Prospective Randomized Controlled Trial Comparing Water Exchange Colonoscopy and Air Colonoscopy in a Community Based Setting

Brief Summary

Detailed Description

Screening colonoscopy with removal of pre-cancerous adenomas was recently shown to result in a 53% reduction in mortality from colon cancer. While this clearly validates the practice of screening colonoscopy, missed adenomas, especially in the proximal colon, defined as including cecum, ascending colon, and transverse colon, remains a concern. This was demonstrated in a study of 183 patients who underwent back-to-back colonoscopies. In this population the overall miss rate for adenomas was 24% with proximal adenomas missed more often (27%) than left colon adenomas (21%). Another study looked at 4192 patients in the SEER (Surveillance, Epidemiology, and End Results) Medicare database who developed "interval cancers", that is colon cancer in a patient who had a colonoscopy done in the previous 6-36 months. These interval cancers were predominantly in the proximal colon (Proximal 68%, Distal 19.5%, rectum 10.4%, and unspecified 2.1%). This also suggests that pre-cancerous lesions are being missed in the proximal colon. As such a method that can increase proximal adenoma detection rate would be a welcome change. One such emerging technique which shows promise for improving adenoma detection rate is water colonoscopy. In one of the early studies employing the water method a trend towards a higher ADR in the water method group was recognized (37% vs. 26%). The observation prompted a retrospective analysis of 1178 cases of screening and surveillance colonoscopy performed by a single endoscopist at the Sacramento VAMC, which showed an overall ADR (presence of at least one adenoma) of 27% with air colonoscopy whereas that for the water method colonoscopy was 35% (p=0.007). In a subsequent combined analysis of two prospective RCT of air vs. water colonoscopy for screening and surveillance using scheduled unsedated colonoscopy \[5\] and on-demand sedation \[6\], more patients were found to have at least one diminutive adenoma in the proximal colon in the water method group than in the air group (28% vs. 14%, respectively, p=0.0298). Another quasi randomized study of screening patients performed at Phoenix VAMC using high definition equipment confirmed a significantly higher overall ADR with the water method (n=177) compared with the air method (n=191) (57% vs. 46%) (p=0.03). The odds of detecting an adenoma was 81% higher with the water method (OR 1.81; 95% CI: 1.12-2.90) and independent of age, body mass index (BMI), current smoking and alcohol use, withdrawal time \& quality of bowel preparation. In the proximal colon ADR was significantly higher in patients examined with the water method than with air method (46% vs. 35%) (p=0.03), particularly for adenomas \<10 mm in size (38% vs. 25%) (p=007). These encouraging preliminary data reflect the potential benefits of water method colonoscopy. Our current research question is whether this benefit is seen in a community based population as opposed to the VA population which is mostly male and Caucasian. The investigators plan to perform a prospective, randomized controlled trial comparing proximal adenoma detection rate between a water exchange colonoscopy group and an air colonoscopy group. The investigators intend to employ scheduled sedation, instead of on-demand sedation, to continue the current protocol in place at our institution. Patients in both the study arms will undergo a split bowel preparation before colonoscopy.

Primary Outcomes

Secondary Outcomes

• Abdominal pressure by assistant during procedure(This will be collected at their procedure appointment which is expected to be 2 to 3 hours in length.)
• Sedation requirements(This will be collected at their procedure appointment which is expected to be 2 to 3 hours in length.)
• Total procedure time(This will be collected at their procedure appointment which is expected to be 2 to 3 hours in length.)
• Cecal intubation time(This will be collected at their procedure appointment which is expected to be 2 to 3 hours in length.)
• Total adenoma detection(Data collected when pathology is available, typically 3-10 days after the patient's procedure. Data is only collected once per patient.)
• Bowel preparation quality by Boston Bowel Prep Scale(This will be collected at the time of their procedure appointment which is expected to be 2 to 3 hours in length)
• Use of colonoscope stiffener during procedure(This will be collected at their procedure appointment which is expected to be 2 to 3 hours in length.)
• Reason for air insufflation, and length of colon when air insufflation started, while performing water colonoscopy(This will be collected at their procedure appointment which is expected to be 2 to 3 hours in length.)
• Patient perception regarding air and water colonoscopy(This will be collected at their procedure appointment which is expected to be 2 to 3 hours in length.)
• Advanced adenoma detection rate(Data collected when pathology is available, typically 3-10 days after the patient's procedure. Data is only collected once per patient)
• Patient position change during procedure(This will be collected at their procedure appointment which is expected to be 2 to 3 hours in length.)
• Length of colonoscope at time of cecal intubation(This will be collected at their procedure appointment which is expected to be 2 to 3 hours in length.)
• Procedure-related pain score(Data collected during and post procedure after recovery from sedation, which is usually within 1 hour post procedure)
• Type of polypectomy (cold biopsy/cold snare/snare cautery/need for submucosal injection/need for clip placement)(This will be collected at their procedure appointment which is expected to be 2 to 3 hours in length)
• Serrated polyp detection rate(This will be collected at the time of their procedure appointment which is expected to be 2 to 3 hours in length)
• Volume of water used during water colonoscopy(This will be collected at their procedure appointment which is expected to be 2 to 3 hours in length.)
• Body Mass Index (BMI)(This will be collected at their procedure appointment which is expected to be 2 to 3 hours in length)
• Post procedure recovery time(This will be collected at the time of their procedure appointment which is expected to be 2 to 3 hours in length)
• Smoking history(This will be collected at their procedure appointment which is expected to be 2 to 3 hours in length)
• Procedure time- morning versus afternoon(This will be collected at the time of their procedure appointment which is expected to be 2 to 3 hours in length)
• Alcohol consumption(This will be collected at their procedure appointment which is expected to be 2 to 3 hours in length)