Water-aided Colonoscopy vs Air Insufflation Colonoscopy in Colorectal Cancer Screening
Condition: Colorectal Cancer; Colorectal Adenomas; Colorectal Polyps; Pain
MeSH terms: Colorectal Neoplasms; Adenoma
Study type: Interventional

Summary: 
      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: 
      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.
    

Intervention name(s): Air insufflation method.; Water Immersion method.; Water Exchange method.
Intervention type(s): Other; Other; Other
Intervention description(s): Air insufflation colonoscopy.; Water Immersion during insertion, air insufflation during withdrawal.; Water Exchange during insertion, air insufflation during withdrawal.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Investigator)
Keywords: Water-aided colonoscopy; Water Immersion; Water Exchange; On-demand sedation; Unsedated colonoscopy; Adenoma detection rate; Mean adenomas per procedure