Zip-Stitch™ for Vaginal Cuff Closure in Laparoscopic Hysterectomy - Safety & Efficacy Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Zip-Stitch™ for Vaginal Cuff Closure in Laparoscopic Hysterectomy - Safety & Efficacy Study (NCT04081727), a randomized na study. The primary outcome is Primary Efficacy Endpoint - Number of Participants With Implant Passing.

2. Clinical Question

3. Trial Design

The registry describes a randomized, triple-masked, parallel-group study of Zip-stitch for vaginal cuff closure in laparoscopic hysterectomy. Its status is terminated. The study start date is 2019-11-06, and the primary completion date is 2020-08-31. Enrollment is listed as 2. The record identifies ZSX Medical LLC as the sponsor and lists the phase as NA.

The two groups are the test article, Zip-stitch clips, and a reference suture group. The reference is described as V-Loc barbed suture in the study summary and arm description. The posted outcome and safety records instead label the reference as VICRYL or Vicryl Suture. This naming discrepancy makes the comparator description unclear in the record and should be kept in mind when interpreting the posted results. The arm description says the reference group was not intended to be comparative against the test article, but was included for reference and safety.

Randomization and triple masking are features recorded for the study design, but the registry does not describe the allocation procedure, who was masked, or how masking was maintained. Those details are not reported in the registry record. The posted primary outcome population is described as analyzed “as-treated,” which is distinct from an intention-to-treat population. Further detail on the analysis population is not reported.

The trial record lists 9 outcome measures, including 7 posted secondary outcomes. These cover closure success, healing, implant passing, safety-related implant-passing events, adverse events, dyspareunia, and pain. The record lists 0 analyses. It does not report a sample-size justification, detailed statistical analysis plan, or reason for termination. The enrollment of 2 and the termination status constrain how much can be learned from the posted results.

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: Data analyzed "as-treated."

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.

Population: Study was stopped after two subjects enrolled

6. Primary Endpoint

The registry lists the primary outcome as Primary Efficacy Endpoint - Number of Participants With Implant Passing, measured over Six-weeks post-operative.

The primary efficacy endpoint is the number of participants with implant passing after laparoscopic vaginal cuff closure. The registry specifies a six-weeks post-operative timeframe and describes the measure as the frequency of implant passing within six weeks. It is expressed as a participant count, not as a time-to-event measure or a measurement of the amount of material passed. The endpoint is recorded for participants analyzed “as-treated.”

Implant passing was selected as the primary measure because the stated primary objective was to evaluate safety and efficacy of the Zip-stitch Vaginal Cuff Closure System, primarily by measuring this event after system use. As a general statistical concept, a clearly defined primary endpoint focuses interpretation on a prespecified outcome rather than allowing attention to shift among many outcomes after results are known. The registry identifies the endpoint and timeframe, but a fuller operational definition of what qualified as implant passing is not reported in the registry record.

The posted primary result is 0.0 participants in the Zip-stitch group and 1.0 participant in the reference group. Each group is listed with 1.0 participant. These are observed counts from a very small enrolled sample, not stable estimates of the event frequency in a wider population. The registry does not post a confidence interval, a comparative effect estimate, or an inferential test for this endpoint. The meaning of the difference in the observed counts is consequently limited: the record documents what was counted among the enrolled participants, but does not quantify uncertainty or establish a reliable group contrast.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods help distinguish an observed result from an estimate of what might occur in a larger population. In this study, the primary outcome is a participant count: whether implant passing was recorded during the six-weeks post-operative timeframe. The registry posts a count of 0.0 for Zip-stitch and 1.0 for the reference group, with 1.0 participant in each. Since the outcome is a count of participants with an event, the data are binary at the participant level: each participant either has the event recorded or does not. The endpoint is not a count of separate implant-passing episodes.

What does a confidence interval add?

As a general statistical concept, a confidence interval expresses the uncertainty around an estimate by giving a range of values compatible with the observed data under a specified method. It helps readers see how much precision the data provide, rather than focusing only on a single estimate. A narrow interval generally indicates more precision than a wide interval. With very few observations, estimates for event frequencies or group differences are inherently uncertain. The registry does not post a confidence interval for the primary endpoint, so the precision of a comparative estimate cannot be read directly from the record.

