Clinical correlations of infliximab trough levels and antibodies to infliximab in South Korean patients with Crohn’s disease

Table 1 Demographics and baseline characteristics of the 138 South Korean patients in this study with Crohn’s disease who received infliximab treatment n (%)

Variables	Value
Male/female	90/48 (65.2/34.8)
Median age at diagnosis (IQR) (yr)	21 (19-27)
Median age at first infusion (IQR) (yr)	27 (22-33)
Median duration of disease prior to first IFX (IQR) (mo)	52 (13-91)
Indication for IFX treatment
Luminal	122 (88.4)
Perianal fistulizing	16 (11.6)
Median follow-up of IFX treatment (IQR) (mo)	47 (30-73)
Disease location at diagnosis
L1 (ileum)	19 (13.8)
L2 (colon)	9 (6.5)
L3 (ileocolon)	108 (78.3)
Not documented	2 (1.4)
Disease behavior at diagnosis
B1 (non-stricturing non-penetrating)	115 (83.3)
B2 (stricturing)	7 (5.1)
B3 (penetrating)	16 (11.6)
Perianal fistula at diagnosis
Active	36 (26.1)
Previous	26 (18.8)
Smoking status at diagnosis
Current smoker	26 (18.8)
Ex-smoker	9 (6.6)
Never smoker	103 (74.6)
Previous major abdominal surgery prior to first IFX	44 (31.9)
Concomitant immunomodulators
None	73 (52.9)
Azathioprine/6-mercaptopurine	64 (46.4)
Methotrexate	1 (0.7)

IQR: Interquartile range; IFX: Infliximab.

Table 2 Factors affecting the clinical activity of Crohn’s disease: Results of logistic regression analysis of each factor

	IFX-TL (μg/mL)	ATI levels (AU/mL)
Overall predictability (%)	82.0	75.9
Quiescent group (%)	82.9	96.3
Active group (%)	80.4	43.1
P value	< 0.001	0.003
Odds ratio (95%CI)	0.103 (0.045-0.236)	1.055 (1.018-1.093)

IFX-TL: Infliximab trough level; ATI: Antibody to infliximab.

Table 3 Factors affecting the clinical activity of Crohn’s disease: Results of logistic regression analysis of the 2 factors together

	IFX-TL (μg/mL)	ATI levels (AU/mL)
Overall predictability (%)	80.5
Quiescent group (%)	84.1
Active group (%)	74.5
P value	< 0.001	0.027
Odds ratio (95%CI)	0.150 (0.065-0.349)	1.028 (1.003-1.053)

IFX-TL: Infliximab trough level; ATI: Antibody to infliximab.