Gastric cancer risk in relation to tobacco use and alcohol drinking in Kerala, India - Karunagappally cohort study

Table 3 Gastric cancer risk in relation to bidi smoking among men

	Person-years	Gastric cancer cases	RR	95%CI	P value1
Bidis smoked per day					0.012
Never	441290	35	1.0	Reference
Former	70584	15	1.3	0.7-2.5
1-4	40768	4	1.0	0.4-2.8
5-14	131494	20	1.4	0.8-2.5
15-24	105359	23	1.9	1.1-3.4
≥ 25	67303	15	1.7	0.9-3.2
Unknown	43924	4	1.0	0.3-2.8
Duration of bidi smoking					0.036
Never	441290	35	1.0	Reference
1-14	141330	10	1.3	0.6-2.8
15-29	123435	14	1.1	0.6-2.1
30-44	84545	30	2.0	1.2-3.5
≥ 45	68393	23	1.6	0.9-3.0
Unknown	41728	4	1.0	0.4-3.0
Age at start of bidi smoking					0.161
< 18	64800	14	2.0	1.0-3.9
18-22	172714	32	1.8	1.1-2.9
≥ 23	109709	16	1.3	0.7-2.5
Never	441290	35	1.0	Reference
Unknown	41624	4	0.0
Years since quitting bidi smoking					0.424
Current smokers	347383	62	1.0	Reference
< 5	28435	6	0.9	0.4-2.0
5-9	18058	5	1.1	0.5-2.9
≥ 10	23055	4	0.6	0.2-1.7
Never	441290	35	0.6	0.4-1.0
Unknown	42500	4	0.6	0.2-1.7

¹The P for trend (those in unknown category were excluded).