Ileal and Rectal Ulcer Size Affects the Ability to Achieve Endoscopic Remission: A Post hoc Analysis of the SONIC Trial.

Introduction: It is unclear how baseline endoscopic characteristics in Crohn's disease (CD) affect the ability to achieve endoscopic remission (ER). We aimed to determine the endoscopic prognostic factors that influence achieving ER in CD.

Design: This post hoc analysis of SONIC (NCT00094458; YODA #2019-3980) evaluated baseline and week 26 endoscopy indices in 172 patients using the CD Endoscopic Index of Severity (CDEIS) and the Simple Endoscopic Score for CD. The impact of baseline ulcer depth and size on achieving week 26 ER was assessed using multivariate logistic regression models adjusted for confounders.

Results: The ER rate of ileal ulcers was significantly lower than ER rates throughout the colon (P < 0.0001). Ileal ulcers >2 cm were less likely to achieve ER compared with smaller ulcers {odds ratio (OR) 0.31 (95% confidence interval [CI] 0.11-0.89), P = 0.03}. Similarly, rectal ulcers >2 cm were associated with reduced odds of week 26 ER (OR 0.26 [95% CI 0.08-0.80], P = 0.02). Ulcer size in other colonic segments did not affect the achievement of week 26 ER. Deep ileal and rectal ulcers >2 cm compared with smaller or superficial ulcers were even less likely to achieve week 26 ER (ileum: OR 0.10, 95% CI 0.02-0.68, P = 0.02; rectum: OR 0.12, 0.02-0.82, P = 0.03). High baseline Simple Endoscopic Score for CD (≥16) or CDEIS scores (≥12) did not affect achieving week 26 ER.

Discussion: Patients with larger and deep ulcers in the ileum or rectum may have difficulty achieving ER. Overall degree of endoscopic inflammation as measured numerically by endoscopic scores does not affect the likelihood of achieving week 26 ER.