3-day vs. 1-day Low Residue Diet Influence in Colonoscopy Preparation and Patient Tolerability

Colonoscopy is one of the most common methods for the diagnosis and treatment of lower gastrointestinal tract diseases and provides a unique opportunity to identify early neoplastic lesions.

Adequate bowel preparation is important for optimal colonoscopy. New bowel-cleansing regimens, study of patient-related risk factors to fail a proper preparation and diet adaptations have been studied recently.

A low residue diet is the standard in the day before the colonoscopy. Some endoscopists prescribe this dietary plan for a 3-day period prior to the exam, although no study compared the recommended 1-day versus 3-day diet regime, or the influence in bowel preparation results.

The aim of this project is to determine if the use of a 3-day low residue diet improves bowel preparations results and the influence in patient tolerability and adherence.

a. Study type: prospective, randomized, single-blinded trial:

i. Prospective inclusion of ambulatory patients;

ii. Randomization by computer generated tables;

iii. Allocation concealment by sealed, opaque envelopes;

iv. Patient not blinded to diet;

v. Endoscopist blinded to the diet followed by each patient.

b. Patient selection: Consecutive series of patients scheduled for total colonoscopy; Exclusion criteria: inpatients, sedation, urgent procedures, colonoscopies not intended to reach the caecum, patient with previous partial colectomy.

c. Sample Size:

i. 412 individuals; 2 groups of 206 patients

ii. Primary goal: to achieve a reduction from 15 to 5% of inappropriate preparation result; The Boston Bowel Preparation Scale (BBPS) will be used as grading system. Inappropriate is defined as total BBPS \< 6 or \< 2 in any segment. The chosen scale is the most systematically validated and appropriate for the clinical setting. iii.Both groups, from a community-based outpatient ambulatory center, used the same split dose regimen with Polyethylene glycol (PEG).Patients were instructed to drink 3 L of PEG preparation on the afternoon of the day prior to the exam and 1 L four hours before the scheduled exam time. All the exams scheduled for morning period. Assuming a normal distribution, a power of 90% and a type I error of 0.05, the calculated sample size for each group was 188; allowing a 10% dropout rate, the sample size is 206 per group (412 patients overall); Groups: Group A: 3-day low residue diet + split dose preparation; Group B: 1-day low residue diet + split dose preparation

d. Endoscopist:

Exams to be conduct by 5 board-certified gastroenterologists and 2 supervised fellows in training; All physicians were trained in the use of BBPS by online training available at http://cori.org/bbps/, and have been using the BBPS for at least 3 months.

e. Data collection methods: form sheet filled by the endoscopist and patient opinion regarding the assigned bowel preparation protocol.

f. Analyzed variables:

i. Primary outcome: BBPS score

ii. Secondary outcome: Patient assessment of tolerance and acceptance of the preparation and diet

iii. Tertiary outcome: polyp detection rate (PDR), polyp location, size and configuration; adenoma detection rate (ADR), cecum intubation rate

iv. Other variables and patients characteristics (age, gender, chronic medication, risk factors for inappropriate preparation), withdrawal time.

g. Statistical analysis: T-test for groups comparing quantitative variables with normal distribution (primary outcome); Qui square test for groups comparing proportions (secondary and tertiary outcomes)

Eligibility Criteria:
Inclusion Criteria:

* Consecutive series of patients scheduled for total colonoscopy
* Signed informed consent

Exclusion Criteria:

* inpatients
* sedation
* urgent procedures
* colonoscopies not intended to reach the caecum
* patient with previous partial colectomy.