Randomized Controlled Trial Comparing Adult to Pediatric Colonoscope in Obese Patients.
Phase: NA
Conditions: Obesity (Body Mass Index &Amp;Amp;gt;30 kg/m2), Screening Colonoscopy
Sponsor: Cleveland Clinic Florida

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Randomized controlled trial comparing adult to pediatric colonoscope in obese patients. 
NCT 06776913

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Randomized controlled trial comparing adult to pediatric colonoscope in obese patients. 
Corresponding author: 
Akram I Ahamd
Email: ahmada5@ccf.org 
Address: 2950 Cleveland Clinic Blvd, Weston, FL 33331 
 
Principal Investigator:  
Asad Rahman 
Email: rahmanf3@ccf.org
Address: 2950 Cleveland Clinic Blvd, Weston, FL 33331 
Background
A colonoscopy is a routine procedure performed daily for various purposes, 
including colon cancer screening. Over time, colonoscopes have evolved and 
now come in different sizes, diameters, and flexibility levels. The choice of 
colonoscope typically depends on the endoscopist's preference, and 
anecdotal experience, with all types of instruments considered standard 
practice.
Several patient characteristics can make routine colonoscopy more 
challenging, such as diverticulosis and a history of previous surgeries, 
especially in the pelvic area. These challenging cases might influence the 
provider to choose one instrument over another, although there is a general 
lack of evidence demonstrating the superiority of specific colonoscopes in 
certain situations.
Obesity is one of the challenges encountered during routine colonoscopy. A 
retrospective study showed no difference in the performance of adult and 
pediatric scopes when matching the population's BMI. However, providers 
tend to choose adult scopes for higher BMI patients in unmatched 
populations. We designed this study to evaluate if adult and pediatric 
colonoscopes perform differently in obese patients, which both are 
considered standard practice in the study population.

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Study objective.
The objective of this equivalence trial is to evaluate whether pediatric and 
adult colonoscopes achieve similar success rates in obese patients 
undergoing colonoscopy. Patients will be randomly assigned in a 1:1 ratio. 
The primary endpoint is the success rate of colonoscope completion without 
switching instruments (defined in the main protocol).  
Study hypothesis. 
There is no significant difference between adult and pediatric colonoscopes 
in the evaluation of obese patients.  
Study design. 
Prospective randomized single-blinded Equivalence trial  
The patient is blinded regarding the instruments used.
The endoscopist is not blinded. blinding is not feasible as the 
endoscopist would recognize the different instrument dimensions 
before the procedure. 
Primary outcome 
A composite of reaching the cecum, requiring less than 10 min for cecal 
intubation, without changing the scope type. 
Secondary outcome
cecal intubation rate (CIR)
Terminal ileum intubation rate (TIIR): The provider will attempt 
terminal ilium in every patient for at least 2 minutes and up to 5 min.
Insertion time (IT): time from insertion photo, to first cecal photo
Ancillary maneuvers use (position change, pressure application, 
increase stiffness)
Withdrawal time: time from terminal ileum ilium picture or last cecal 
picture and rectal picture – 1 min per each intervention (polypectomy, 
cauterization...etc.)
Inclusion criteria

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BMI >30
-
Screening and surveillance colonoscopy
-
Male or female
-
Age equal or more than 18 years
Exclusion criteria 
-
Colon surgery 
-
Therapeutic colonoscopy   
-
Inflammatory bowel disease  
-
Terminated procedure due to stool burden, stenosis, or obstructive 
mass.
-
Colonoscopy for anemia  
-
History of incomplete colonoscopy due to technical difficulties 
Randomization:
We will use the sealed envelope method for simple, stratified, randomization. 
-
Before the recruitment starts, we will prepare opaque sealed 
envelopes with a 1:1 ratio between the study groups, each envelope 
will have a serial number.
-
On the day of the procedure, the endoscopist will be provided with a 
few envelopes (randomly selected serial numbers), he will choose one 
randomly and open it.
-
All envelopes prepared before the recruitment process will be used 
during the study to ensure complete randomization and a 1:1 ratio 
between the study groups. 
-
The randomization will be stratified by providers performing the 
colonoscopy to ensure that each provider gets an equal assignment to 
both study groups to eliminate the bias that different providers' 
performances can introduce.
Study Operation:
1) Patient Invitation
•
The research team will review the endoscopy schedule 1-2 weeks 
before the procedure date.