A confidence interval would not make a small dataset larger or eliminate limitations in the design. It would quantify sampling uncertainty under its assumptions. It also would not resolve ambiguity in the comparator’s naming or clarify what qualified as implant passing. Those are questions of record quality and outcome definition, rather than uncertainty that an interval can repair.

Why does the sample size matter?

As a general concept, the amount of information in an analysis depends on both the number of observations and how frequently the outcome occurs. When only a few participants are observed, a single outcome can substantially change the apparent event frequency. This is why the posted counts should be read as descriptions of the enrolled participants, not as precise rates for a broader clinical population. The registry enrollment is 2, with one participant listed in each endpoint group.

Planning sample sizes are different from observed results. A sample-size calculation uses assumptions about the effect to detect, the significance level, allocation, and a statistical method to illustrate how many participants might be needed under those assumptions. It is a planning exercise, not a result from enrolled participants and not a measure of observed power. The registry record does not report its own sample-size justification. No planning illustration should be mistaken for evidence that the study was adequately sized or that an observed effect is established.

What does randomization contribute?

As a general concept, random allocation is intended to balance measured and unmeasured participant characteristics across groups over repeated use of the same design. It does not guarantee balance in a particular small trial. The record identifies the allocation as randomized and the design as parallel, but does not give the allocation sequence method or describe safeguards around assignment. With enrollment of 2, the fact of randomization should not be taken to imply that the groups are meaningfully comparable on all relevant characteristics.

The record also calls the trial triple-masked, but it does not say which people were masked or how masking was preserved. Masking can reduce the influence of expectations on care, reporting, or assessment, depending on who is masked and how the outcome is ascertained. Without those details, the label cannot be used to evaluate the practical protection against bias in this particular study.

How should the as-treated analysis be understood?

The primary outcome description says the data were analyzed “as-treated.” As a general concept, an as-treated analysis groups participants according to the treatment they actually received, whereas an intention-to-treat analysis generally retains participants in their assigned groups. The choice can affect interpretation, particularly if participants do not receive their assigned intervention or switch groups. The registry does not report whether any such circumstances occurred, nor does it describe the full analysis population beyond the as-treated statement. No alternative analysis is posted.

Why do the posted counts not provide a comparative test?

A statistical comparison normally requires a defined contrast between groups and an approach to uncertainty. The registry lists 0 analyses and does not post a p-value, confidence interval, or comparative effect estimate for implant passing. It is therefore not appropriate to present the counts as a statistically established difference. The group counts can be described plainly, but calculating or inferring a formal test result from them would go beyond the posted analyses. The record also describes the reference group as intended for reference and safety, rather than as a comparative test article.

As a general concept, model choice for binary outcomes depends on the design, sample size, event frequency, and estimand of interest. Standard large-sample approximations may perform poorly when data are sparse. Exact methods can sometimes be considered for sparse binary data, but they do not overcome the fundamental lack of information in a very small sample. The registry does not report a model or analysis method for the posted primary outcome, so no specific method should be attributed to the study.

What can be learned from the secondary outcomes?

The record lists 7 secondary outcomes, including successful closure, vaginal cuff healing, comparisons of implant passing and adverse events, implant-passing events considered to affect patient safety, and follow-up measures for dyspareunia and pain. These outcomes address different aspects of performance and safety, and they are not interchangeable with the primary implant-passing endpoint. Their results are not reported in the registry record. A reader cannot infer those outcomes from the primary counts.

In general, multiple outcomes can raise a multiplicity concern: when many hypotheses are tested, the chance of at least one apparently notable finding can increase unless the analysis plan addresses that issue. Whether an adjustment is appropriate depends on the trial’s objectives and prespecified analysis strategy. The registry does not report a multiplicity strategy or a detailed statistical analysis plan. Because no analyses are posted, there is no reported testing framework to evaluate.

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("Test Article - Zip-stitch Clips", "Reference Group - VICRYL Suture")
n      <- c(1, 1)
events <- c(0, 1)
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  Test Article - Zip-stitch Clips  1  0  0.0  0.0  97.5  0.0  79.3  1.3  84.2
ARM  Reference Group - VICRYL Suture  1  1  100.0  2.5  100.0  20.7  100.0  15.8  98.7

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 9 outcome measures and 7 secondary outcomes, in addition to the primary endpoint. The secondary measures concern closure success, vaginal cuff healing, implant passing, safety-impacting implant-passing events, adverse events, dyspareunia, and pain at follow-up. Their presence indicates that the study intended to assess more than the primary event count, but their results are not reported in the registry record. The posted primary outcome cannot be used as a substitute for these missing secondary results.

