Table 4B: GEE model (approach 2): Effect estimates for longitudinal change of lung function parameters in relationship with concentration (in 0.1 mg/m3) and duration (in quartz-years) of quartz dust exposure and co-variables. 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 | |||||||||
Quartz dust concentration* | -0.097 | 0.023 | < 0.001 | -0.069 | 0.023 | 0.003 | 0.099 | 0.293 | 0.735 |
Duration of exposure** | 0.000 | 0.003 | 0.897 | -0.002 | 0.003 | 0.537 | -0.039 | 0.039 | 0.324 |
Height (in cm) | 0.063 | 0.002 | < 0.001 | 0.049 | 0.002 | < 0.001 | -0.056 | 0.025 | 0.023 |
Weight (in kg) | -0.005 | 0.001 | < 0.001 | -0.005 | 0.001 | < 0.001 | -0.008 | 0.010 | 0.454 |
Age ≤ 25 | -0.036 | 0.004 | < 0.001 | -0.034 | 0.003 | < 0.001 | -0.118 | 0.039 | 0.002 |
Age > 25 | -0.029 | 0.004 | < 0.001 | -0.032 | 0.003 | < 0.001 | -0.186 | 0.036 | < 0.001 |
Non-German nationality*** | -0.162 | 0.045 | < 0.001 | -0.180 | 0.042 | < 0.001 | -1.197 | 0.487 | 0.014 |
Active smoker*** | -0.134 | 0.022 | < 0.001 | -0.082 | 0.021 | < 0.001 | 0.181 | 0.256 | 0.480 |
Former smoker*** | -0.100 | 0.031 | 0.001 | -0.015 | 0.028 | 0.584 | 0.903 | 0.347 | 0.009 |
Cumulative packyears | -0.004 | 0.001 | 0.003 | -0.008 | 0.001 | < 0.001 | -0.098 | 0.016 | < 0.001 |
Coking coal*** | 0.217 | 0.031 | < 0.001 | 0.050 | 0.030 | 0.090 | -2.398 | 0.342 | < 0.001 |
Custovit*** | 0.133 | 0.012 | < 0.001 | -0.020 | 0.011 | 0.068 | -2.475 | 0.167 | < 0.001 |
Vitalograph*** | 0.370 | 0.023 | < 0.001 | 0.397 | 0.023 | < 0.001 | 1.115 | 0.318 | < 0.001 |
Year of measurements | 0.013 | 0.004 | < 0.001 | 0.024 | 0.004 | < 0.001 | 0.264 | 0.044 | < 0.001 |
Statistics: Hazard ratio with standard error, Wald test: z-value, two-sided p-value. *unit: In 0.1 mg/m3; ** unit: Quartz-years; ***Reference: German nationality; gas and flaming coal; non-smoker; body plethysmograph.