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All eligible candidates who meet the inclusion criteria will be invited to 
participate in the study.
•
Candidates will be invited through A MyChart message or a mailed 
letter from the office of the provider performing the procedure.
2) Patient Consent
•
The research coordinator will call the patient within 48 hours of 
sending the invitation. During this call, the study will be explained, and 
the consent process will be discussed (phone scripts attached). 
DocuSign will be used to send the consent form virtually. The patient 
will have 1-2 days to review the consent before a follow-up call is 
made.
•
Patients who are interested in participating in the study, can elect to 
defer signing the paper consent to the day of the procedure.
Consent procedures for Patients at Coral Springs Family Health 
and Surgery Center
•
For the patients who have not signed consent via DocuSign the 
endoscopist will obtain the signature for the consent prior to the 
procedure. 
•
Then the study coordinator will open the sealed envelope and 
communicate colonoscope randomization to the provider. 
•
The endoscopist will return the signed consents to the study 
coordinator when they are in Weston. 
3) Colonoscopy
•
Endoscopists participating in the study will be informed in advance of 
the candidate's scheduled procedure date.
•
Patients will receive the usual pre-procedure care before the 
endoscopy.
•
The endoscopist will randomly select a sealed envelope to determine 
the patient group and assign the type of colonoscope.
•
As part of routine care, the endoscopist will capture photo 
documentation during the procedure, including insertion with time, 
cecum with time, terminal ileum with time, and end procedure with 
time.
•
If the endoscopist is unable to intubate the terminal ileum, a second 
cecal photo will be taken before withdrawal.
•
The endoscopist will document any additional maneuvers used, such 
as scope stiffening, changing patient position, applying pressure, or 
changing the scope.

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•
A brochure will be displayed near the computers used for procedure 
note documentation to remind providers of the required 
documentation elements after the procedure (attached).
•
A research team member will retrospectively collect the study’s 
primary and secondary outcomes from the endoscopy report and store 
them in REDCap.
•
The patient's participation in the study will conclude at the end of the 
procedure.
•
Trainees will not participate in the study procedures.
Electronic Consent Process
•
An investigator or research coordinator will contact the invited 
candidates by phone one week before the scheduled procedure. The 
study's purpose, intervention, and consent process will be discussed 
during this call, which will be documented in the patient’s chart.
•
Patients interested in participating will receive the consent form 
through DocuSign, with instructions on how to complete it online.
•
A follow-up phone call will be made 1-2 days later to answer any 
questions the patient may have.
Rationale for Electronic Consent (E-Consent)
•
Many procedures are scheduled through open access, meaning the 
patient is scheduled by a provider other than the one performing the 
procedure, often from a different department. In these cases, the 
patient may not meet the performing physician until the day of the 
procedure.
•
E-consent allows patients more time to consider participation without 
the pressure of deciding on the day of the procedure.
Sample size calculations
Assuming a 93% success rate in both arms and no true difference between 
colonoscope types, we aim to test statistical equivalence using a two-sided 
type I error of 0.05 and power of 80%. A 10% margin (±0.10) in success rate 
is considered clinically acceptable and forms the basis for the equivalence 
hypothesis:
 H0:|p1 - p2| ≥0.1 
 H1:|p1 - p2| < 0.1

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Based on these assumptions, a fixed sample size of 112 participants per 
group (total N = 224) is required. To preserve operating characteristics 
under the group sequential framework, the maximum sample size is inflated 
by an estimated factor of 1.082, yielding a maximum of 122 participants per 
group (total N = 244). The interim analysis will occur after enrollment of 122 
participants (61 per group). (Group Sequential Methods with Applications to 
Clinical Trials by Jennison and Turnbull (pages 149–150) [2]. 
Study Variables 
Date of birth, gender, race, BMI, previous pelvic\abdominal surgery, 
diverticulosis, colon prep (adequate- inadequate), type of colonoscopy, 
insertion time, cecum and terminal ileum intubation success, and procedure 
time. Please refer to the data collection sheet for details of the variables 
above.
 
