Colon Cleansing Quality of Polyethylene Glycol Compared With Polyethylene Glycol Plus Ascorbic Acid.

Study Overview
=================
Brief Summary
-----------------
The purpose of the study is to assess whether a low volume polyethylene glycol (PEG) plus ascorbic acid based bowel preparation for colonoscopy is not inferior to a large volume polyethylene glycol preparation in subjects with past history of poor bowel preparation

Detailed Description
-----------------
Two key quality indicators for colonoscopy are the cecal intubation rate and the percentage of neoplastic lesions detected. Both factors are associated with adequate bowel cleansing. Poor cleansing ranged from 5% to 30% across studies, negatively affecting the efficiency of colonoscopy. The most important factor associated with poor colonic preparation is the past history of poor bowel preparation. However, there are no recommendations on the proper type of preparation in those patients. In two non-randomized studies inadequate cleansing in the second colonoscopy ranged from 9.8% to 23%. Randomized studies comparing high volume (3-4 liters) with low volume (2 liters) PEG preparations, which are better tolerated by patients, are therefore needed before making any recommendations in this regard.

Official Title
-----------------
Randomized Clinical Trial to Evaluate the Colon Cleansing Quality of Polyethylene Glycol Compared With Polyethylene Glycol Plus Ascorbic Acid in Patients With Past Poor Colonic Preparation

Conditions
-----------------
Colonoscopy Preparation

Intervention / Treatment
-----------------
* Drug: Polyethylene glycol 4000
* Drug: Macrogol 3350 plus ascorbic acid


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Age> 18 years Outpatients with a history of past poor bowel prep, defined according to the Boston scale as a score less than 5. Signed informed consent Exclusion Criteria: paralytic ileus, intestinal obstruction, megacolon, poorly controlled hypertension (systolic pressure> 180, dyastolic pressure> 100), congestive heart failure, acute liver failure, end stage renal disease (dialysis or pre-dialysis), New York Heart Association class III-IV, pregnancy, diagnosis of phenylketonuria, diagnosis of glucose-6-phosphate dehydrogenase deficiency, dementia. History of poor preparation in the previous colonoscopy, colon resection, less than 75% intake of the bowel preparation in the index colonoscopy, refusal to participate in the study, patients in whom a new colonoscopy is not indicated despite a poor bowel preparation(i.e. ileal Crohn disease with poor large bowel preparation), lack of compliance with the bowel preparation schedule.
Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Diagnostic
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: High volume<br>Two 5 mg bisacodyl tablets It is a stimulant laxative with local action. Polyethylene glycol 4000: 16 envelopes (70 g of powder each). It includes electrolytes and sodium sulfate. | Drug: Polyethylene glycol 4000<br>* - Polyethylene glycol 4000: 16 envelopes (70 g of powder each). It includes electrolytes and sodium sulfate. These substances make PEG metabolically inert, achieving a suitable osmotic balance, despite having a high molecular weight. The preparation passes along the gastrointestinal tract without causing net absorption of fluid or electrolytes. It is routinely used in clinical practice for bowel cleansing, before abdominal surgery, barium enema and other colorectal and genitourinary tract tests. Participants will divide the whole doses in 4 liters of water taking half the day before the examination starting at 20.00 h and the other half at 6.00 pm on the day of the examination.<br>|
| Experimental: Low volume<br>Two 5 mg bisacodyl tablets, taken in the same way as for the high volume group. Macrogol 3350 plus ascorbic acid: 4 envelopes, 2 containing 112 g polyethylene glycol and electrolytes and 2 with 2 g of ascorbic acid. | Drug: Macrogol 3350 plus ascorbic acid<br>* - Macrogol 3350 plus ascorbic acid: 4 envelopes, 2 containing 112 g polyethylene glycol and electrolytes and 2 with 2 g of ascorbic acid. The properties of the polyethylene glycol are the same as those mentioned previously, while ascorbic acid generates an osmotic gradient potentiating the effect of polyethylene glycol. It is used routinely as a bowel prep. Participants will divide the doses in 2 liters of water taking half the day before (112 g of PEG and an 11 g of ascorbic acid) the examination at 20.00 h and the other half at 6.00 pm on the day of the examination<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Colon cleansing | Colon cleansing will be assessed just after colonoscopy by the endoscopist in charge of performing the examination and afterwards images were reviewed by a the staff of endoscopists for validation (30 days). For assessing colon cleansing a validated scale (Boston scale) will be used. | 30 days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Tolerance of bowel preparation | It will be assessed by using a visual analog scale colon | Tolerance will be assessed just before colonoscopy by a research assistant | 
| Detection of colorectal neoplasia | Detection rate of adenoma and colorectal cancer will be assessed for both groups (low volume and high volume preparation) | 14 months | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
colon cleansing, bowel preparations; polyethyleneglycol