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)FEF25–75% (ml/s⋅year)
Coefficient95% CIp valueCoefficient95% CIp valueCoefficient95% CIp valueCoefficient95% CIp value
FEF25–75% was measured after January 1983, so the observation number is smaller than that for FVC, FEV1, and FEV1/FVC.
Intercept33.94.19 to 63.60.025449.824.2 to 75.30.00013.32.61 to 4.000.000110027.8 to 1730.0068
% of predicted value at first test time−0.386−0.698 to −0.0720.0159−0.531−0.792 to −0.2700.0001−0.0323−0.038 to −0.0250.0001−0.674−1.31 to −0.0350.0388
Duration of smoking for ex-smokers (y)−0.373−0.771 to 0.0240.0657−0.596−0.986 to −0.2060.0028−0.0130−0.019 to −0.0060.0001−0.997−2.82 to 0.8240.283
Pack-years for current smokers−0.477−0.784 to −0.1700.0024−0.661−0.962 to −0.3600.0001−0.0107−0.015 to −0.0050.0001−1.29−2.64 to 0.06700.0624
Work duration in “operation” (y)−1.03−1.72 to −0.3340.0038−0.762−1.44 to −0.0800.0284−0.00110−0.012 to 0.0100.852−0.666−3.82 to 2.480.678
Work duration other than in “operation” (y)−0.661−1.24 to −0.0750.0270−0.472−1.04 to 0.1010.1060.00225−0.007 to 0.0120.6510.0277−2.64 to 2.690.984
Number of observations469469469355