Table 2.

The prevalence of ever exposure to passive smoking and its association with Crohn’s disease and ulcerative colitis

Passive smoking	Crohn’s disease				Ulcerative colitis
	Case (%)	Control (%)	Unadjusted OR, 95% CI	Adjusteda OR, 95% CI	Case (%)	Control	Unadjusted OR, 95% CI	Adjusteda OR, 95% CI
China
Ever	62.0	54.3	1.37 (0.84–2.22)	1.40 (0.85–2.29)	62.8	54.3	1.42 (0.75–2.69)	1.48 (0.75–2.90)
Never	38.0	45.7	1	1	37.2	45.7	1	1
India
Ever	12.0	8.6	1.44 (0.36–5.76)	1.53 (0.33–7.09)	7.7	8.6	0.88 (0.28–2.75)	1.04 (0.29–3.66)
Never	88.0	91.4	1	1	92.3	91.4	1	1
USA
Ever	51.0	56.0	0.82 (0.57–1.18)	0.87 (0.60–1.28)	48.3	56.0	0.74 (0.50–1.09)	0.69 (0.46–1.04)
Never	49.0	44.0	1	1	51.7	44.0	1	1

^aAdjusted for active smoking status at IBD diagnosis and sex