Background In 5–15% of children diagnosed with inflammatory bowel disease (IBD), the histological picture at diagnosis doesn’t fit in with either ulcerative colitis (UC) or Crohn's disease (CD) and is classified as unclassified-IBD (IBDU) or indeterminate colitis.¹ The aim of this prospective study is to determine whether IBDU evolves into UC or CD.

Methods Prospective data has been collected on all the newly diagnosed children with IBD at the only regional paediatric gastroenterology centre covering southwest of England. All patients suspected of IBD had upper and lower gastrointestinal endoscopy and MRE scan or barium meal as recommended by BSPGHAN.² Patients diagnosed with IBDU during 2004–2011 were included in the study and followed up for a minimum of 2 years (range 2–9 years). The patient notes were reviewed in 2013 and any changes in diagnosis recorded.

Results 333 children were diagnosed with IBD between 2004–2011: 193 (58%) had CD, 115 (34.5%) UC and 25 (7.5%) IBDU. Age (mean) at diagnosis: 10.2 years (IBDU), 11.5 years (CD) and 11.6 years (UC). 7/26 (27%) IBDU had pan-colitis and 19/26 (63%) had patchy or left-sided colitis on lower gastrointestinal endoscopy. After 2 to 9 years, IBDU evolved into CD in 5 patients (22.8%), UC in 3 (13.6%) and remained IBDU in 14 patients (63.6%). Latest data was unavailable for 3 (11.6%) because of transfer to distant adult services. ANCA was positive in 3 out of 4 patients whose diagnosis was revised as CD.

Conclusion This large prospective study has documented that over 2–9 years, 22.8% IBDU evolved into CD, 13.6% into UC and 63.6% remained IBDU. IBDU patients tended to be younger at diagnosis. Positive ANCA was not an useful predictive marker. This has implications for management of IBDU patients especially where surgical treatment is considered.

References

1. De Bie CL, et al. (2012). J Pediatr Gastroenterol Nutr. 54(3):374-80

2. Sandhu BK, et al. (2010). J Pediatr Gastroenterol Nutr. 50:S1-S13