Table 5:

Logistic Regression: Predictors of Abdominal and Perianal Surgery in CD patients (N = 400)

CD ONLY: Abdominal and Perianal Surgery
	Estimate	Standard Error	Z value	Pr(>|z|)
Age	-0.002	0.01	-0.13	0.90
Gender	0.31	0.29	1.07	0.29
Disease Duration	0.08	0.02	4.37	1.27e-05
Disease Behavior (Reference = inflammatory)
Stricturing	2.59	0.35	7.42	1.19e-13
Fistulizing and Penetrating	3.35	0.41	8.19	2.54e-16
Fistulizing/Penetrating and Stricturing	3.71	0.51	7.26	3.81e-13
Fistulizing/Penetrating and Inflammatory (n = 1)	14.3	882.7	0.02	0.99
Disease Location	0.82	0.43	1.91	0.06
Smoking Status
Former	0.25	0.47	0.53	0.60
Current	-0.48	0.59	-0.83	0.41
CHRNA5 rs16969968	-0.31	0.30	-1.02	0.31
CHRNA5 rs16969968 * Smoking Status
Former	-0.02	0.47	-0.05	0.96
Current	1.06	0.63	1.67	0.1

AIC: 355.69. In the logistic regression without interaction between smoking and CHRNA5 genotype, the main effects of smoking and CHRNA5 genotype alone were not significant either.