Histologic and Endoscopic Findings Are Highly Correlated in a Prospective Cohort of Patients With Inflammatory Bowel Diseases

Background and aims: The advantages of endoscopic vs histologic assessments of inflammation in inflammatory bowel disease remain unclear. We compared endoscopic and histologic inflammation in a prospective cohort. Furthermore, in patients with discordant findings, we compared the ability of endoscopy vs histology to predict disease course.

Methods: Ulcerative colitis (UC) or Crohn's disease (CD) patients underwent routine colonoscopies with intestinal biopsies, which included ratings of inflammation severity. Tetrachoric correlation analysis between the endoscopic and histologic inflammation ratings was performed. In postsurgical CD patients, major adverse outcomes (MAOs) were recorded.

Results: The analysis included 749 patients (60.2% CD patients), with 2807 biopsied segments. We found high concordance between endoscopist and pathologist inflammation ratings (0.84, 95% confidence interval, 0.81-0.87, p < 0.0001). Only 12.5% of biopsied segments exhibited microscopic inflammation without endoscopic inflammation. Neo-terminal ileum (neo-TI) biopsies exhibited the highest discordance; UC colonic biopsies had the highest concordance. Postsurgical CD patients who completed the 48-month follow-up (n = 138) were included in the survival analysis. The probability of MAO-free survival was significantly higher in patients with a Rutgeerts score of i0 at baseline than in those with higher scores. Microscopic inflammation in the neo-TI did not predict a higher risk of MAOs (p = 1.00).

Conclusions: In a real-world setting, endoscopic inflammation predicted histologic inflammation with high accuracy. In patients with a Rutgeerts score of i0, microscopic inflammation in neo-TI biopsies did not predict more aggressive disease behavior over the next 4 years. These results have implications for the design of clinical trials, suggesting the use of endoscopic healing as an endpoint.