A Multi-centre Endoscopist Blinded Randomized Clinical Trial to Compare Two Bowel Preparations After a Colonoscopy With Inadequate Bowel Preparation

PURPOSE

The purpose of this multi-centre randomized clinical trial is to compare two bowel preparation regimens for patients who fail to cleanse their colon during their index colonoscopy. Although many clinical trials already exist examining the optimal bowel preparation for colonoscopy in general, surprisingly none address patients who failed bowel preparation in the past. Failure to achieve bowel preparation is a result of complex factors, including underlying colonic dysmotility, co-morbidities, and concurrent medication usage and is rarely the result of patient non-compliance.(1) Given the frequency of inadequate bowel preparation, its negative impact on colonoscopy quality, the increased risk for an adverse event, and the need to repeat the procedure, an important public health need exists to address this question urgently.(1) This study will use many of the same methodology and investigators as an ongoing Canadian multicenter study titled, "The Bowel CLEAnsing: a National initiative ( B-CLEAN) " but on a smaller scale to answer this question.

BACKGROUND

Adequate bowel preparation is a prerequisite for high quality colonoscopy and is needed to maximize visualization of the colonic mucosa.(1-4) Unfortunately, inadequate bowel preparation is common and reported to occur in 4% to 17% of cases.(5-12) Procedures with poor preparation are more likely to be incomplete, have an adverse event, and are less likely to detect polyps.(1, 9, 13) Repeat colonoscopies within one year have shown a 36% miss rate for advanced adenomas in these patients.(12) Recognizing the importance of high quality colonoscopy, Cancer Care Ontario and other provincial health authorities now track adequacy rates for bowel preparation.

In cases of poor bowel preparation, the colonoscopy must be repeated, exposing patients to another invasive procedure and adding additional costs to the healthcare system. Although health economic data regarding colonoscopy utilization in Canada is sparse, an illustrative example from the United States is possible. Assuming 14.2 million screening colonoscopies are performed annually in the United States (14) of which 5% have inadequate bowel preparation (6, 8), a total of 710,000 colonoscopies have to be repeated at a cost of $763 million dollars, based on a per case cost of $1,075.(15) This is likely an underestimation of the true cost due to exclusion of non-screening colonoscopies in the calculation and the use of a low colonoscopy cost estimate based on the Nationwide Colonoscopy Program for the Uninsured.(15)