Water-aided Colonoscopy vs Air Insufflation Colonoscopy in Colorectal Cancer Screening

Study Overview
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Brief Summary
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The degree of protection afforded by colonoscopy against proximal colorectal cancer (CRC) appears to be related to the quality of the procedure, and the incomplete removal of lesions has been shown to increase the subsequent risk of developing a colon cancer. Some studies suggest that small polyps with advanced histology are more common in the right than in the left colon (right colon proximal to splenic flexure, left colon distal to the splenic flexure). The average size of polyps in the right colon with advanced pathology or containing adenocarcinoma was ≤9 mm, whereas in the left colon their average size was >9 mm, P<0.001. Inadequate prevention of right-sided CRC incidence and mortality may be due to right-sided polyps with advanced histology or that harbor malignancy. These presumptive precursors of cancer are smaller and possibly more easily obscured by residual feces, and more likely to be missed at colonoscopy. Water-aided colonoscopy (WAC) can be subdivided broadly into two major categories: water immersion (WI), characterized by suction removal of the infused water predominantly during the withdrawal phase of colonoscopy, and water exchange (WE), characterized by suction removal of infused water predominantly during the insertion phase of colonoscopy. In some reports WE appeared to be superior to both WI and air insufflation colonoscopy (AI) in terms of pain reduction and adenoma detection, particularly for <10 mm adenomas in the proximal colon. In this multicenter, double-blinded randomized controlled trial (RCT) we test the hypothesis that that WE, compared to AI and WI, will enhance overall Adenoma Detection Rate (ADR) in CRC screening patients. Confirmation of the primary hypothesis will provide evidence that WE enhances the quality of screening colonoscopy. We also hypothesize that WE may be more effective in detecting proximal colon adenomas than WI and AI, particularly <10 mm adenomas, thus increasing proximal colon ADR and proximal colon ADR <10 mm. Confirmation of secondary hypotheses will provide justification for further testing that WE may provide a strategy to improve prevention of colorectal cancer by increasing detection of adenomas in screening colonoscopy. Unlike previous reports of single colonoscopist studies, the insertion and withdrawal phases of colonoscopy will be done by different investigators. The second investigator will be blinded to the method used to insert the instrument, thus eliminating possible bias about procedure related issues. Several secondary outcomes will also be analysed.

Detailed Description
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Design: Prospective double-blinded multicenter randomized controlled trial. Methods: Colonoscopy with Air Insufflation, Water Immersion, Water Exchange to aid insertion of colonoscope; split dose bowel preparation. Sedation available at the start of the procedure or on-demand. Control method: Air insufflation colonoscopy. Study methods: Water Immersion colonoscopy, Water Exchange colonoscopy. Population: Consecutive 50 to 70 year-old screening patients. After informed consent, assignment to control or study arms based on computer generated randomization list with block allocation and stratification. Primary outcome: overall Adenoma Detection Rate. Secondary outcomes: proximal colon ADR, Mean Adenomas resected per Procedure (MAP), cecal intubation rate and time, total procedure time (including biopsy and/or polypectomy), maximum pain during colonoscopy assessed during insertion and at discharge, the need for sedation/analgesia and its dosage. In addition loop reduction maneuvers, position changes, abdominal compression, the amount of infused and suctioned water during insertion and withdrawal, and patients willingness to repeat the examination will be evaluated.

Official Title
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A Randomized, Controlled Trial Comparing Air Insufflation, Water Immersion and Water Exchange for Adenoma Detection Rate in Screening Colonoscopy

Conditions
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Colorectal Cancer, Colorectal Adenomas, Colorectal Polyps, Pain

Intervention / Treatment
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* Other: Air insufflation method.
* Other: Water Immersion method.
* Other: Water Exchange method.


