Table 3

Results for regression analyses for annual rates of change (time slopes) for FVC, FEV₁, FEV₁/FVC, and FEF_25–75% for all subjects in the coke oven lung function surveillance system

	FVC (ml/year)			FEV₁ (ml/year)			FEV₁/FVC (%/year)			FEF_25–75% (ml/s⋅year)
	Coefficient	95% CI	p value	Coefficient	95% CI	p value	Coefficient	95% CI	p value	Coefficient	95% CI	p value
FEF_25–75% was measured after January 1983, so the observation number is smaller than that for FVC, FEV₁, and FEV₁/FVC.
Intercept	29.7	4.26 to 55.2	0.0222	43.0	21.3 to 64.8	0.0001	3.10	2.47 to 3.73	0.0001	82.0	18.7 to 145	0.0112
% of predicted value at first test time	−0.383	−0.655 to −0.110	0.0061	−0.496	−0.722 to −0.270	0.0001	−0.0306	−0.36 to −0.24	0.0001	−0.610	−1.18 to −0.046	0.0342
Duration of smoking for ex-smokers (y)	−0.317	−0.676 to 0.042	0.0841	−0.528	−0.878 to −0.178	0.0032	−0.0111	−0.017 to −0.005	0.0004	−0.597	−2.25 to 1.06	0.478
Pack-years for current smokers	−0.496	−0.778 to −0.214	0.0006	−0.608	−0.884 to −0.333	0.0001	−0.00897	−0.013 to −0.004	0.0003	−1.10	−2.36 to 0.159	0.0865
Work duration in “operation” (y)	−0.682	−1.25 to −0.110	0.0195	−0.484	−1.04 to 0.072	0.0882	0.0002	−0.009 to 0.009	0.968	−0.0106	−2.71 to 2.50	0.936
Work duration other than in “operation” (y)	−0.591	−1.12 to −0.064	0.0278	−0.428	−0.940 to 0.082	0.100	0.0025	−0.006 to 0.011	0.582	0.0176	−2.37 to 2.41	0.989
R²	0.0506			0.0732			0.159			0.0147
Number of observations	580			580			580			419