Higher infliximab and adalimumab trough levels are associated with fistula healing in patients with fistulising perianal Crohn’s disease

Table 2 Differences between patients on infliximab with and without fistula healing

	Patients with fistula healing (n = 48)	Patients without fistula healing (n = 18)	P value
Median age, yr (IQR)	33.0 (28.0-38.0)	43.5 (34.3-57.3)	0.005
Female gender, n (%)	20 (41.7)	8 (44.4)	0.839
Mean weight, kg (SD)	82.2 (19.4)	76.5 (15.7)	0.378
Mean BMI, kg/m2 (SD)	28.5 (5.0)	26.7 (3.8)	0.318
Median age at diagnosis of Crohn’s disease (IQR)	26.0 (20.75-30.5)	30.0 (24.0-43.0)	0.121
A1, n (%)	1 (2.1)	1 (5.6)	-
A2, n (%)	41 (85.4)	11 (61.1)	-
A3, n (%)	4 (8.3)	5 (27.8)	-
Current smoker, n (%)	8 (16.7)	4 (22.2)	0.696
Location
Ileal, n (%)	14 (29.2)	2 (11.1)	-
Colonic, n (%)	19 (39.6)	7 (38.9)	-
Ileocolonic, n (%)	11 (22.9)	4 (22.2)	-
No luminal disease, n (%)	2 (4.2)	2 (11.1)	-
Upper gastrointestinal involvement, n (%)	3 (6.3)	1 (5.6)	-
Stricturing, n (%)	7 (14.6)	3 (16.7)	0.822
Penetrating, n (%)	5 (10.4)	2 (11.1)	0.927
Median duration on anti-TNF agent, wk (IQR)	153.0 (86.0-285.0)	95.5 (40.25-322.75)	0.387
Dose escalated anti-TNF therapy, n (%)	15 (31.3)	4 (22.2)	-
Concurrent steroids, n (%)	0 (0.0)	1 (5.6)	-
Concurrent aminosalicylates, n (%)	4 (8.3)	1 (5.6)	0.219
Combination with immunomodulator, n (%)	35 (72.9)	11 (61.1)	0.522
Methotrexate, n (%)	6 (12.5)	2 (11.1)	0.937
6-mercaptopurine, n (%)	6 (12.5)	3 (16.7)	0.597
Azathioprine, n (%)	23 (47.9)	6 (33.3)	0.368
Concurrent allopurinol, n (%)	9 (18.8)	1 (5.6)	0.197
Mean albumin, g/L (SD)	40.3 (4.7)	40.7 (4.6)	0.590
Median CRP, mg/L (IQR)	2.1 (1.0-4.5)	5.5 (1.1-8.7)	0.094
Median trough level, mg/L (IQR)	6.4 (3.8-9.5)	3.0 (0.3-6.2)	0.003
Detectable antibody, n (%)	3 (4.3)	6 (33.3)	0.004

ADA: Adalimumab; BMI: Body mass index; CRP: C-reactive protein; IFX: Infliximab; IQR: Interquartile range; SD: Standard deviation; TNF: Tumor necrosis factor.