Impact of a Predictive Score of Bowel Preparation Quality in Clinical Practice


This is a single center randomized controlled trial to compare the colon cleansing quality determined by the Boston Bowel Preparation Scale achieved by two strategies in patients with high risk of poor colon cleansing defined as those patients with a score> 1.225 following a predictive score previously published: one group will receive an intensified split-dose 4 L polyethylene glycol solution (PEG) plus bisacodyl and 3 days of fiber-free diet and the other group a split-dose 2 L PEG solution with ascorbic plus bisacodyl and 1 day of fiber-free diet. Patients with a score ≤ 1.225 will receive a split-dose 2 L PEG solution with ascorbic plus bisacodyl and 1 day of fiber-free diet.

Full Title of Study: “Intensive High-volume Bowel Cleansing Regimen Versus Low-volume Bowel Regimen in Patients With a High Risk of Poor Colonic Cleansing Following a Validated Predictive Score”

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Parallel Assignment
    • Primary Purpose: Other
    • Masking: Single (Investigator)
  • Study Primary Completion Date: October 21, 2019

Detailed Description

This is a prospective, randomized, single-blind phase IV study in which all outpatients scheduled for a colonoscopy will be given a different bowel cleansing strategy (conventional or intensified) according to a scoring system already validated in the investigator's center, designed with variables independently associated with poor bowel cleansing, constipation, abdominal/pelvic surgery, comorbidity and to be on antidepressant treatment. According to this system, a score equal to or less than 1.225, predicts with a high confidence (negative predictive value = 88%) a suitable cleansing quality with a standard preparation protocol. Therefore, these subjects will be advised of a conventional preparation (low fiber diet the day before the examination and low volume preparation consisting of 2 L of PEG with ascorbic acid). Subjects with a score greater than 1.225 will be randomized to receive an intensive bowel preparation (low fiber diet three days prior to colonoscopy and large bowel preparation consisting of 4 L PEG with bisacodyl) or a conventional one (low fiber diet the day before the examination and 2 L of PEG with ascorbic acid). The choice of low-volume preparation as a control is supported by the absence of significant differences in quality of cleanliness in patients with a score > 1.225 among patients prepared with high or low volume and that low volume preparation appears to improve tolerance and compliance. A researcher will offer to participate in the study to all outpatients with a scheduled colonoscopy, who meet all the inclusion criteria and none of the exclusion criteria. The researchers will explain the purpose of the study and will ask to sign the informed consent. They will give verbal and written information on the bowel preparation strategy. Thus, according to the allocation group, participants must comply with a large volume cleansing strategy or a conventional one. For patients with a low score (≤ 1.225) a conventional preparation will be recommended. Patients must complete a baseline questionnaire at the inclusion visit and another questionnaire at the colonoscopy visit. The hypothesis of the study is that in patients with a high risk of poor bowel preparation, the large bowel based preparation strategy is superior to the conventional bowel preparation in achieving an acceptable bowel cleansing assessed by a validated scale (Boston Bowel Preparation Score).


  • Drug: polyethylene glycol
    • The experimental arm will take 4 L polyethylene glycol solution (PEG) in split dose plus bisacodyl and 3 days of fiber-free diet
  • Drug: polyethylene glycol plus ascorbic acid
    • The control arm will take 2 L polyethylene glycol solution (PEG) plus ascorbic acid in split dose plus 1 day of fiber-free diet

Arms, Groups and Cohorts

  • Experimental: Large volume based preparation
    • This strategy will consist of split dose 4 L polyethylene glycol plus 10 mg bisacodyl plus 3 days of fiber-free diet.
  • Active Comparator: Low volume based preparation
    • This strategy will consist of split dose 2 L polyethylene glycol plus Ascorbic acid plus 1 day of fiber-free diet

