Table 4.

Association between lung cancer and exposure to endotoxins by smoking status

	Never/light smokers*				Heavy smokers†
	Cases	Controls	OR‡	95% Cl	Cases	Controls	OR‡	95% Cl	p-Value Interaction§
	N	N			N	N
Exposure to endotoxins
Never¶	559	2090	1.00	Reference	1873	797	1.00	Reference
Ever**	92	505	0.64	(0.49 to 0.85)	373	152	0.87	(0.7 to 1.1)	0.01
Duration of exposure (years)
≤6	37	129	1.13	(0.75 to 1.7)	142	56	0.96	(0.67 to 1.36)
6–14)	24	119	0.72	(0.44 to 1.20)	87	30	1.15	(0.73 to 1.80)
>14–34	17	116	0.53	(0.30 to 0.96)	69	42	0.62	(0.40 to 0.95)
>34	13	141	0.26	(0.14 to 0.51)	72	24	0.81	(0.48 to 1.33)
Missing	1				3				0.01
Cumulative exposure (UE*years)¶
Quartile 1	43	109	1.66	(1.1 to 2.5)	126	56	0.97	(0.68 to 1.38)
Quartile 2	19	125	0.6	(0.34 to 1.01)	129	42	1.03	(0.7 to 1.52)
Quartile 3	21	128	0.57	(0.34 to 0.95)	66	33	0.61	(0.38 to 0.98)
Quartile 4	8	143	0.14	(0.06 to 0.32)	49	20	0.8	(0.45 to 1.4)
Missing	1				3	1			0.0003
Time since cessation of exposure (years)
≤5	10	143	0.28	(0.14 to 0.57)	62	29	0.88	(0.54 to 1.43)
>5–21	18	127	0.42	(0.23 to 0.75)	82	32	0.92	(0.59 to 1.44)
>21–39	27	112	1.02	(0.64 to 1.62)	121	55	0.9	(0.62 to 1.29)
>39	36	123	0.93	(0.6 to 1.43)	106	36	0.81	(0.53 to 1.24)
Missing	1				2				0.007
	p value§=0.007

*Never/light smokers were subjects with Cumulative Smoking Index (CSI)≤1. 

†Heavy smokers were subjects with CSI>1 

‡OR adjusted for age at interview, department, sex, number of job periods, education and occupational exposure to asbestos. The never exposed to endotoxins are always the reference group. 

§p Value for interaction between endotoxins and smoking status (using the likelihood ratio test). 

¶Never means having no job in work environment group potentially exposed to endotoxins. 

 **Ever means having held at least one job in work environment group potentially exposed to endotoxins.