Figure 1.

Schematic overview of the study design and FEV₁% predicted and FEV₁/FVC ratio among ever-smokers. (A) Flowchart of the recruitment, exclusions, dropouts, measurements, and results in evaluating the diagnostic accuracy of spirometry (FEV₁/FVC < 70%) in the detection of emphysema, as defined by CT quantification (Low Attenuation Area; LAA ≥ 7%) is shown. The number of participants recruited, excluded, and measured is shown within the respective boxes. ^# Four subjects were excluded (three for concomitant lung disease; one for α-1-antitrypsin deficiency). ^¶ Six total subjects did not have CT performed (two expired; three lost to follow-up; one withdrew consent). (B) FEV₁% predicted was plotted by age group among current (N = 133, solid circles) and former (N = 91, open circles) smokers. (C) FEV₁/FVC ratio was plotted by age group among current (N = 133, solid circles) and former (N = 91, closed circles) smokers. The group means are depicted by solid (current smokers) and dashed (former smokers) lines. * P < 0.05 current smokers versus former smokers.