Use of a Distal Colonoscope Attachment to Increase Detection of Sessile Serrated Adenomas: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Use of a Distal Colonoscope Attachment to Increase Detection of Sessile Serrated Adenomas (NCT03560037), a randomized na study. The primary outcome is Sessile Serrated Adenomas.

2. Clinical Question

The study addresses a detection question: whether adding a distal attachment to the colonoscope changes how often a colonoscopy identifies at least one sessile serrated adenoma. The endpoint is recorded as a count of colonoscopies meeting that condition, rather than as the number of adenomas found in each participant. That distinction matters because a colonoscopy with several findings still contributes to the primary endpoint as a colonoscopy with at least one finding.

The trial randomized participants to the two procedures. The primary outcome population is described as participants with complete colonoscopy. The registry reports 42.0 colonoscopies with at least one sessile serrated adenoma in the Standard Colonoscopy arm, with 215.0 in the arm-level result, and 59.0 in the Endocuff Vision Assisted Colonoscopy arm, with 210.0 in its arm-level result. These counts alone do not express the uncertainty in an arm-to-arm difference. The registry record does not report an estimable comparison, confidence interval, or p-value for this primary outcome, so the raw counts should not be treated as a complete statistical answer to the clinical question.

3. Trial Design

This was a randomized, parallel-group study with single masking. Participants were assigned to standard colonoscopy without a distal attachment or colonoscopy with the Endocuff Vision distal attachment. The registry lists the study as completed and records enrollment of 427. The arm-level primary outcome results list 215.0 for Standard Colonoscopy and 210.0 for Endocuff Vision Assisted Colonoscopy. The registry record does not explain the relationship between the total enrollment and those outcome arm counts.

The sponsor is the University of California, Davis. The study start date is 2019-05-01, and the primary completion date is 2023-12-05. Phase is listed as NA. The registry describes the main assessment as occurring when pathology results became available 2 weeks after the procedure. It also says that data would be collected through study completion and analyzed and reported up to 6 months after study completion. The record does not provide a separate study completion date in the registry record for this description.

Random allocation is relevant because it is intended to make treatment groups comparable on average, including for characteristics that are not measured. It does not guarantee that groups are identical, and it cannot resolve limitations caused by missing outcome data or incomplete reporting. The registry identifies the design as single-masked but does not say who was masked. It does not report the allocation ratio or procedural details beyond the distinction between standard colonoscopy and use of the distal attachment.

The registry lists adenoma detection, proximal colon adenomas, adenomas per colonoscopy, sessile serrated adenomas per colonoscopy, adenomas per positive colonoscopy, sessile serrated adenomas per positive colonoscopy, colonoscope withdrawal time, and differences in quality of bowel preparation as secondary outcomes. Nine outcome measures are listed, while eight secondary outcomes are posted. The registry record does not report the protocol’s planned sample-size justification or the statistical analysis plan.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Participants with complete colonoscopy

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Sessile Serrated Adenomas, measured over Time point of assessment will be when pathology results are made available 2 weeks after procedure. Data will be collected through study completion, analyzed and reported up to 6 months after study completion..

The primary endpoint is the number of colonoscopies with at least one sessile serrated adenoma among participants with complete colonoscopy. It captures whether a procedure identified any lesion of the specified type. It does not count how many such adenomas were found once a colonoscopy has at least one, and it is distinct from an average count of adenomas per participant.

This kind of endpoint is useful for a detection question because it records the frequency of procedures with at least one qualifying finding. A comparison between randomized arms could describe whether that frequency differs between the procedures. Interpreting the comparison would normally require both the arm-level data and an estimate of the between-arm effect with its uncertainty, along with an account of which participants contributed data.

The registry reports arm-level counts of 42.0 for Standard Colonoscopy and 59.0 for Endocuff Vision Assisted Colonoscopy, with arm-level results of 215.0 and 210.0, respectively. However, it does not report an estimable two-arm comparison for this count outcome. No primary endpoint confidence interval or p-value is reported in the registry record. Consequently, the posted counts describe the observed arms but do not establish the precision or statistical significance of a difference.