Data Analysis
All statistical analyses will be conducted by a statistician from the Cleveland 
Clinic’s Quantitative Health Sciences (CCF QHS) team, following the 
intention-to-treat (ITT) principle. This means that all randomized patients 
who receive one of the study interventions will be included in the primary 
analysis.
Baseline characteristics will be assessed for balance using standardized 
mean differences (SMDs), with a value less than 0.10 (absolute) indicating 
acceptable balance.
Missing data in baseline variables are expected to be minimal. If more than 
5% of data are missing for any key variable, multiple imputation methods 
will be employed. 
The primary outcome—successful completion of the colonoscopy (Yes/No)—
will be analyzed as a binary endpoint. The effect of colonoscope type (adult 
vs. pediatric) will be evaluated using the Two One-Sided Tests (TOST) 
procedure, with a pre-specified equivalence margin of ±10%. The absolute 
risk difference of 10% will also be translated into corresponding thresholds 
for odds ratios (OR = 2.72 or OR = 0.36) and relative risks (RR = 1.12 or RR 
= 0.893). Both unadjusted and adjusted logistic regression models, 
incorporating pre-specified covariates, will be used to estimate treatment 

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effects. Results will be presented as risk differences, relative risks, and odds 
ratios, with 95% confidence intervals derived via the g-computation method. 
Equivalence will be declared if the full confidence interval lies entirely within 
the specified equivalence range on each metric.
A per-protocol analysis will be conducted as a sensitivity analysis if there is 
substantial non-compliance. Additional sensitivity analyses will be considered 
to address missing data in outcome variables.
Secondary outcomes including cecal intubation rate (CIR), terminal ileum 
intubation rate (TIIR), insertion time (IT), use of ancillary maneuvers, 
withdrawal time, are considered independent of the primary outcome. 
Categorical secondary outcomes will be compared using chi-squared or 
Fisher’s exact tests, while continuous variables will be analyzed using two-
sample t-tests or Wilcoxon rank-sum tests as appropriate. Regression models 
adjusting for pre-specified covariates will also be considered.
Repeatedly measured outcomes will be analyzed using mixed-effects 
models, with study group and time point included as fixed effects, and 
subject ID as a random effect to account for within-subject correlation. This 
approach is robust to data that are missing at random (MAR) or missing 
completely at random (MCAR).
Data Security 
Data, including patient information and consent, will be stored electronically 
in the Redcap system\DocuSign which is password-protected and on the 
secure Cleveland Clinic network. If physical paper sheets were used, the 
physical paper sheets' information would be transferred to Redcap and 
shredded on the day of data gathering.
Interim analysis
A group sequential design with a single interim analysis at 50% enrollment is 
proposed. This design allows early trial termination for either efficacy 
(equivalence) or futility (non-equivalence), while preserving the overall type I 
error (α = 0.05) and power (1 − β = 0.80).
The design employs Hwang-Shih-DeCani gamma error spending functions 
[1]:

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Type I error: γ = –4 (O’Brien-Fleming–like)
•
Type II error: γ = 1 (Pocock-like)
Analysis 
Stage
Type I Error Spending 
(Cumulative)
Type II Error Spending 
(Cumulvative)
Interim 
(50%)
0.00596
0.124
Final 
(100%)
0.05
0.2
A non-binding futility boundary is used. Z-stopping-boundaries are shown 
below.
Analysis Stage Equivalence
upper
Equivalence
lower
Non-equivalence
upper
Non-equivalence
lower
Interim (50%)
2.749966
-2.749966
1.152821
-1.152821
Final (100%)
1.959964
-1.959964
1.959964
-1.959964
Possible Harm to Subjects 
Both study arms are considered standard treatment, and no anticipated 
harm is related to the study.