Comparative Efficacy of Water & Indigo Carmine vs. Water or Air Method on Adenoma Detection Rate (ADR) - a Randomized Controlled Trial (RCT)

Comparative Efficacy of Water & Indigo Carmine vs Water or Air Method

Adenoma detection rate (ADR) is a quality indicator of colonoscopy performed for colorectal cancer screening. Population studies have shown that traditional air colonoscopy fails to eliminate post screening colonoscopy cancers or cancer mortality in the proximal colon. The investigators aim to establish the superior effectiveness of combining chromoendoscopy with the water exchange method in detecting more proximal diminutive adenomas during screening colonoscopy in sedated Veterans. An improved adenoma detection rate associated with optical colonoscopy will minimize the risk of missed lesions. The improvement may translate into a remedy for the limitations of screening colonoscopy in the proximal colon, e.g. a higher adenoma detection rate may minimize the burden of post screening colonoscopy interval colorectal cancers among the veteran population.

1. Design: Prospective, single center, patient blinded, randomized controlled trial

2. Methods: Colonoscopy with traditional air insufflation, water exchange or water exchange plus indigocarmine to aid insertion of colonoscope; split dose bowel preparation; all patients will receive sedation; assessment of serum electrolytes level before and after colonoscopy

   1. Control method: Traditional air insufflation method.

   2. Study methods:

      • Water exchange method.
      • Water method combined with chromoendoscopy (0.008% indigo carmine).

3. Population to be studied Veterans between age 50 and 75 referred for first time screening colonoscopy

4. Unit(s) of analysis

   1. Primary outcome: overall adenoma detection rate.
   2. Secondary outcomes: patient demographic variable and procedure related measures.

5. Sampling strategy: all Veterans referred for screening colonoscopy will be offered enrollment in the study.

   1. Sample size calculation. A total of 480 subjects will be recruited and randomized with 160 in each group.

5. Subject recruitment: patients referred for screening colonoscopy come from three sources.

6. Description of base population and groups to be studied and method of randomization.

Veterans between age 50 and 75 referred for first time screening colonoscopy. After informed consent, assignment to control or study arm based on computer generated random number codes stored in pre-arranged opaque envelopes.

Inclusion Criteria:

• asymptomatic Veterans scheduled for first time screening colonoscopy and agree to be randomized will be enrolled.

Exclusion Criteria:

• patients who decline to be randomized, non screening cases.