The endpoint is assessed after pathology results are available, with the registry describing that timing as 2 weeks after the procedure. Pathology confirmation is part of how the outcome is defined in the record; further details about assessment procedures or adjudication are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical results require a distinction between the primary count endpoint and the continuous secondary outcomes. The primary endpoint is the number of colonoscopies with at least one sessile serrated adenoma. The registry provides arm-level counts, but its record indicates that values are missing or not estimable for a two-arm comparison of this count outcome. The results therefore do not include a primary effect estimate with uncertainty. The secondary results include means, standard deviations, and recalculated unadjusted mean differences for three outcomes.

What does a mean difference describe?

For a continuous outcome, a mean difference is the difference between the average value in one arm and the average value in the other. A positive value in these recalculations means the posted average is higher in the Endocuff Vision Assisted Colonoscopy arm than in the Standard Colonoscopy arm. It is an estimate of the difference in averages, not a count of additional participants and not a causal guarantee for an individual. The arm means and participant counts are the inputs to the posted recalculations. The registry does not list sponsor-reported analyses for these three outcomes.

A confidence interval expresses uncertainty around an estimate under the assumptions of the method used. It gives a range of values that are compatible with the data and method at the stated confidence level. It is not a guarantee that the true value lies in that particular realized interval, nor does it represent the range of individual participant outcomes. For all three posted secondary mean differences, the confidence interval includes zero. Zero represents no difference in group means. This means that the recalculated intervals do not rule out a null mean difference, while also allowing for nonzero differences.

How should the p-values be read?

A p-value measures how unusual data at least as discrepant as those observed would be under a specified null model and the test’s assumptions. It is not the probability that the null hypothesis is true, and it does not measure clinical importance. The posted secondary p-values are unadjusted: 0.056 for adenomas per colonoscopy, 0.219 for sessile serrated adenomas per colonoscopy, and 0.305 for adenomas per positive colonoscopy. Their interpretation should remain tied to the corresponding mean comparisons. The registry record does not report that these recalculated tests formed the prespecified analysis plan or that they were adjusted for examining multiple outcomes.

The calculations are described as simple, unadjusted recalculations from posted summary statistics. They should not be mistaken for a complete trial analysis. A trial’s planned analysis may account for design features, covariates, missing observations, or other considerations. Whether such methods were planned or used is not reported in the registry record. The sponsor’s own analysis takes precedence if there is a discrepancy; no discrepancy is flagged in the available record, and no sponsor-reported analyses are posted for these secondary outcomes.

Why do the standard deviations matter?

A standard deviation describes the spread of participant-level observations around an arm mean. It is not the same as a standard error, which describes the uncertainty of an estimated mean. The secondary outcomes have standard deviations that are sizeable relative to their means, indicating variation among observations. In general, when a count outcome varies more than a simple model assumes, over-dispersion can make methods that assume a simpler distribution give overly narrow uncertainty estimates. A count model that allows extra variation may be appropriate in some settings, but the registry record does not specify a model for the primary count outcome or provide enough information to judge model fit.

The secondary comparisons use a mean-based summary. This is straightforward to describe, but a mean alone does not show the shape of a count distribution. Count outcomes can include many low values and a smaller number of larger values, so the mean and standard deviation may not capture every feature relevant to analysis. Whether the study planned another model or a transformation is not reported in the registry record. The recalculated results should accordingly be read as summaries based on the posted means and standard deviations, not as a substitute for a protocol-defined model.

What do the planning illustrations mean?

The sample-size illustrations are based on fractions of the observed secondary mean differences and are not the trial’s own design justification. Their assumptions are a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. For each stated fraction of the observed effect, the illustrations give participants per arm for 80% power and participants per arm for 90% power. They are planning scenarios, not observed power and not evidence that the completed trial did or did not have sufficient power for its primary endpoint.

Planning from an observed effect can be unstable because that estimate is itself uncertain. If a future study aims to detect a smaller effect than the observed estimate, the required sample size in such an illustration grows. These calculations also do not address the primary endpoint’s unestimable comparison, since they are attached to the continuous secondary mean outcomes. The actual sample-size rationale, target effect, allowance for incomplete colonoscopy or missing pathology, and planned power for the primary endpoint are not reported in the registry record.

