in COPD patients?

Abstract

Severity of chronic obstructive pulmonary disease (COPD) can be graded using the classification released in the Global Initiative for Chronic Obstructive Lung Disease (GOLD) report. Such classification is essentially based on spirometry and does not recognise the role of other measures. The aim of this study was to assess whether the GOLD stages correlate with the extent of pulmonary emphysema and other ancillary computed tomography CT features in a population of smokers with stable COPD. Based on clinical assessment and lung-function testing, patients were classified according to the GOLD criteria. CT scans were visually evaluated for extent of emphysema and airway abnormalities. A total of 43 patients were enrolled. The amount of emphysema was described as minimal in six patients with stage 0, and as moderate in seven patients with stage 0. In stages I and II, the extent of emphysema ranged from minimal to severe, whereas we observed the presence of severe emphysema in most patients in stages III and IV. According to the regression model, only CT emphysema extent independently predicted the GOLD stage (r2 = 0.58; p < 0.001). The cutoff value of emphysema extent of 31.5% allowed us to distinguish patients with a GOLD stage > or = III. Although we found a significant correlation between CT emphysema extent and GOLD stages, different percentage of emphysema extent can be observed among each GOLD stage. The upper limit of 31.5% of emphysema extent may indicate a boundary for a clinically worsening status.