A Prospective, Multi-Center Evaluation of the ECHELON CIRCULAR Powered Stapler in Left-Sided Colorectal Anastomoses: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Prospective, Multi-Center Evaluation of the ECHELON CIRCULAR Powered Stapler in Left-Sided Colorectal Anastomoses (NCT03326895), a na na study. The primary outcome is Percentage of Participants With Stapler Performance Issues.

2. Clinical Question

3. Trial Design

This was a prospective, multicenter evaluation of the ECHELON CIRCULAR Powered Stapler in left-sided colorectal anastomoses. The registry describes the study as single-group, with the powered circular stapler used to complete the colon anastomosis. It is a post-market evaluation focused on intraoperative performance, rather than a randomized comparison of treatment strategies. Allocation is listed as not applicable, and masking is listed as none.

The record reports enrollment of 168. The study start date is 2017-11-20, primary completion is dated 2019-12-06, and the study status is completed. Ethicon Endo-Surgery is identified as the sponsor. These design and status details describe the study structure; they do not establish how many participants contributed data to the primary endpoint.

The primary outcome was the percentage of participants with stapler performance issues during surgery. The registry also lists the SURG-TLX Questionnaire as a secondary outcome and reports two outcome measures in total. It reports no analyses. The endpoint result, confidence interval, analysis population, and handling of missing outcome data are not reported in the registry record.

Because there is no comparator group, the study can describe performance observations in the enrolled group but cannot estimate a comparative effect against another device or procedure. The record does not report a protocol-level sample-size justification or a statistical analysis plan. Planning assumptions associated with sample-size illustrations should not be read as evidence that the trial itself was designed or analyzed as a two-arm comparison.

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

Analysis population for the primary outcome, as defined in the registry: Number of subjects with at least performance issue.

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 Percentage of Participants With Stapler Performance Issues, measured over Intraoperative.

The primary endpoint is the percentage of participants with at least one stapler performance issue during the intraoperative period. The registry defines an issue as failure of the ECHELON CIRCULAR Powered Stapler to perform according to its instructions for use. The examples span problems with placement or removal, device firing, staple formation, staple-line integrity, tissue damage, leak testing, and detached components. The definition also includes other device failures, so it is broader than any single technical complication.

A participant-based binary endpoint reduces each participant’s experience to whether at least one qualifying issue occurred. This can provide a clear summary of how often the prespecified type of problem was observed in the study group. It does not describe the number of separate issues per participant, their duration, severity, or clinical consequences unless those details are reported separately.

The registry identifies the endpoint unit as percentage of subjects and specifies a 95% confidence interval as the dispersion measure. A confidence interval communicates uncertainty around an estimated percentage; narrower intervals generally indicate greater precision, while wider intervals indicate less precision. Neither the endpoint estimate nor its interval is reported in the registry record, so the observed frequency and precision cannot be assessed from this record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is binary at the participant level: each participant either had at least one qualifying performance issue during the intraoperative period or did not. A percentage summarizes the proportion of assessed participants meeting that definition. For this type of endpoint, the denominator matters: it should be clear which participants were included in the assessment, and whether all enrolled participants had usable endpoint information. The registry record does not report the endpoint result, denominator used, or analysis population.

What a confidence interval conveys

The registry specifies a 95% confidence interval for the primary percentage. In general, a confidence interval describes the uncertainty associated with an estimate, reflecting that an observed study group is one realization rather than a complete accounting of every possible experience in the broader population of interest. The interval is not a guarantee that the true value lies within its limits, and it does not remove design limitations such as the lack of a comparator. Since no interval limits are reported, the precision of the primary estimate cannot be evaluated.

Why the endpoint definition matters

The endpoint definition groups multiple kinds of performance problem together. This creates a single summary measure, but different qualifying issues may vary in nature and consequence. The broad definition includes examples such as difficulty placing or removing the stapler, misfire or incomplete firing, staple-line defects, incomplete or thin donuts, tissue damage, a positive intraoperative leak test, detached components, and unformed staples. It also includes other device failure. General interpretation of a composite or broad endpoint depends on consistent application of its definition and on knowing which component events occurred. Details about assessment procedures and component-level results are not reported in the registry record.

What a single-group design can estimate

In general, a single-group study can estimate the frequency of an outcome observed in the study group, subject to the quality and completeness of outcome measurement. It cannot isolate a comparative effect because there is no concurrent control group to distinguish the device experience from other influences. This evaluation is listed as single-group, with allocation not applicable and masking none. No randomized or like-for-like comparison is described. Accordingly, any descriptive frequency would pertain to the observed group and study context, not a comparison with an alternative.