In general, randomization supports comparisons between assigned groups, but interpretation still depends on the analysis population and handling of missing outcomes. The primary endpoint is explicitly defined for participants with complete colonoscopy, while the registry does not report how incomplete procedures were handled in the analysis. It also does not report whether analyses followed assigned groups or another population definition. Those details matter because exclusions after randomization can affect comparability.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary endpoint and multiple secondary outcomes, but does not report how the analysis plan handled multiple statistical tests. Multiplicity matters because testing many outcomes can increase the chance that at least one result appears unusual even when there is no underlying effect. An adjustment or a prespecified hierarchy can help control that interpretive problem. No such approach is reported in the registry record. The secondary p-values are unadjusted recalculations, so they should not be interpreted as though they account for all outcome comparisons.

Information about missing data is also limited. The primary outcome population is described as participants with complete colonoscopy, but the registry does not say how many randomized participants had incomplete procedures, whether outcome data were missing, or how missingness was handled. It does not report an imputation method, a sensitivity analysis, or a comparison of participants with and without complete outcome data. Those omissions limit assessment of how representative the analyzed observations are of all randomized participants.

The record does not state whether the primary or secondary analyses followed intention-to-treat principles, used a per-protocol population, or applied another analysis-population definition. It does not describe exclusions after randomization or how deviations from assigned procedures were treated. These details are important because excluding participants or analyzing them according to treatment received can weaken the protection randomization provides.

The primary count comparison is not estimable in the posted results, and no sponsor-reported analyses are listed for the secondary continuous outcomes. The registry record does not provide the prespecified statistical analysis plan, adjustment for any design factors, or sensitivity analyses. These points should be treated as reporting gaps, not evidence that a method was or was not used. The available results support descriptive summaries and limited unadjusted recalculations, rather than a complete reconstruction of the trial’s intended confirmatory analysis.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 1% reporting threshold.

The registry reports zero serious adverse events, zero other adverse events, and zero deaths in each arm. The serious-event risk groups are 216 for Standard Colonoscopy and 211 for Endocuff Vision Assisted Colonoscopy; the other-adverse-event risk groups have the same arm counts. These are the safety figures recorded for the groups at risk in the adverse-event results.

Zero recorded events in these groups means that the registry lists no events in those categories during the reporting period. It does not establish that the procedures have no risk, nor does it show that two procedures have identical safety profiles. Rare events can be absent in a study even when the true event risk is not zero, and the interpretation depends on follow-up duration, event definitions, and completeness of reporting. Those details are not reported in the registry record.

The safety group counts differ from the arm-level counts listed for the primary outcome. The registry does not explain the relationship between those populations or provide further detail about adverse-event ascertainment. No serious adverse-event terms are listed. The reported figures should therefore be read narrowly as the adverse-event counts in this registry record, not as a comprehensive assessment of all possible harms.

12. What the Result Does, and Does Not, Mean

The primary endpoint was intended to compare how often colonoscopies identified at least one sessile serrated adenoma with standard colonoscopy versus the Endocuff Vision attachment. The registry records 42.0 such colonoscopies in the Standard Colonoscopy arm and 59.0 in the Endocuff Vision Assisted Colonoscopy arm. Since the arm-level result counts are not identical, the raw counts alone do not provide a fair or precise estimate of the difference. The registry does not report the comparison needed to quantify that difference and its uncertainty.

The secondary recalculations show higher arm means for the three posted continuous outcomes in the Endocuff Vision group, but their confidence intervals include zero. This is compatible with no mean difference and with some nonzero differences. It does not demonstrate equivalence, because equivalence requires a defined margin and an analysis designed to evaluate that question. Neither an equivalence margin nor an equivalence analysis is reported in the registry record.

Nor do the results establish that the attachment caused a change in detection. Randomization is an important design feature for causal comparison, but the primary contrast is not posted, the analysis population and missing-data handling are not described, and the secondary results are unadjusted recalculations. These limitations prevent a complete assessment of the strength and robustness of the evidence from the registry record alone.

