Figure 1.
Upper panel: Ratio of volume to surface area (V:SA) as a measure of total wall thickness related to FEV1 in 159 patients with chronic obstructive pulmonary disease (COPD) at different Global Initiative on Obstructive Lung Disease (GOLD) stages. Lower panel: Thickness of epithelium, lamina propria, smooth muscle, and adventitial tissue expressed as total wall thickness (V:SA), and the percentage of airways containing lymphoid follicles in various GOLD stages. *p < 0.001 compared with GOLD stage 0; †p < 0.001 compared with GOLD stage 1; ‡p < 0.001 compared with GOLD stage 2. Reprinted by permission from Reference 3.