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Refinement and validation of the IDIOM score for predicting the risk of gastrointestinal cancer in iron deficiency anaemia
  1. Orouba Almilaji1,2,
  2. Carla Smith1,
  3. Sue Surgenor1,
  4. Andrew Clegg3,
  5. Elizabeth Williams1,
  6. Peter Thomas2,
  7. Jonathon Snook1
  1. 1Department of Gastroenterology, Poole Hospital NHS Foundation Trust, Poole, UK
  2. 2Clinical Research Unit, Bournemouth University, Bournemouth, Dorset, UK
  3. 3Health Technology Assessment Group, University of Central Lancashire, Preston, Lancashire, UK
  1. Correspondence to Dr Jonathon Snook; jonathon.snook{at}


Objective To refine and validate a model for predicting the risk of gastrointestinal (GI) cancer in iron deficiency anaemia (IDA) and to develop an app to facilitate use in clinical practice.

Design Three elements: (1) analysis of a dataset of 2390 cases of IDA to validate the predictive value of age, sex, blood haemoglobin concentration (Hb), mean cell volume (MCV) and iron studies on the probability of underlying GI cancer; (2) a pilot study of the benefit of adding faecal immunochemical testing (FIT) into the model; and (3) development of an app based on the model.

Results Age, sex and Hb were all strong, independent predictors of the risk of GI cancer, with ORs (95% CI) of 1.05 per year (1.03 to 1.07, p<0.00001), 2.86 for men (2.03 to 4.06, p<0.00001) and 1.03 for each g/L reduction in Hb (1.01 to 1.04, p<0.0001) respectively. An association with MCV was also revealed, with an OR of 1.03 for each fl reduction (1.01 to 1.05, p<0.02). The model was confirmed to be robust by an internal validation exercise. In the pilot study of high-risk cases, FIT was also predictive of GI cancer (OR 6.6, 95% CI 1.6 to 51.8), but the sensitivity was low at 23.5% (95% CI 6.8% to 49.9%). An app based on the model was developed.

Conclusion This predictive model may help rationalise the use of investigational resources in IDA, by fast-tracking high-risk cases and, with appropriate safeguards, avoiding invasive investigation altogether in those at ultra-low predicted risk.

  • gastrointestinal neoplasia
  • iron deficiency
  • endoscopy

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  • Contributors OA, AC, PT, EW and JS conceived and designed this study, and CS and SS collected the data. OA analysed the data and drafted the initial manuscript, and JS is the guarantor. All authors made significant contributions to the subsequent revision of the paper and approved the final version prior to submission.

  • Funding (1) Faecal immunochemical testing kits funded by Poole Hospital Gastroenterology Research Fund. (2) PhD studentship (OA) jointly funded by Poole Hospital Gastroenterology Research Fund and Bournemouth University. (3) AC part-funded by the National Institute for Health Research Applied Health Research Collaboration. The views expressed are those of the authors and not necessarily those of the NIHR or Department of Health and Social Care.

  • Disclaimer The views expressed are those of the authors and not necessarily those of the NIHR or Department of Health and Social Care.

  • Competing interests SS and EW have received honoraria for speaking at educational meetings sponsored by Pharmacosmos.

  • Patient consent for publication Not required.

  • Ethics approval A pilot study to explore the potential role of FIT—IDIOM-3 (ISRCTN No 18342140)—was undertaken with Research Ethics approval (IRAS No 201759).

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available on reasonable request. Data available from corresponding author.

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