Smoking increases the risk of extraintestinal manifestations in Crohn's disease

Table 1 Patient characteristics at first diagnosis and during follow-up n (%)

		All patients	Crohn's disease	Ulcerative colitis	P value
		n = 257	n = 161 (62.6)	n = 96 (37.4)	RR (95%CI)
Sex: male/female		121 (47.1)/136 (52.9)	71 (44.1)/90 (55.9)	50 (52.1)/ 46 (47.9)	0.22
EIM at first diagnosis	At least 1 EIM	91 (35.4)	69 (42.9)	21 (21.9)	< 0.001; RR = 1.96 (1.30-2.95)
New EIM during follow-up	At least 1 EIM	115 (44.7)	79 (49.1)	36 (37.5)	0.07
EIM at any point of observation	At least 1 EIM	163 (63.4)	114 (69.9)	49 (30.1)	0.001; RR = 1.39 (1.11-1.73)
	> 1 EIM	24 (14.5)	18 (15.5)	6 (12.2)	0.39
New EIM during follow-up		94 (36.6)	64 (39.8)	30 (31.3)	0.17
EIM resolved during follow-up		64 (66.0)	47 (64.4)	17 (70.8)	0.63
Disease phenotype at first diagnosis	Crohn's disease		Terminal ileum (L1) 56 (34.8)
			Colon (L2) 40 (24.8)
			Terminal ileum and colon (L3) 61 (37.9)
			Upper GI tract (L4) 2 (1.2)
	Ulcerative colitis			Proctitis 36 (37.5)
				Left-sided colitis 23 (24.0)
				Pancolitis 29 (30.2)1

¹Not applicable in 8 patients. EIM: Extraintestinal manifestation; GI: Gastrointestinal.

Table 2 Different extraintestinal manifestations at first diagnosis n (%)

	All patients n = 257	Crohn's disease	Ulcerative colitis	P value
Arthralgia	40 (16.3)	26 (17.8)	14 (14.6)	0.60
Arthritis	18 (7.3)	13 (8.9)	5 (5.2)	0.50
Ocular manifestation	5 (2.1)	2 (1.4)	3 (3.1)	0.63
Active sacroiliitis	12 (4.9)	11 (7.6)	1 (1.0)	0.06
Pyoderma gangrenosum	2 (0.8)	1 (0.7)	1 (1.0)	0.95
Erythema nodosum	7 (2.7)	7 (4.9)	0	0.002
PSC	1 (0.4)	0	1 (1.0)	0.4

PSC: Primary sclerosing cholangitis.

Table 3 Different extraintestinal manifestations during the observation period n (%)

	All patients n = 257	Crohn's disease	Ulcerative colitis	P value
Arthralgia	89 (34.6)	56 (34.8)	33 (34.4)	1.0
Arthritis	23 (8.9)	13 (8.1)	10 (10.4)	0.65
Ocular manifestation	19 (7.4)	13 (8.1)	6 (6.2)	0.81
Active sacroiliitis	7 (2.7)	5 (3.1)	2 (2.1)	1.0
Pyoderma gangrenosum	0
Erythema nodosum	1 (0.4)	1 (0.6)	0	1.0
PSC	1 (0.4)	0	1 (1.0)	0.4

PSC: Primary sclerosing cholangitis

Table 4 Univariate analysis and logistic regression model (outcome variable = extraintestinal manifestation during observation period) for Crohn's disease n (%)

Variable	Category (n)	With EIM	Univariate analysis		Logistic regression analysis
			P value	RR (95%CI)	P value	RR (95%CI)
Surgery	Yes (27)	19 (70.4)	0.015	2.93 (1.20-7.16)	0.015	3.19 (1.26-8.02)
	No (134)	60 (44.8)
Smoking	Yes (55)	33 (60.0)	0.046	1.96 (1.01-3.74)	0.023	2.36 (1.13-4.93)
	No (106)	46 (43.4)
Age	≤ 40 yr (126)	62 (49.2)	0.026	2.40 (1.01-5.23)	0.011	2.94 (1.28-6.76)
	> 40 yr (35)	22 (62.9)
Family history	Yes (35)	20 (57.1)	0.510	1.29 (0.61-2.75)	0.260	1.59 (0.71-3.55)
	No (126)	64 (50.8)
Sex	Female (90)	46 (51.1)	0.870	0.9 (0.49-1.69)	0.070	0.52 (0.25-1.05)
	Male (71)	38 (53.3)

EIM: Extraintestinal manifestation.

Table 5 Univariate analysis for ulcerative colitis n (%)

Variable	Category (n)	With EIM	Univariate analysis
			P	RR (95%CI)
Sex	Female (46)	17 (37.0)	0.92	0.96 (0.42-2.20)
	Male (50)	19 (38.0)
Pancolitis1	Yes (29)	12 (41.4)	0.49	1.38 (0.55-3.44)
	No (59)	20 (33.9)
Surgery	Yes (6)	5 (83.3)	0.03	9.52 (1.06-85.08)
	No (90)	31 (34.4)
Family history	Yes (5)	1 (20.0)	0.65	0.39 (0.04-3.66)
	No (90)	25 (38.9)
Smoking	Yes (19)	7 (36.8)	0.80	1.14 (0.42-3.13)
	No (77)	29 (37.7)
Age	≤ 40 y (67)	27 (40.3)	0.39	0.67 (0.26-1.68)
	> 40 y (29)	9 (31.0)
Immunosuppressive therapy	Yes (27)	11 (40.7)	0.71	1.18 (0.48-2.95)
	No (68)	25 (36.8)

¹Not applicable in 8 patients. EIM: Extraintestinal manifestation.