Nested case-control study on the risk factors of colorectal cancer

Table 2 Results of univariate analysis for colon cancer (cases n = 84, controls n = 420)

factors	OR	95%CI	χ2	P
pork eating(y = 1, n = 0)	1.481		0.846	2.593	1.890	0.169
drining mixed water source* (y = 1, n = 0)	2.273	1.255	4.117	7.332	0.007
drining gutter water (y = 1, n = 0)	1.639	0.777	3.457	1.680	0.195
drining well water (y = 1, n = 0)	0.542	0.338	0.870	6.445	0.011
chronic diarrhea history(y = 1, n = 0)	2.018	1.003	4.060	3.871	0.049
constipaton history(y = 1, n = 0)	0.483	0.171	1.363	1.888	0.169
appendicitis history(y = 1, n = 0)	1.697	0.966	2.981	3.386	0.066
appendix operating history(y = 1, n = 0)	1.707	0.873	3.334	2.446	0.118
intestinal polyps history(y = 1, n = 0)	6.503	2.009	21.049	9.762	0.002

*drinking mixed water source refers to the subjects drinking different type of water sources through his/her lifetime, mostly drinking river water and gutter water. So is Table 2, Table 3 and Table 4