Table 4

Results of regression analyses for annual rates of change (time slopes) for FVC, FEV₁, and FEV₁/FVC for subjects in the coke oven lung function surveillance system after the exclusion of 111 subjects without detailed work histories

	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	33.9	4.19 to 63.6	0.0254	49.8	24.2 to 75.3	0.0001	3.3	2.61 to 4.00	0.0001	100	27.8 to 173	0.0068
% of predicted value at first test time	−0.386	−0.698 to −0.072	0.0159	−0.531	−0.792 to −0.270	0.0001	−0.0323	−0.038 to −0.025	0.0001	−0.674	−1.31 to −0.035	0.0388
Duration of smoking for ex-smokers (y)	−0.373	−0.771 to 0.024	0.0657	−0.596	−0.986 to −0.206	0.0028	−0.0130	−0.019 to −0.006	0.0001	−0.997	−2.82 to 0.824	0.283
Pack-years for current smokers	−0.477	−0.784 to −0.170	0.0024	−0.661	−0.962 to −0.360	0.0001	−0.0107	−0.015 to −0.005	0.0001	−1.29	−2.64 to 0.0670	0.0624
Work duration in “operation” (y)	−1.03	−1.72 to −0.334	0.0038	−0.762	−1.44 to −0.080	0.0284	−0.00110	−0.012 to 0.010	0.852	−0.666	−3.82 to 2.48	0.678
Work duration other than in “operation” (y)	−0.661	−1.24 to −0.075	0.0270	−0.472	−1.04 to 0.101	0.106	0.00225	−0.007 to 0.012	0.651	0.0277	−2.64 to 2.69	0.984
R²	0.0559			0.0834			0.185			0.0193
Number of observations	469			469			469			355