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P299 A novel ileocolonic Crohn’s staging tool: the development and validation of an evidence-based, end-user informed radiological decision-aid

P. S. Morar*1,2, K. A. Wasmann3, A. C. T. Fareleira4, K. Sahnan1,2, S. O. Adegbola1,2, E. Mainta1, R. Ilangovan1, S. Arora2, N. Sevdalis5, K. Koysombat1, A. Hart1,2, D. Burling1, C. Edwards6, J. Warusavitarne1,2, A. Gupta1, W. A. Bemelman3, O. Faiz1,2

1St Mark's Hospital, London, UK, 2Imperial College London, London, UK, 3Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands, 4Centro Hospitalar S. Joao,, Porto, Portugal, 5King’s College, London, UK, 6South Devon NHS Foundation Trust,, Torbay, UK


Consensus guidelines emphasise the importance of multi-disciplinary team driven care for patients with complex Crohn’s disease (CD). There are, however, no clear definitions of complex ileocolonic CD beyond the presence or absence of preoperative intra-abdominal sepsis. This study aims to develop a staging instrument (The St Mark’s – Amsterdam tool) for complex ileocolonic CD based upon best evidence and end–user expert opinion and provide validation and reliability evidence for this tool.


Items for the staging tool were developed using literature review and semi-structured interviews. Validity was tested using surgical outcome measures which were reviewed against intra-operative and histopathologically (IoH) assigned stages. Reliability was tested against IoH assigned stages using cross-sectional imaging, which were used to provide an objective pre-operative stage for patients who have undergone ileocolonic resection.


A 4 stage tool was constructed.

The St Mark’s – Amsterdam tool consists of 4 stages of escalating disease advancement mirroring radiological features identified from literature review and end user opinion.

Validity testing with 324 patients demonstrated greater proportions of males (p < 0.005), patients without preoperative biologics (p < 0.05), patients with preoperative anaemia (p < 0.001), leukocytosis (p < 0.001), thrombocytosis (p < 0.001), hypoalbuminaemia (p = 0.001), CRP > 10 (p < 0.001), emergent surgery (p < 0.001), open surgery (p < 0.001), concomitant sigmoidectomy (p < 0.001), and pre-emptive stoma formation (p < 0.001), with increasing IoH stage, respectively. Eighty-four patients had preoperative cross-sectional imaging prospectively staged. Further testing demonstrated greater proportions of preoperative anaemia (p = 0.03), concomitant sigmoidectomy (p = 0.01), and pre-emptive stoma formation (p < 0.001), with increasing preoperative radiological stage. As an overall measure of morbidity, pre-emptive stoma formation and postoperative intra-abdominal septic complication were combined, demonstrating higher morbidity rates per increment IoH (p < 0.001) and radiological (p < 0.05) stage increase. Reliability was demonstrated, with 44(52%), 6(7%), 25(30%) and 9(11%) patients per increment radiological stage increase, and 26(39%), 14(21%), 20(30%), and 7(10%) per increment IoH stage increase, respectively (R = 0.8; p < 0.001).


This novel staging tool has been validated to show greater morbidity with increasing stage severity. It can reliably be used to preoperatively stage patients, estimate morbidity, and inform surgical decision-making through a tailored operative risk management approach. Further multi-centre prospective validation of this tool is required for both clinical and research purposes.