Table 3.

Partial correlations between lung air-trapping on CT with arterial stiffness in COPD patients and controls

	Carotid β-Stiffness Index	Carotid-Femoral PWV	Carotid IMT
COPD and Controls
Air-trapping (Exp/Insp mean attenuation ratio) adjusting for age, MAP, pack-years and FEV1	0.64*	0.12	−0.12
Air-trapping (% of lung voxels <−865 HU at RV) adjusting for age, MAP, pack-years, and FEV1	0.71**	−0.10	−0.39
COPD only
Air-trapping (Exp/Insp Mean attenuation ratio) adjusting for age, MAP, pack-years, and FEV1	0.82*	0.12	0.05
Air-trapping (% of lung voxels <−865 HU at RV) adjusting for age, MAP, pack-years, and FEV1	0.91*	−0.16	−0.22

Data are partial correlation coefficients for β-stiffness and pulse wave velocity (PWV). Carotid β-stiffness was not adjusted for mean arterial pressure (MAP) because it is pressure independent. COPD, chronic obstructive pulmonary disease; CT, computed tomography; Exp, expiratory; FEV₁, forced expiratory volume; HU, Hounsfield units; IMT, intima-media thickness; Insp, inspiratory; RV, residual volume.

^*P < 0.05,

^**P < 0.01.