Table 3.

Association of Postbronchodilator FEV₁ to SVC Ratio of < 0.7 With Chest CT Scan Features in Smokers With Normal Spirometry Results^a (n = 854)

Variable	β (95% CI)	P Value
% Emphysema	0.45 (0.09-0.82)	.014
% Gas trapping	2.52 (0.59-4.44)	.010
% PRMfSAD	2.78 (0.72-4.83)	.0081

Each row represents a model. All models included the following covariates: age, sex, race, smoking status, and smoking pack-years at the enrollment. Data regarding % emphysema, % gas trapping, % PRM^fSAD, and current smoking were missing in 7, 4, 96, and 9 participants, respectively. PRM^fSAD = parametric response mapping functional small airways disease; SVC = slow vital capacity.

^aNormal spirometry results defined as postbronchodilator FEV₁ ≥ 80% and postbronchodilator FEV₁/FVC ≥ 0.7.