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: consecutive screening patients Exclusion Criteria: previous colonoscopy within 5 years surveillance colonoscopy previous colorectal surgery indication for a proctosigmoidoscopy or bidirectional endoscopy history of inflammatory bowel disease patient refusal or inability to provide informed consent inadequate consumption of bowel preparation

Ages Eligible for Study
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Minimum Age: 50 Years
Maximum Age: 70 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Air insufflation method.<br>Colonoscopy performed in the standard fashion, with the minimal air insufflation required to aid insertion and allowing for washing as needed. Considered to be standard procedure. | Other: Air insufflation method.<br>* Air insufflation colonoscopy.<br>|
| Experimental: Water Immersion method.<br>Infusion of water during the insertion phase of colonoscopy mainly to open the colonic lumen and progress to the cecum immersed in the water environment thus created, without attempting to clear the colon contents. Residual air in the colon will not be removed. Infused water and residual feces will be suctioned back predominantly during withdrawal. Insufflation not used until the cecum is reached. It will be allowed only 3 times and no more than 10 seconds each time (ITT failure if >3) if the lumen cannot be seen. Withdrawal phase done using air insufflation. | Other: Water Immersion method.<br>* Water Immersion during insertion, air insufflation during withdrawal.<br>|
| Experimental: Water Exchange method.<br>Insufflation not used until the cecum is reached. Infusion of a sufficient amount of water to render the lumen of the colon a slit to progress with the colonoscope. Part of the infused water will be constantly suctioned back exchanging clean for dirty or hazy water. Air pockets will be always aspirated to collapse the lumen. After cecal intubation as much residual water as possible will be aspirated before beginning the withdrawal phase. During withdrawal residual water and feces will be suctioned. Withdrawal phase done using air insufflation. | Other: Water Exchange method.<br>* Water Exchange during insertion, air insufflation during withdrawal.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Adenoma Detection Rate. | Proportion of subjects with at least one adenoma of any size. | 18 months. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Proximal colon Adenoma Detection Rate. | Proportion of subjects with at least one adenoma of any size in the proximal colon. | 18 months. | 
| Proximal colon <10 mm Adenoma Detection Rate. | Proportion of subjects with at least one adenoma <10 mm in the proximal colon. | 18 months. | 
| Mean adenomas resected per procedure. | Total number of adenomas resected per subject. | 18 months. | 
| Cecal intubation rate. | Cecal intubation will be defined as passage of the tip of the colonoscope beyond the ileocecal valve so that the medial wall of the cecum proximal to the ileocecal valve will be observed. | 1 hour. | 
| Cecal intubation time. | Cecal intubation time will be defined as the time for passage of the colonoscope from the rectum to the cecum. | 1 hour. | 
| Total procedure time. | Total procedure time (including time required for polyp resection or biopsy). | 1 hour. | 
| Maximum pain score recorded during insertion phase of colonoscopy. | Pain will be measured on a visual analogue scale (VAS) with a score 0=absence of pain, 1-2=simply discomfort, 10=the worst possible pain. Before the procedure, an endoscopic nurse will explain the VAS scoring system to the patient. Patient will be informed that the request for pain information is not to remind that the examination should be uncomfortable, but to let the colonoscopist be alerted to the need to use maneuvers to minimize discomfort (e.g. loop reduction, removal of colonic content, abdominal compression and/or change in patient position). At regular intervals during colonoscopy (e.g. every 60 seconds) patients will be asked about discomfort or pain. The responses will be recorded, and the maximum pain score noted. | 1 hour. | 
| Pain score at discharge. | After the procedure and at discharge from the Endoscopy Unit, an assistant nurse blinded to the procedure will ask patients about maximum pain during insertion phase of the procedure using the same VAS when neither the endoscopist nor the assistant nurse who performed the colonoscopy will be present. Patients will be asked to quantify the degree of pain experienced and to place a mark over the VAS accordingly. | 1 hour. | 
| Need for sedation/analgesia and its dosage | All patients will be offered sedation for the procedure. Patients can accept or decline the medication. If they accept, the procedure will be started with the administration of 2 mg of Midazolam intravenously (minimal sedation). If the patient will choose on-demand sedation, minimal sedation will be offered when pain score reaches ≥2 on the VAS. Patients can accept or decline the offered medication. If they accept, minimal sedation will be administered as described above. To avoid bias by the colonoscopist, sedation medication will be administered based on the patients' confirmation that the pain is no longer tolerable, and not at the discretion of the colonoscopist. The colon segment in which patients requests sedation will be recorded. If additional medication will be required despite the abovementioned maneuvers and/or minimal sedation, it will be provided according to local standards and it will be recorded. | 1 hour. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Water-aided colonoscopy, Water Immersion, Water Exchange, On-demand sedation, Unsedated colonoscopy, Adenoma detection rate, Mean adenomas per procedure