Clinical Trial Outcome Measures

Primary Measures

  • Boston Bowel Preparation Scale
    • Time Frame: 8 months
    • This scale goes from 0 (no preparation) to 3 points (excellent preparation) in the three segments of the colon (proximal, transverse and distal). The maximum score is 9 points

Secondary Measures

  • Proportion of polyps detected in each arm
    • Time Frame: 8 months
    • Number of polyps in one arm/total of polyps detected
  • Tolerance to bowel preparation
    • Time Frame: 8 months
    • It will be subjective and assessed by a visual analog scale (0 very bad, 10 excellent)

Participating in This Clinical Trial

Inclusion Criteria

  • Age ≥ 18 years – Outpatient colonoscopy – Willing to participate (informed consent signed). Exclusion Criteria:

  • Intestinal perforation – Poorly controlled arterial hypertension (HTAS> 180 HTAD> 100) – Congestive heart failure – NYHA III-IV – Acute hepatic failure – End-stage renal disease (creatinine <15 ml / min dialysis or pre-dialysis) – Pregnancy or breastfeeding – Known hypersensitivity reaction to drug components – Phenylketonuria or Glucose-6-phosphate dehydrogenase deficiency – Dementia with difficulty in intake of Preparation – Past history of poor bowel preparation colonic cleanliness – Inability to follow the instructions

Gender Eligibility: All

Minimum Age: 18 Years

Maximum Age: N/A

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • Hospital Universitario de Canarias
  • Provider of Information About this Clinical Study
    • Sponsor
  • Overall Official(s)
    • Goretti Hernandez, MD, Principal Investigator, Hospital Universitario de Canarias

Citations Reporting on Results

Gimeno-García AZ, Hernandez G, Aldea A, Nicolás-Pérez D, Jiménez A, Carrillo M, Felipe V, Alarcón-Fernández O, Hernandez-Guerra M, Romero R, Alonso I, Gonzalez Y, Adrian Z, Moreno M, Ramos L, Quintero E. Comparison of Two Intensive Bowel Cleansing Regimens in Patients With Previous Poor Bowel Preparation: A Randomized Controlled Study. Am J Gastroenterol. 2017 Jun;112(6):951-958. doi: 10.1038/ajg.2017.53. Epub 2017 Mar 14.

Gimeno-García AZ, Baute JL, Hernandez G, Morales D, Gonzalez-Pérez CD, Nicolás-Pérez D, Alarcon-Fernández O, Jiménez A, Hernandez-Guerra M, Romero R, Alonso I, Gonzalez Y, Adrian Z, Carrillo M, Ramos L, Quintero E. Risk factors for inadequate bowel preparation: a validated predictive score. Endoscopy. 2017 Jun;49(6):536-543. doi: 10.1055/s-0043-101683. Epub 2017 Mar 10.

Dik VK, Moons LM, Hüyük M, van der Schaar P, de Vos Tot Nederveen Cappel WH, Ter Borg PC, Meijssen MA, Ouwendijk RJ, Le Fèvre DM, Stouten M, van der Galiën O, Hiemstra TJ, Monkelbaan JF, van Oijen MG, Siersema PD; Colonoscopy Quality Initiative. Predicting inadequate bowel preparation for colonoscopy in participants receiving split-dose bowel preparation: development and validation of a prediction score. Gastrointest Endosc. 2015 Mar;81(3):665-72. doi: 10.1016/j.gie.2014.09.066. Epub 2015 Jan 17.

Hassan C, Fuccio L, Bruno M, Pagano N, Spada C, Carrara S, Giordanino C, Rondonotti E, Curcio G, Dulbecco P, Fabbri C, Della Casa D, Maiero S, Simone A, Iacopini F, Feliciangeli G, Manes G, Rinaldi A, Zullo A, Rogai F, Repici A. A predictive model identifies patients most likely to have inadequate bowel preparation for colonoscopy. Clin Gastroenterol Hepatol. 2012 May;10(5):501-6. doi: 10.1016/j.cgh.2011.12.037. Epub 2012 Jan 10.

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