Planning calculations and observed results

The sample-size planning assumptions describe an illustration based on a stated fraction of an observed effect, a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. These are planning assumptions, not a reported analysis of the single-group study. The assumptions do not establish that a two-arm design was used, nor do they provide the missing primary endpoint result. Sample-size illustrations are planning quantities, not observed power. They should not be read as evidence that the study had a particular ability to detect an effect after data collection.

For planning calculations in general, the assumed effect and design determine the estimated sample size needed under a specified statistical model. If the assumed effect changes, the planning estimate changes as well. A planning illustration based on a fraction of an observed effect is therefore conditional on that chosen effect scenario; it does not demonstrate that the effect is real or that the trial’s design was based on it. The record does not report its own sample-size justification.

Over-dispersion and event summaries

For a binary endpoint, standard methods often describe uncertainty around a participant-level proportion. General statistical models can be inadequate when the observed variability exceeds what the model assumes; this is called over-dispersion. In that setting, uncertainty estimates may be too narrow if extra variability is ignored. Whether over-dispersion is relevant depends on the analysis model and data structure. The registry record does not report a model, an over-dispersion assessment, or an analysis of the primary endpoint, so no claim can be made about whether these issues were considered.

Finally, statistical interpretation depends on reporting more than an endpoint definition. The estimate, uncertainty interval, denominator, missing-data approach, and analysis population are needed to assess what the result represents. Those primary-analysis details are not reported in the registry record. The posted information therefore permits explanation of the intended endpoint and general statistical principles, but not a reconstruction or verification of the primary analysis.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("ECHELON CIRCULAR Powered Stapler")
n      <- c(168)
events <- c(20)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  ECHELON CIRCULAR Powered Stapler  168  20  11.9  7.4  17.8  7.8  17.7  7.9  17.7

11. Multiplicity, Missing Data and Analysis Populations

The registry lists the SURG-TLX Questionnaire as a secondary outcome and reports two outcome measures in total. It reports no analyses. A multiplicity plan describing how statistical testing across outcomes was handled is not reported in the registry record. Without that information, it is not possible to determine whether any planned tests were adjusted, prioritized, or treated as descriptive. The record does not report endpoint-specific hypothesis tests or p-values.

Missing-data handling is also not reported. The record does not specify how participants with unavailable primary endpoint information were treated, whether any values were imputed, or whether sensitivity analyses were conducted. These details matter because the denominator used for a participant-level percentage affects what that estimate describes. Enrollment of 168 does not, by itself, establish that all 168 contributed to the primary endpoint analysis.

The analysis population is not reported in the registry record. No description is given of whether the primary endpoint was assessed in all enrolled participants or in a defined subset. The record also does not state how performance issues were reviewed or classified, or how disagreements or uncertain cases were handled. Those omissions limit assessment of the endpoint’s completeness and consistency.

Because no primary analysis is reported, it is not possible to assess the influence of missing data, multiplicity, or analysis-population choices on a numerical conclusion. These are reporting gaps, not evidence that a particular method was or was not used.

12. 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 1.2% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: gastrointestinal stoma complication (1.8%), anastomotic leak (1.2%), pelvic abscess (1.2%), anastomotic stenosis (0.6%), incision site pain (0.6%).

The adverse-event information lists 168 participants at risk in the ECHELON CIRCULAR Powered Stapler group. It reports 13 participants affected by serious adverse events, 32 affected by other adverse events, and zero deaths. These are descriptive safety figures. They do not establish how events were related to the device, the procedure, or other causes; causal attribution is not reported in the registry record.

The serious adverse-event terms listed include Gastrointestinal Stoma Complication at 1.8%, Anastomotic Leak at 1.2%, Pelvic Abscess at 1.2%, Anastomotic Stenosis at 0.6%, Incision Site Pain at 0.6%, and Post Procedural Hemorrhage at 0.6%. These percentages should be read as registry-listed term frequencies, not as comparative risks. No control group is described, and the record does not provide a comparative estimate or confidence interval for these terms.

The counts of participants affected and the listed term percentages should not be added or treated as mutually exclusive categories. The record does not state whether a participant could contribute more than one event or appear under more than one term. These safety data are separate from the primary endpoint of stapler performance issues and do not fill in its missing result.

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

The study was designed to evaluate intraoperative performance of a powered circular stapler used in left-sided colon resection. Its primary endpoint focused on whether a participant experienced at least one performance issue as defined by the registry. This is a specific descriptive question about the enrolled study group, not a randomized comparison of devices or procedures.

