Table 1.

Appendicectomy rates in ulcerative colitis patients and matched controls

Subject characteristics	Cases (n=307)	Controls (n=1016)	Crude OR	95% CI	p Value	Multivariate analysis OR	95% CI
Mean (SEM) age (y)	32.7 (0.85)	33.6 (0.38)			0.32
Sex
Female	48.9%	45.8%			0.34
Male	51.1%	54.2%
Smoking
Never smoker	54.4%	52.6%	1.00	(referent)		1.00	(referent)
Current smoker	3.3%	32.1%	0.10	0.05–0.19		0.10	0.05–0.19
Ex-smoker	42.3%	15.3%	2.71	2.03–3.64	<0.0001	3.29	2.38–4.56
	(n=307)	(n=896)
Appendicectomy
No	93.2%	76.9%	1.00	(referent)		1.00	(referent)
Yes	6.8%	23.1%	0.23	0.15–0.39	<0.0001	0.23	0.14–0.38
	(n=307)	(n=892)
Age at appendicectomy
None	93.2%	77.1%	1.00	(referent)		1.00	(referent)
≤20 y	3.3%	15.3%	0.17	0.09–0.34		0.16	0.08–0.32
>20 y	3.5%	7.6%	0.39	0.20–0.75	<0.0001	0.41	0.20–0.83