Colectomy is a risk factor for venous thromboembolism in ulcerative colitis

Table 1 Characteristics of patients hospitalized for a ulcerative colitis flare, or undergoing a colectomy n (%)

Characteristics	Total cohort (n = 1020)	Elective colectomy (n = 329)	Emergency colectomy (n = 309)	Medically responsive (n = 382)	P value
Thrombosis					< 0.001
No	95.3 (972)	95.1 (313)	91.3 (282)	98.7 (377)
Yes	4.7 (48)	4.9 (16)	8.7 (27)	1.3 (5)
Age at Admission (tercile)					0.002
18-32	33.8 (345)	28.6 (94)	31.7 (98)	40.1 (153)
33-47	32.6 (333)	33.1 (109)	31.1 (96)	33.5 (128)
48+	33.5 (342)	38.3 (126)	37.2 (115)	26.4 (101)
Gender					0.022
Male	57.0 (581)	61.4 (202)	58.9 (182)	51.6 (197)
Female	43.0 (439)	38.6 (127)	41.1 (127)	48.4 (185)
Smoking					0.011
Current	9.8 (94)	7.9 (25)	7.7 (23)	13.3 (46)
Ex-smokers	33.0 (317)	30.5 (96)	39.0 (117)	30.1 (104)
Never	57.2 (549)	61.6 (194)	53.3 (160)	56.5 (195)
Missing (n)	n = 60	n = 14	n = 9	n = 37
Comorbidity
0 comorbidities	46.3 (472)	48.3 (159)	40.5 (125)	49.2 (188)	0.047
≥ 1 comorbidities	53.7 (548)	51.7 (170)	59.6 (184)	50.8 (194)
Primary sclerosing cholangitis					0.572
No	97.6 (996)	97.0 (319)	97.7 (302)	98.2 (375)
Yes	2.4 (24)	3.0 (10)	2.3 (7)	1.8 (7)
Ankylosing spondylitis or sacroiliitis					0.222
No	99.0 (1010)	99.7 (328)	98.4 (304)	99.0 (378)
Yes	1.0 (10)	0.3 (1)	1.6 (5)	1.0 (4)
Episcleritis, uveitis and iritis					0.603
No	98.9 (1009)	98.5 (324)	99.4 (307)	99.0 (378)
Yes	1.1 (11)	1.5 (5)	0.6 (2)	1.0 (4)
Disease duration, years					< 0.001
Median (IQR)	3 (0-9)	6 (2-14)	2 (0-7)	1 (0-6)
Missing (n)	n = 35	n = 18	n = 9	n = 8
Cancer/dysplasia					-
No	-	83.0 (273)	-	-
Yes		17.0 (56)
Extent of disease					< 0.001
Left-sided	29.4 (265)	23.5 (73)	20.9 (63)	44.5 (129)
Pancolitis	70.6 (637)	76.5 (237)	79.1 (239)	55.5 (161)
Missing (n)	n = 118	n = 19	n = 7	n = 92
Blood in Stool and Stool Frequency > 5/d1					< 0.001
No	27.0 (217)	46.4 (91)	18.9 (54)	22.3 (72)
Yes	73.0 (588)	53.6 (105)	81.1 (232)	77.7 (251)
Missing (n)	n = 215	n = 133	n = 23	n = 59
5-ASA2					< 0.001
No	33.1 (336)	28.0 (91)	26.9 (83)	42.4 (162)
Yes	66.9 (680)	72.0 (234)	73.1 (226)	57.6 (220)
Missing (n)	n = 4	n = 4
Prednisone2					< 0.001
No	31.3 (318)	16.6 (54)	22.0 (68)	51.3 (196)
Yes	68.7 (698)	83.4 (271)	78.0 (241)	48.7 (186)
Missing (n)	n = 4	n = 4
Azathioprine/6-mercaptopurine2					< 0.001
No	80.7 (820)	69.2 (225)	80.3 (248)	90.8 (347)
Yes	19.3 (196)	30.8 (100)	19.7 (61)	9.2 (35)
Missing (n)	n = 4	n = 4
Infliximab2					0.006
No	96.1 (976)	94.8 (308)	94.5 (292)	98.4 (376)
Yes	3.9 (40)	5.2 (17)	5.5 (17)	1.6 (6)
Missing (n)	n = 4	n = 4
Complication in hospital3					< 0.001
0 or Clavien I	80.2 (818)	79.9 (263)	64.1 (198)	93.5 (357)
Clavien II/III/IV	19.8 (202)	20.1 (66)	35.9 (111)	6.5 (25)
Postoperative heparin					0.641
No	6.9 (44)	6.4 (21)	7.4 (23)	-
Yes	93.1 (593)	93.6 (307)	92.6 (286)
Missing (n)	n = 1	n = 1
Heparin prophylaxis prior to surgery/discharge4					0.310
No	82.9 (572)	-	81.2 (251)	84.3 (321)
Yes	17.1 (118)		18.8 (58)	15.7 (60)
Missing (n)	n = 1			n = 1

