Table 3.

Stratified analyses of lung cancer risk.

Stratification by smoking status
	Never smokers* (N=41 case-control sets)	Former smokers* (N=96 case-control sets)	Current smokers (N=51 case-control sets)
Detectable	1	1	1
Non-detectable	9.25 (0.56, 154.09) p=0.12	2.53 (0.33, 19.65) p=0.38	NA1
Ln concentration	1.42 (0.85, 2.40) p=0.18	1.26 (0.89, 1.76) p=0.19	2.08 (0.97, 4.49) p=0.06
Stratification by age at enrollment
	<=65 years† (N=94 case-control sets)	>65 years† (N=94 case-control sets)
Detectable	1	1
Non-detectable	14.79 (1.34, 163.36) p=0.03	5.11 (0.58, 44.96) p=0.14
Ln concentration	1.77 (1.15, 2.72) p=0.01	1.30 (0.91, 1.86) p=0.15
Stratification by duration of follow-up
	<94.64 months§ (N=94 case-control sets)	>=94.64 months§ (N=94 case-control sets)
Detectable	1	1
Non-detectable	2.81 (0.37, 21.24) p=0.32	23.49 (1.80, 307.18) p=0.02
Ln concentration	1.13 (0.80, 1.59) p=0.48	1.93 (1.23, 3.03) p=0.04

Odds ratios (ORs) and 95% confidence intervals (CI) reported as OR (95% CI), OR for non-detectable status and ln of concentration are mutually adjusted and further adjusted for matching variables.

Ln concentration, log-transformed concentration.

¹Among smokers, only one subject has non-detectable levels.

^*P for interaction between never/former smoking status and non-detectable levels = 0.46, P for interaction between never/ever smoking status and non-detectable levels = 0.62

^*P for interaction between never/former smoking status and ln of blood concentrations = 0.69,

^*P for interaction between never/ever smoking status and ln of blood concentrations = 0.92.

^†P for interaction between age group and non-detectable levels = 0.46

^†P for interaction between age group and ln of blood concentrations = 0.99

^§P for interaction between follow-up duration and non-detectable levels = 0.57

^§P for interaction between follow-up duration and ln of blood concentrations = 0.06