Table 4.

Estimated effects of the smoking status at baseline and over time on the hazard of subsequent lung function deterioration*

Smoking status	HR (95 % CI) Unadjusted	P value	HR (95 % CI)	P value Adjusted†
Baseline non-smoking	0.25 (0.07-0.85)	0.027	0.30 (0.09-1.00)	0.05
Time-dependent non-smoking	0.25 (0.08-0.97)	0.04	0.34 (0.10-1.14)	0.08
No smoking during the past six months	0.25 (0.07-0.84)	0.025	0.29 (0.08-0.97)	0.044
No smoking during the past 12 months	0.23 (0.07-0.79)	0.020	0.28 (0.08-0.97)	0.045
No smoking during the study period	0.22 (0.06-0.73)	0.014	0.28 (0.08-0.94)	0.040

Definition of abbreviations: FEV ₁ forced expiratory volume in 1 second, FVC forced vital capacity, DL _CO diffusion capacity for carbon monoxide, HR hazard ratio, CI confidence interval.

*Lung function deterioration was defined as a decrease of at least 15% in FEV₁, FVC and/or DL_CO compared with the baseline values.

†The adjustment predictive factor at inclusion was baseline PaO₂, as selected by the multivariable prognostic model.