Table 3B: GEE model (approach 2): Effect estimates for longitudinal change of lung function parameters in relationship with concentration (in mg/m3) and duration (in dust-years) of coal mine dust exposure and covariables. No. of subjects = 1343.
VCmax (liters) | FEV1 (liters) | FEV1/VCmax (%) | |||||||
Covariable | Estimate | Std.Err | P > |z| | Estimate | Std.Err | P > |z| | Estimate | Std.Err | P > |z| |
Approach 2 | |||||||||
Coal mine dust concentration* | 0.012 | 0.013 | 0.370 | 0.014 | 0.014 | 0.329 | 0.108 | 0.186 | 0.563 |
Duration of exposure ** | 0.007 | 0.003 | 0.021 | 0.007 | 0.003 | 0.021 | 0.019 | 0.040 | 0.629 |
Height (in cm) | 0.063 | 0.002 | < 0.001 | 0.049 | 0.002 | < 0.001 | -0.057 | 0.025 | 0.023 |
Weight (in kg) | -0.005 | 0.001 | < 0.001 | -0.004 | 0.001 | < 0.001 | -0.006 | 0.010 | 0.532 |
Age ≤ 25 | -0.037 | 0.004 | < 0.001 | -0.035 | 0.003 | < 0.001 | -0.126 | 0.039 | 0.001 |
Age > 25 | -0.031 | 0.004 | < 0.001 | -0.034 | 0.003 | < 0.001 | -0.193 | 0.037 | < 0.001 |
Non-German nationality*** | -0.176 | 0.045 | < 0.001 | -0.195 | 0.042 | < 0.001 | -1.268 | 0.490 | 0.010 |
Active smoker*** | -0.148 | 0.022 | < 0.001 | -0.092 | 0.021 | < 0.001 | 0.202 | 0.252 | 0.424 |
Former smoker*** | -0.109 | 0.030 | < 0.001 | -0.020 | 0.028 | 0.458 | 0.918 | 0.345 | 0.008 |
Cumulative packyears | -0.004 | 0.001 | 0.008 | -0.007 | 0.001 | < 0.001 | -0.097 | 0.016 | < 0.001 |
Coking coal*** | 0.247 | 0.031 | < 0.001 | 0.069 | 0.030 | 0.021 | -2.457 | 0.361 | < 0.001 |
Custovit*** | 0.118 | 0.012 | < 0.001 | -0.032 | 0.011 | 0.004 | -2.467 | 0.169 | < 0.001 |
Vitalograph*** | 0.350 | 0.022 | < 0.001 | 0.385 | 0.022 | < 0.001 | 1.179 | 0.311 | < 0.001 |
Year of measurements | 0.008 | 0.004 | 0.047 | 0.019 | 0.004 | < 0.001 | 0.236 | 0.044 | < 0.001 |
Statistics: Hazard ratio with standard error, Wald test: z-value, two-sided p-value. *unit: In mg/m3; ** unit: dust-years; ***Reference: German nationality; gas and flaming coal; non-smoker; body plethysmograph.