The registry record does not report the primary endpoint percentage or its 95% confidence interval. As a result, it does not show how often a qualifying performance issue was observed or how precisely that frequency was estimated. The missing result must not be interpreted as a zero event rate or as evidence that performance issues did not occur.

The single-group design also means that any endpoint frequency, if reported, would not show how the stapler compares with an alternative. Differences between groups cannot be estimated where no comparison group is described. Factors beyond the device itself could also contribute to outcomes in a prospective clinical setting; the registry information does not separate such influences.

The adverse-event figures provide a separate descriptive view: 13 participants had serious adverse events, 32 had other adverse events, and zero deaths were reported among 168 at risk. The listed serious-event terms give additional safety context, but neither those figures nor the completion status answer the primary performance question. The record does not report event attribution or a comparison that would support causal interpretation.

Overall, the information establishes the study’s purpose, design, endpoint definition, enrollment, and selected safety findings. It does not provide enough primary outcome information to estimate performance-issue frequency, assess the precision of that estimate, or make a comparative claim. Conclusions about those questions are not reported in the registry record.

14. Why This Trial Matters Statistically

Registry records are useful for distinguishing the question a study set out to address from what its posted results actually report. In this evaluation, the primary question is stated clearly: the percentage of participants with at least one intraoperative stapler performance issue. The record also specifies a confidence interval as the intended measure of uncertainty. Yet the estimate and interval are not reported. That gap matters because an endpoint definition alone cannot reveal how often the outcome occurred or how precisely it was measured.

The single-group structure is another important statistical feature. A descriptive evaluation can characterize observations in a group using the device, but it does not provide the counterfactual comparison needed to estimate what would have happened with another device or approach. Readers should therefore separate questions about observed performance from questions about comparative effects.

The broad endpoint definition also makes transparent reporting important. A summary percentage could combine different types of issue, from problems with firing to tissue damage or leak-test findings. Without the estimate and component-level detail, the record cannot show which kinds of issue contributed to the endpoint or whether one type predominated.

Finally, the adverse-event figures illustrate why distinct outcomes should remain distinct. Serious and other adverse-event counts describe safety reporting, while the primary endpoint concerns device performance issues. Neither should be used as a substitute for the other. A careful statistical reading can state what the registry reports, identify what it leaves unreported, and avoid turning descriptive information into comparative or causal conclusions.

15. 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 main limitation for interpretation is that the primary endpoint result is not reported in the registry record. Although the endpoint definition and intended confidence-interval measure are stated, no percentage, interval limits, or analysis details are given. The primary question therefore remains unanswered in the posted results.

The study is single-group and has no separate comparator. This prevents a like-for-like statistical comparison with another device or procedure. The record lists masking as none and allocation as not applicable; it does not describe randomization or a blinded outcome assessment. Further details about endpoint ascertainment, event adjudication, or consistency of assessment are not reported.

Enrollment is reported as 168, but the number included in the primary endpoint analysis is not reported. The analysis population, missing-data handling, and denominator for the endpoint are likewise not reported. The registry lists a secondary outcome, the SURG-TLX Questionnaire, but does not report its result or analysis. It also reports no analyses, leaving the statistical methods used for the outcome unavailable.

The performance endpoint combines a range of possible issues, and the record does not report component-level results. The safety information is descriptive and does not establish event attribution or comparative risk. Finally, the sample-size assumptions describe a planning illustration using equal allocation between two arms and a normal approximation; they are not a reported justification for this single-group study. These limitations constrain conclusions about frequency, precision, causation, and comparison.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Prospective, Multi-Center Evaluation of the ECHELON CIRCULAR Powered Stapler in Left-Sided Colorectal Anastomoses — NCT03326895.
• Registry record last updated 2021-01-11; status last verified 2021-01.
• Results first posted 2021-01-11.
• 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.

19. Record Summary

NCT03326895 is a completed, prospective, multicenter, single-group post-market evaluation of the ECHELON CIRCULAR Powered Stapler in left-sided colorectal anastomoses. The registry reports enrollment of 168, with a study start date of 2017-11-20 and primary completion date of 2019-12-06. Ethicon Endo-Surgery is listed as sponsor.

The primary endpoint was the percentage of participants with at least one intraoperative stapler performance issue, with a 95% confidence interval specified. The registry record does not report the endpoint estimate, interval, or analysis. It lists the SURG-TLX Questionnaire as a secondary outcome and reports no analyses.

Safety information lists 13 participants with serious adverse events, 32 with other adverse events, and zero deaths among 168 at risk. The study has no comparator group, so it does not provide a comparative estimate against another device or procedure.