¹Missing data is defined as missing on either the stool frequency, the presence of blood in stool, or both.

²Defined as medication used prior to or at the time of admission to hospital. No refers to no record of drug use in the medical chart.

³Complication was classified as Clavien ≥ II.

⁴Emergent colectomy - heparin prophylaxis in hospital prior to colectomy. Medically Responsive - heparin prophylaxis in hospital prior to discharge.

Table 2 Location of venous thromboembolism n (%)

Location of VTE	Total (n = 48)	Elective colectomy (n = 16)	Emergency colectomy (n = 27)	Medically responsive (n = 5)
Upper extremity	8 (17.4)	1 (6.3)	6 (22.2)	1 (20.0)
Lower extremity	9 (19.6)	3 (18.8)	6 (22.2)	0
Intra-abdominal	22 (45.8)	11 (68.8)	10 (37.0)	1 (20.0)
Pulmonary embolism	9 (18.8)	1 (6.3)	5 (18.5)	3 (60.0)

VTE: Venous thromboembolism.

Table 3 Independent predictors of venous thromboembolism for all ulcerative colitis patients; those admitted emergently to hospital and were medically responsive or underwent emergent colectomy; and those who underwent an emergent or elective colectomy

	Full cohort VTE (n = 1020)Adjusted OR (95%CI)	Emergent and medically responsive cohort VTE (n = 690)1Adjusted OR (95%CI)	Emergent and elective cohort VTE (n = 637)1Adjusted OR (95%CI)
Age, yr
18-32	1.00	1.00	1.00
33-47	1.56 (0.68-3.56)	2.44 (0.81-7.34)	1.35 (0.56-3.27)
≥ 48	1.63 (0.74-3.59)	2.29 (0.79-6.66)	1.65 (0.72-3.75)
Disease course
Medical responsive	1.00	1.00	Not applicable
Elective colectomy	3.69 (1.30-10.44)	Not applicable	1.00
Emergent colectomy	5.28 (1.93-14.45)	4.62 (1.66-12.88)	1.59 (0.82-3.07)
VTE prophylaxis2
No	Not applicable	1.00	1.00
Yes		2.24 (0.99-5.03)	1.38 (0.32-6.00)
In-hospital complication
No	1.00	1.00	1.00
Yes	2.68 (1.42-5.05)	2.80 (1.26-6.24)	2.53 (1.32-4.85)
Year	1.10 (1.01-1.20)	Not significant3	Not significant3

¹One patient was excluded in each of these cases due to missing data.

²VTE prophylaxis with anticoagulants (e.g., heparin) was assessed preoperatively/in-hospital for the emergent colectomy and medically responsive cohort, and postoperatively for the emergent and elective colectomy cohort. VTE prophylaxis was not modeled for the entire cohort.

³P value was > 0.1 when fitted into the regression model using stepwise selection. The following variables were tested in the multivariate model, but were not independent predictors in any of the models: sex, disease duration, comorbidities, extra-intestinal manifestations, extent of disease, blood in stool and frequency of bowel movements. 5-ASA: Azathioprine, prednisone, and infliximab; VTE: Venous thromboembolism.