Objectives: Discrepancies between inflammatory bowel disease (IBD) endoscopic/histological extent are documented at diagnosis. It is unclear whether these differences persist through disease course, with potential impact on categorization and management. We aimed to analyze the progression of disease over a 3-year period.
Methods: Patients younger than 17 years, diagnosed between 2010 and 2013 at Southampton Children's Hospital and followed-up for 3 years were eligible. Primary outcome was disease extent at diagnosis and follow-up. Data are presented as percentage of patients undergoing endoscopy. Paris classification (PC) and PC using histological, rather than endoscopic disease, were determined.
Results: One hundred and twenty-five patients were included, 66 boys; Crohn's disease (CD) 74, ulcerative colitis (UC) 40, IBD unclassified (IBDU) 11. All had endoscopy at diagnosis. One hundred and two patients underwent ≥1 repeat endoscopies.Disease extent reduced from diagnosis to first follow-up endoscopy for both endoscopic and histological disease extent (CD/UC/IBDU, all P < 0.00006). Histological extent remained greater than endoscopic in CD with significant differences in stomach, ileum, and large bowel at all follow-up points (P = < 0.045). Endoscopic matched histological extent in UC/IBDU. Applying a modified PC resulted in significant changes for CD (L3 27.4%-53.2%, P = 0.006, L3 + L4A 21%-50%, P = 0.001, and upper gastrointestinal disease 50%-80.6%, P = 0.0006) but not UC. CD height (-0.37 to -0.25) and weight (-1.09 to -0.19) standard deviation scores increased from diagnosis to follow-up.
Conclusions: Histological disease is greater than endoscopic extent at diagnosis and during follow-up in CD, although not in UC/IBDU. Classification of disease extent in CD should be based on both endoscopic and histological criteria.