IBD Advanced Colorectal Neoplasia (aCRN) Risk Assessment Tool: Online Calculator
Overview of the IBD aCRN Risk Assessment Tool
The IBD advanced colorectal neoplasia (aCRN) risk-assessment tool is designed for healthcare providers, to estimate the 5-year risk of aCRN, which includes high-grade dysplasia (HGD) and colorectal cancer (CRC), in patients with inflammatory bowel disease (IBD). This tool complements the 2025 British Society of Gastroenterology (BSG) Guidelines on Colorectal Surveillance in Inflammatory Bowel Disease by incorporating a dynamic, evidence-based prediction model for patients meeting the following criteria:
- Adults aged 18–75 with a confirmed diagnosis of IBD (ulcerative colitis, Crohn’s disease, or unclassified IBD) involving at least 30% of the colon.
- Includes patients with primary sclerosing cholangitis (PSC).
- Disease duration ≥7.5 years, or any duration in the presence of PSC.
This calculator takes about five minutes to complete.
Tool Limitations:
Limited data is available for extremes of age and patients undergoing more than 30 follow-up years of surveillance. Results for these populations may be less accurate until additional data are collected. While the tool is not perfect, it remains a valuable resource for clinicians and patients to better understand individual risks of aCRN.
This tool cannot accurately estimate risk of aCRN for people who have the following health conditions:
- Familial colorectal cancer syndromes e.g. Lynch syndrome or Serrated Polyposis Syndrome
- Personal history of advanced colorectal neoplasia (HGD or colorectal cancer)
- Family history of colorectal cancer in a first degree relative
- Colonic Strictures in IBD
- Paediatric onset of IBD
Resources on aCRN Risk in IBD:
Risk Calculator
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About the Calculator
The aCRN risk-assessment tool employs a dynamic prediction model developed using a landmarking approach based on Cox proportional hazards modelling. This method, applied by researchers at the University of Utrecht in Netherlands to develop the current model, enables risk assessment at multiple follow-up time points by integrating changes in patient characteristics and risk factors over time. Such dynamic modelling is critical in IBD, where the risk of aCRN evolves as disease duration and severity progress.
Scientific basis:
The model was developed using data from six large, diverse cohorts across Canada, the Netherlands, the UK, and the USA. This included 3,731 patients, contributing a total follow-up of 26,336 patient-years. Robust performance metrics were demonstrated during internal-external cross-validation, with a c-statistic of 0.74 for 5-year risk prediction and consistently good calibration across the cohorts.
Implications for Future Research:
Future research should focus on external validation, ensuring that the tool performs well in diverse healthcare settings, including community-based practices, to confirm its real-world applicability. Moreover, integrating risk estimates with surveillance intervals supported by expert and patient consensus, such as those outlined in the 2025 BSG guidelines, can enhance clinical usability. Further iterations of the model may also include additional predictors to refine accuracy and improve its utility for a broader range of patients.
This tool will be updated periodically as new data or research becomes available. In addition, it may prove useful to researchers who are designing clinical intervention studies.
References:
- East JE*, Gordon M*, Nigam GB§, Sinopoulou V§, Bateman AC, Din S, Iacucci M, Kabir M, Lamb CA, Wilson A, Al Bakir I, Dhar A, Dolwani S, Faiz O, Hart A, Hayee B, Healey C, Leedham SJ, Novelli M, Raine T, Rutter MD, Shepherd NA, Subramanian V, Vance M, Wakeman R, White L, Trudgill N†, Morris J†. British Society of Gastroenterology Guidelines on Colorectal Surveillance in Inflammatory Bowel Disease: An Update from 2010. Gut (in press).
- Wijnands AM, Penning de Vries BBL, Lutgens MWMD, Bakhshi Z, Al Bakir I, Beaugerie L, Bernstein CN, Chang-Ho Choi R, Coelho-Prabhu N, Graham TA, Hart AL, Ten Hove JR, Itzkowitz SH, Kirchgesner J, Mooiweer E, Shaffer SR, Shah SC, Elias SG, Oldenburg B; Dutch Initiative on Crohn and Colitis (ICC). Dynamic Prediction of Advanced Colorectal Neoplasia in Inflammatory Bowel Disease. Clin Gastroenterol Hepatol. 2024;22:1697-1708. doi: 10.1016/j.cgh.2024.02.014.