Visual Emphysema at Chest CT in GOLD Stage 0 Cigarette Smokers Predicts Disease Progression: Results from the COPDGene Study

Background: The clinical significance of visually evident emphysema on CT images in individuals without spirometric evidence of chronic obstructive pulmonary disease (COPD) by current diagnostic criteria is, to the knowledge of the authors, unknown. Purpose: To evaluate whether participants with visually evident emphysema at CT were more likely to have progressive disease and increased mortality at 5 years compared with those without visual emphysema. Materials and Methods: This secondary analysis of the prospective Genetic Epidemiology of COPD study evaluated current or former smokers enrolled between 2008 and 2011 who did not meet current criteria for COPD (defined as Global Initiative for Obstructive Lung Disease stage 0). Statistical analysis was performed by using linear mixed models to estimate mean physiologic, imaging, and clinical outcomes for those with and without visual emphysema. Hazard ratios for mortality were calculated by using Cox regression models with emphysema as the main predictor. Results: Of the 4095 participants, 48.3% (1979 participants; 1096 men and 883 women; mean age, 57 years +/- 8 [standard deviation]) had trace or greater visual emphysema at CT and 51.7% (2116 participants; 1068 men and 1048 women; mean age, 56 years +/- 8) had no emphysema at CT. At 5 years, participants with visual emphysema at CT demonstrated progressive airflow obstruction with lower values of ratio of forced expiratory volume in 1 second (FEV1-to-functional vital capacity (FVC) ratio (-1.7 vs -0.7) and greater progression in quantitative emphysema measured by 15th percentile lung density (-3.3 vs -0.3 HU), adjusted lung density (-3.1 vs -0.2 g/L), and percentage of lung voxels with CT attenuation less than -950 HU (0.17 vs -0.20) than participants without emphysema (P<.001 for each). The rate of quantitative emphysema progression increased with greater grades of emphysema severity within the emphysema group. Conclusion: The presence of visual emphysema at CT in current and former Global Initiative for Obstructive Lung Disease stage 0 smokers predicted structural and physiologic disease progression. (C) RSNA, 2020