Factors Predicting Loss of Remission in Crohn's Disease Patients in Endoscopic Remission in the Real World: Results From TARGET-IBD.

Background: There is limited evidence that histologic remission improves outcomes in Crohn's disease (CD). We aimed to characterize a cohort of patients with CD in endoscopic remission and explore factors associated with subsequent loss of remission (LOR).

Methods: In total, 4474 patients were enrolled in TARGET-IBD, a longitudinal, observational cohort study. Patients with a normal steroid-free colonoscopy (index) were defined as "in endoscopic remission" and were followed for LOR, defined as presence of inflammation, erosion, ulceration, or stricturing on a subsequent colonoscopy or commencement of steroids. Histologic activity was dichotomized using standard of care reports for active inflammation. Unadjusted and multivariable-adjusted Cox proportional hazards regression models were used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) of LOR in relation to independent variables.

Results: Of 658 patients with CD with steroid-free endoscopic remission, the majority were female (57%), white (83%), non-Hispanic (93%); 20% had ileal and 20% isolated colonic disease. Inflammatory (B1) disease was the most common phenotype (43%). Of these 658 patients, 257 (39%) had histologic inflammation on index colonoscopy. Histologic inflammation at index colonoscopy was associated with nearly twice the LOR risk (HR 1.96, 95% CI: 1.50-2.57) with median time to relapse of 1.20 years. Biologic use at index was associated with lower LOR risk (monotherapy, HR 0.61, 95% CI: 0.45-0.82; combination therapy, HR 0.43, 95% CI: 0.28-0.66).

Conclusions: Active histologic inflammation despite endoscopic remission, and lack of biologic use were independently associated with risk of subsequent LOR, providing evidence that histologic remission may impart improved outcomes in patients with CD.