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Multicentre endoscopist-blinded randomised clinical trial to compare two bowel preparations after a colonoscopy with inadequate cleansing: a study protocol
  1. Michael Sai Lai Sey1,2,
  2. Daniel von Renteln3,
  3. Richard Sultanian4,
  4. Cassandra McDonald2,
  5. Myriam Martel5,
  6. Alan Barkun5
  1. 1 Program for Experimental Medicine, Western University, London, Ontario, Canada
  2. 2 Division of Gastroenterology, London Health Sciences Centre, London, Ontario, Canada
  3. 3 Division of Gastroenterology, Centre Hospitalier de L’Universite de Montreal, Montreal, Quebec, Canada
  4. 4 Division of Gastroenterology, University of Alberta, Edmonton, Alberta, Canada
  5. 5 Division of Gastroenterology, McGill University, Montreal, Quebec, Canada
  1. Correspondence to Dr Michael Sai Lai Sey; msey2{at}


Introduction Inadequate bowel preparation is common and negatively impacts colonoscopy quality. The objective of this study is to compare two bowel preparation regimens in cleansing the colon after an index colonoscopy with failed bowel preparation.

Methods and analysis This is a phase III, multicentre, randomised clinical trial comparing two bowel preparation regimens after failure to adequately cleanse at the index colonoscopy. Regimen A consists of 4 L split-dose polyethylene glycol electrolyte solution (PEG-ELS) and Regimen B consists of 6 L split-dose PEG-ELS, both preceded by 15 mg of bisacodyl the day before the procedure along with a low-fibre diet 3 and 2 days before the procedure followed by a clear fluid diet starting the day before the procedure. The primary outcome is adequate bowel preparation, defined as a Boston Bowel Preparation Scale (BBPS) score of ≥6 with each segment score ≥2. Secondary outcomes include mean BBPS score, bowel preparation adequacy using the US Multi-Society Task Force on Colorectal Cancer definition, detection rate by polyp subtype, caecal intubation rate, mean Validated Patient Tolerability Questionnaire for Bowel Preparation score, subject willingness to repeat the preparation and faecal incontinence rate.

Ethics and dissemination The study will be conducted in accordance with Good Clinical Practice guidelines and local institutional standards. Study findings will be disseminated at an international gastroenterology conference and published in peer-reviewed journals.

Trial registration number NCT02976805; Pre-results.

  • gastroenterology
  • endoscopy
  • adult gastroenterology

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  • Contributors The protocol was written by MSLS with input from AB, RS, DvR and MM. All investigators critically revised iterations of the protocol and approved the final version. The manuscript was written by MSLS and critically revised by AB, RS, DvR, MM and CMD. All authors agree to the final version of the manuscript.

  • Funding This work was supported by the Academic Medical Organization of Southwestern Ontario (AMOSO), which provided salary support to MSLS, and Pharmascience, which provided PEG-ELS and bisacodyl in kind, and an arms-length unrestricted grant to support study expenses. As the commercial manufacturer of the study medications, Pharmascience provided limited administrative support for the Clinical Trials Application to Health Canada.

  • Competing interests Pharmascience were not involved in the study protocol and will not have access to study data nor its analysis, interpretation or decision to publish. MSLS has served as a speaker and participated in an advisory board for an unrelated topic for Pharmascience (ie, bile acid diarrhea). DvR has participated in an advisory board and has received research support from Pharmascience.

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

  • Patient consent for publication Not required.

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