Cox regression models: Hazard ratios for CWP ≥ 0/1 and cumulative exposure to respirable quartz, or mean concentration and exposure duration, and covariables. No. of subjects = 1369, No. of cases = 72.

Table 4: Cox regression models: Hazard ratios for CWP ≥ 0/1 and cumulative exposure to respirable quartz, or mean concentration and exposure duration, and covariables. No. of subjects = 1369, No. of cases = 72.

Covariable	Haz. ratio	Std. err	95% Conf. interval		P > \|z\|
Approach 1
Cumulative quartz exposure (0.1 mg/m³-years)	1.083	0.022	1.038	1.130	< 0.001
Height (in cm)	0.991	0.020	0.953	1.031	0.659
Weight (in kg)	1.021	0.008	1.004	1.038	0.012
Non-german nationality^**	1.588	0.335	0.823	3.065	0.168
Coking coal^**	2.043	0.272	1.199	3.480	0.009
Active smoker^**	1.681	0.324	0.890	3.175	0.109
Former smoker^**	0.899	0.401	0.410	1.973	0.791
Approach 2
Mean concentration of quartz (0.1 mg/m³)	1.861	0.392	0.862	4.016	0.114
Exposure duration (in year)	1.134	0.038	1.053	1.221	0.001
Height (in cm)	0.990	0.020	0.952	1.030	0.619
Weight (in kg)	1.021	0.008	1.004	1.038	0.014
Non-german nationality^**	1.542	0.337	0.796	2.987	0.199
Coking coal^**	2.131	0.281	1.229	3.697	0.007
Active smoker^**	1.579	0.323	0.838	2.977	0.158
Former smoker^**	0.834	0.400	0.380	1.828	0.650

Statistics: Hazard ratio with standard error; Wald test: z-value, Two-sided p-value. ^**Reference: German nationality; Gas and flaming coal; Non-smoker.