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

Table 2 Gastric cancer risk in relation to tobacco use and alcohol drinking among men

	n	Person-years	Gastric cancer cases	RR	95%CI	P value1
Total	65553	900721
Bidi smoking						0.042
Never	31277	441290	35	1.0	Reference
Former	5830	70584	15	1.3	0.7-2.5
Current	25403	347383	62	1.6	1.0-2.5
Unknown	3043	41464	4	1.0	0.4-3.0
Cigarette smoking						0.265
Never	29205	398841	57	1.0	Reference
Former	5603	71488	18	1.4	0.8-2.4
Current	27835	390298	39	0.8	0.5-1.2
Unknown	2910	40093	2	0.4	0.1-1.7
Tobacco chewing						> 0.5
Never	42190	582656	73	1.0	Reference
Former	4383	54094	9	0.8	0.4-1.6
Current	18568	258317	34	0.9	0.6-1.4
Unknown	412	5653	0
Alcohol drinking						0.175
Never	33296	454553	51	1.0	Reference
Former	7857	98248	16	0.9	0.5-1.7
Current	24399	347905	49	1.3	0.9-2.0
Unknown	1	14	0

¹The P for trend (those in unknown categories were excluded). The model used for statistical analysis to obtain the RRs associated with tobacco and alcohol use was as follows: H = H_s exp(B_iX_i), where the background hazard, Hs, was stratified by attained age, calendar time, occupation and education, and X_i denotes categorical variables related to tobacco and alcohol use. Similar models were used in the analysis that produced the results presented in Tables 3-5.