Epidemiology and clinical course of Crohn's disease: Results from observational studies

Table 2 Risk factors at diagnosis associated with surgery during follow-up analyzed by Cox regression (Solberg et al[30], with permission)

			Unadjusted			Adjusted
Variables at diagnosis	Number in analysis	Number with surgery (%)	HR	95% CI	P value	HR	95% CI	P value
Age
A1: < 40 yr	165	69 (42)	1	[Ref]	0.03	1	[Ref]	0.03
A2: ≥ 40 yr	72	16 (22)	0.5	0.3-0.9		0.5	0.3-0.9
Gender
Female	118	40 (34)	1	[Ref]	0.9	Not included
Male	119	45 (38)	1	0.7-1.6
Location
L1: Terminal ileum	64	38 (59)	1	[Ref]	< 0.001	1	[Ref]
L2: Isolated colonic	115	26 (23)	0.2	0.1-0.4		0.3	0.2-0.6	0.001
L3: Ileocolon	54	17 (32)	0.3	0.2-0.6		0.3	0.2-0.5	< 0.001
L4: Upper GI1	4	4 (100)	1.4	0.5-3.8		1.6	0.5-4.4	0.4
Behavior
B1: Inflammatory	147	32 (22)	1	[Ref]	< 0.001	1	[Ref]
B2: Stricturing	64	36 (56)	3.5	2.1-5.6		2.3	1.3-4.1	0.004
B3: Penetrating	26	17 (65)	4.9	2.7-8.8		5.4	3.0-9.9	< 0.001
Smoking status2
Never	103	38 (37)	1	[Ref]	0.2	Not included
Current < 10 cigarettes/d	57	18 (32)	0.8	0.4-1.4
Current > 10 cigarettes/d	36	18 (50)	1.9	0.8-2.6
Ex-smoker	35	11 (31)	0.8	0.4-1.6
Systemic steroids3
No	106	36 (34)	1	[Ref]	0.8	Not included
Yes	129	48 (37)	1.1	0.7-1.6

¹Difficult to conclude because of an insufficient number of patients;

²data unknown in 6 cases. There were none in the operated group;

³data unknown in 2 cases; There was one in the operated group. Ref: Reference variable; HR: Hazard ratio; CI: Confidence interval.