Multicenter case-control study of the risk factors for ulcerative colitis in China

Table 3 Smoking, breast feeding and medical history between ulcerative colitis and healthy controls

Variables	UC	Control	P value	OR	95%CI
Smoking
Nonsmoker	74.8%	74.5%
Current smoker
< 10 cigarettes per day	13.5%	13.4%	0.982	1.003	0.798-1.259
> 10 cigarettes per day	7.7%	8.9%	0.292	0.859	0.648-1.139
Ex-smoker	4.0%	3.2%	0.272	1.264	0.832-1.922
Breast feeding	46.5%	53.5%	0.628	1.080	0.790-1.477
Infectious diarrhea	14.1%	9.3%	0.000	1.610	1.256-2.064
Appendectomy	3.4%	3.2%	0.737	0.929	0.602-1.432
NSAIDs	9.0%	7.2%	0.209	1.269	0.875-1.841
Measles	9.4%	8.2%	0.286	1.162	0.882-1.532
Parasite	15.7%	11.2%	0.053	1.486	0.946-1.926
Oral contraceptive	6.3%	5.2%	0.082	2.734	0.880-8.495

UC: Ulcerative colitis; NSAIDs: Nonsteroidal anti-inflammatory drugs; OR: Odds ratio.