The reported findings also do not establish what would happen in every screening setting or for every participant. The record describes a particular randomized study and provides only the outcomes listed. It does not report enough detail about participant characteristics, procedural conduct, or assessment processes to evaluate how closely the study population and procedures match other settings. The correct statistical conclusion is bounded: arm-level counts and secondary summaries are posted, but the primary comparative estimate and important analysis details are not reported in the registry record.

13. Why This Trial Matters Statistically

This trial is statistically notable because its primary endpoint is a count of procedures with at least one finding, while its posted recalculated secondary results focus on mean counts. Those are different estimands and answer related, but not identical, questions. Keeping the endpoint definition in view prevents an average number of adenomas from being mistaken for the probability or frequency of a colonoscopy detecting any qualifying lesion.

The record also illustrates why arm-level results do not automatically constitute a treatment comparison. The primary arm counts are available, but an effect estimate and its uncertainty are not. Without those, readers cannot assess the precision of the primary contrast using the registry results. The continuous secondary outcomes have recalculated comparisons, but these remain exploratory in the absence of posted sponsor analyses and a reported multiplicity plan.

Finally, planning illustrations based on observed secondary effects are not a substitute for a trial’s original design rationale. They can demonstrate how assumptions about the target effect and desired power influence planning, but they do not reveal the actual target effect or power assumptions used when the study was designed. The registry does not report those design details. This distinction is important when interpreting a completed study: sample-size scenarios based on observed outcomes are planning aids, not evidence about the adequacy of the original design.

Overall, the record offers useful descriptive information and a clear randomized intervention contrast, but its inferential value is constrained by the missing primary comparison and limited analysis reporting. Recognizing that boundary is part of sound statistical interpretation.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The most important trial-specific limitation in the registry results is that the primary count endpoint has no estimable two-arm comparison. The arm-level counts are reported, but there is no primary effect estimate, confidence interval, or p-value. Thus, the central question cannot be evaluated with a quantified comparative result from the registry record.

The result population is described as participants with complete colonoscopy, yet the record does not report the number with incomplete colonoscopy or how these participants were treated in analysis. It also does not explain the difference between the arm counts attached to the primary results and those listed for safety. Without participant flow and analysis-population details, the extent to which the posted outcome groups represent all randomized participants is unclear.

For the secondary outcomes, the available comparisons are unadjusted recalculations based on summary statistics. No sponsor-reported analyses are listed, and the record does not state whether the outcomes, models, or comparisons were prespecified. The multiple listed outcomes raise the possibility of selective emphasis, but the registry does not provide enough information to assess that directly. No multiplicity adjustment or sensitivity analysis is reported.

Other details that would support interpretation are absent: the masking role, allocation ratio, sample-size justification, protocol-defined analysis methods, missing-data procedures, and endpoint assessment or adjudication procedures. Their absence from the registry record does not prove that these items were absent from the study conduct; it means they cannot be assessed from the posted record. The adverse-event reporting is also limited to the recorded counts and does not provide event definitions or follow-up detail.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Use of a Distal Colonoscope Attachment to Increase Detection of Sessile Serrated Adenomas — NCT03560037.
• Registry record last updated 2025-09-22; status last verified 2025-09.
• Results first posted 2025-09-22.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

NCT03560037 is a completed, randomized, parallel-group, single-masked study sponsored by the University of California, Davis. It compares standard colonoscopy without a distal attachment with colonoscopy using Endocuff Vision. Enrollment is listed as 427; the study start date is 2019-05-01 and the primary completion date is 2023-12-05.

The primary outcome is the number of colonoscopies with at least one sessile serrated adenoma among participants with complete colonoscopy. Arm-level counts are posted, but an estimable primary comparison is not. Three continuous secondary outcomes have unadjusted recalculations whose confidence intervals include zero. The registry record does not report sponsor analyses, the statistical analysis plan, or key details about missing data and multiplicity. Safety results list zero serious adverse events, zero other adverse events, and zero deaths in both arms.