Table 5– Univariate prognostic analyses of the factors measured at diagnosis that were candidates for predicting the incidence of airway obstruction^#

Characteristic	HR (95% CI)	p-value
Age per 10 yrs	0.93 (0.52–1.67)	0.81
Smoking per 10 pack-yrs	1.06 (0.87–1.28)	0.56
Dyspnoea	1.01 (0.42–2.39)	0.99
TLC % pred^¶	1.17 (0.91–1.50)	0.22
FVC % pred^¶	0.75 (0.57–0.99)	0.04
FEV₁% pred^¶	0.59 (0.45–0.77)	0.0001
FEV₁/FVC %^¶	0.54 (0.42–0.69)	0.0001
RV % pred^¶	1.16 (1.08–1.26)	0.0002
RV/TLC % pred^¶	1.24 (1.11–1.39)	0.0002
D_L,CO% pred^¶	0.04 (0.03–0.47)	0.01
HRCT nodular score	0.91 (0.80–1.03)	0.13
HRCT cystic score	1.13 (1.05–1.21)	0.0009

HR: hazard ratio; TLC: total lung capacity; % pred: % predicted; FVC: forced vital capacity; FEV₁: forced expiratory volume in 1 s; RV: residual volume; D_L,CO: diffusing capacity of the lung for carbon monoxide; HRCT: high-resolution computed tomography. ^#: A total of 21 (43%) out of 49 patients had an obstructive pattern (FEV₁/FVC <70%) at any time during the study; ^¶: the HR is calculated for 10% variations in the predicted values.