Table 4. Predictive clinical factors associated with the risk of internal fistula in Korean patients with Crohn’s disease.

		Univariate analysis a		Multivariate analysis b
		5-year cumulative rate (%)	P value	HR	95% CI	P value
Age at diagnosis (%)			0.354
	< 40 years	13.2		1.34	0.84–2.15	0.221
	≥ 40 years	12.7		1 (Ref)
Gender			0.211
	Male	12.5		0.81	0.59–1.12	0.207
	Female	14.9		1 (Ref)
Family history of IBD (%)			0.893
	Yes	8.7		0.89	0.33–2.41	0.818
	No	13.3		1 (Ref)
Disease location at diagnosis (%) c			0.009
	Any ileal involvement	14.2		1.89	1.17–3.06	0.009
	No involvement of ileum	8.5		1 (Ref)
Concomitant UGI disease (L4)			0.829
	Yes	14.2		0.99	0.59–1.66	0.958
	No	13.1		1 (Ref)
Interval of diagnostic delay (%)			0.040
	< 3 months	11.7		1 (Ref)
	3–6 months	12.5		1.01	0.63–1.64	0.957
	6–18 months	10.2		0.92	0.59–1.43	0.720
	≥ 18 months	19.4		1.62	1.12–2.33	0.011

HR, hazard ratio; CI, confidence interval; IBD, inflammatory bowel disease; UGI, upper gastrointestinal.

^acalculated by a Kaplan-Meier survival model.

^banalyzed by a multivariate Cox proportional hazards regression model.

^cDisease location and behavior were determined according to the Montreal classification.