Methods

Clinical data on medical treatment, disease behavior and activity, CD-related complications and endoscopic activity, ER, respectively, were retrospectively obtained from clinical charts and endoscopy reports from patients’ visits at the IBD Centre Munich.

At each patient contact, the CDAI (Crohn’s Disease Activity Index) questionnaire was completed by patients and physicians.¹⁵

Early intervention with IFX was defined as start of IFX less than or equal to 24 months after first diagnosis of CD, late intervention with start of IFX more than 24 months after diagnosis of CD.

Primary outcome was defined as the ability of achieving ER at 24 months FU after start of IFX. CD-related complications were defined by the need for CD-related surgery within 24 months of FU, and the de novo development of stenoses and fistulas within 24 months of FU.

ER was defined as macroscopic absence of ulcerations seen in endoscopy.

For assessment of disease location, the Montreal classification was used.¹⁶

Information about IFX trough level were not available in our patient cohort. Information about intestinal stenoses and/or fistulas were based on endoscopic findings (luminal narrowing) and/or magnetic resonance enterography (criteria for obstructive disease: narrowing of the intrastenotic luminal diameter, prestenotic dilatation) and pelvic magnetic resonance imaging.¹⁷