A Novel Ileocolonic Crohn's Staging Tool: The Development and Validation of an Evidence-Based, End-User Informed Radiological Decision-Aid

Background: Consensus guidelines emphasise the importance of multidisciplinary team driven care for patients with complex Crohn's disease. There are, however, no clear definitions of complexity beyond the presence or absence of pre-operative intra-abdominal sepsis. This study aims to develop a staging instrument (The St Mark's - Amsterdam tool) for complex ileocolonic Crohn's disease based upon best evidence and end-user expert opinion. The secondary aim is to investigate validation and reliability evidence for this staging tool. Methods: Items for the staging tool were developed using a literature review and semi-structured interviews. Validity was tested using pre-operative, peri-operative and post-operative outcome measures which were reviewed against intra-operative and histopathologically and radiologically assigned stages. Reliability was tested against intra-operative and histopathologically assigned stages using magnetic resonance enterography (MRE) and computer tomographic enterography (CTE), which were used to provide an objective pre-operative stage for patients who have undergone ileocolonic resection. Findings: A 4-stage tool was derived including items detailing ileocolonic radiological disease: 1) predominantly inflammatory stricture; 2) predominantly fibrotic stricture; 3) fistulating; and 4) intra-abdominal abscess/collection. Validity testing demonstrated a greater proportions of pre-operative anaemia, concomitant sigmoidectomy and pre-emptive stoma formation, and/or post-operative intra-abdominal septic complications and/or Clavien-Dindo≥3, with increasing intra-operative and histopathologically and pre-operative radiological stage (p<0.05). Good reliability was demonstrated between pre-operative radiological stages and intra-operative and histopathologically assigned stages (R=0.8; p<0.001). Interpretation:This novel staging tool has been validated to show greater morbidity with increasing stage severity. It can reliably be used to pre-operatively stage patients, and inform surgical decision-making and estimate morbidity. It also allows for appropriate case mix adjustment from a research and outcomes reporting. Further multi-center prospective validation of this tool is required for both clinical and research purposes. Funding Statement: Morar, Sevdalis, Edwards and Faiz were funding by the Health Service Award, Crohn’s And Colitis UK (IBDHS/13/1). Nick Sevdalis’ research is funded by the NIHR via the ‘Collaboration for Leadership in Applied Health Research and Care South London’ (CLAHRC South London) at King's College Hospital NHS Foundation Trust, London, UK. Sevdalis is also part of King's Improvement Science, which is part of the NIHR CLAHRC South London and comprises a specialist team of improvement scientists and senior researchers based at King’s College London. King's Improvement Science is funded by King’s Health Partners (Guy’s and St Thomas’ NHS Foundation Trust, King’s College Hospital NHS Foundation Trust, King’s College London and South London and Maudsley NHS Foundation Trust), Guy’s and St Thomas’ Charity, the Maudsley Charity and the Health Foundation. Nick Sevdalis is also funded by the South London and Maudsley NHS Foundation Trust. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care. Edwards was funded by the South Devon Healthcare Charitable Fund (1052232). Declaration of Interests: NS is the Director of London Safety and Training Solutions Ltd, which provides quality and safety training and advisory services on a consultancy basis to healthcare organization globally. Ethics Approval Statement: Institutional approval from the local NHS hospital research and development committee was obtained (11/2014) prior to data collection. Data were obtained by cross-referencing two prospectively maintained databases within our institution from over a 10-year period [January 1, 2005 to January 1, 2015].