As a general statistical concept, examining multiple outcomes can create multiplicity: the more statistical comparisons considered, the greater the opportunity for a result to appear notable by chance. A planned approach can prioritize outcomes, define a testing sequence, or adjust inference, depending on the scientific aim. The registry does not report whether such an approach was specified or used. It lists 0 analyses, so there is no posted multiplicity procedure to assess.

The record says the primary data were analyzed “as-treated,” but does not provide further detail about analysis populations, exclusions, missing observations, or how incomplete follow-up was handled. Those details are not reported in the registry record. The endpoint timeframe is six weeks post-operative, but the record does not describe whether both participants completed follow-up or whether any outcome assessments were unavailable. Missingness should not be assumed to be absent merely because counts are posted.

The sample-size justification, interim analysis plan, and detailed statistical analysis plan are not reported in the registry record. These omissions matter because they prevent assessment of how the planned analyses and outcome hierarchy were intended to guide interpretation. The record’s termination status also lacks an explanation. Without these details, the posted data can be described but the analysis process cannot be fully evaluated.

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 0% reporting threshold.

Most frequent non-serious adverse event terms

The adverse-event record lists 1 participant at risk for serious adverse events in each group, with 0 serious adverse events in the Zip-stitch group and 0 in the reference group. It also lists 0 deaths in each group. These are counts from the participants represented in the registry’s safety record, not estimates of event rates with established precision.

For other adverse events, the Zip-stitch group has 1 participant at risk and 1 affected participant; the reference group has 1 participant at risk and 0 affected participants. The record does not provide the event term for that other adverse event. The top serious-event terms list is empty. The nature, timing, severity, and relationship of the other event to the device or procedure are not reported in the registry record.

As a general statistical concept, observing no serious events in a small group does not establish that serious events cannot occur. Rare or uncommon outcomes require much more information to characterize reliably. Likewise, a single other adverse event in a group does not by itself establish a comparative safety difference. The reference intervention is also named inconsistently in the record, which limits interpretation of the group labels.

The safety counts should therefore be read narrowly: the registry reports no serious adverse events or deaths in either listed group, and reports one participant with an other adverse event in the Zip-stitch group and none in the reference group. These figures do not provide a comprehensive safety profile or a precise comparison.

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

The result supports a limited descriptive statement about the primary endpoint: within six weeks after laparoscopic vaginal cuff closure, the registry reports 0.0 participants with implant passing in the Zip-stitch group and 1.0 in the reference group. Each group is listed with 1.0 participant. These are the posted counts, not a reliable estimate of the event frequency in a broader population.

The result does not establish that one closure approach is more effective or safer than the other. The registry posts 0 analyses and does not provide an inferential comparison, confidence interval, or detailed statistical analysis plan. The reference group is described as being for reference and safety rather than as a comparative test article. In addition, its intervention is named as V-LOC in the study summary and arm description but as VICRYL or Vicryl Suture in the outcome and safety records. These features make a definitive head-to-head interpretation inappropriate.

The posted primary count also does not answer every clinical question named in the registry. Outcomes for successful closure, cuff healing, other implant-passing measures, adverse events, dyspareunia, and pain are not reported in the registry record. The primary endpoint should not be used to infer those results.

As a general statistical concept, a study can produce a count without producing a precise estimate. A treatment effect estimate describes a contrast, while an uncertainty interval helps characterize how imprecisely that contrast is measured. Neither a comparative estimate nor an interval is posted for this endpoint. Randomized allocation and triple masking are recorded, but those design labels do not compensate for the limited amount of outcome information or the missing methodological detail.

The enrollment of 2 and terminated status place a clear boundary around interpretation. The record does not state why the study was terminated or provide a sample-size justification. The posted observations are informative as a record of what was counted among the participants, but they do not establish the expected performance of the device, rule out potential harms, or support generalization to other patients or settings.

14. Why This Trial Matters Statistically

This study matters statistically because it illustrates the difference between recording an endpoint and estimating an effect with useful precision. The registry identifies a specific primary outcome, a six-weeks post-operative timeframe, and group counts. Yet enrollment is 2, with one participant listed in each group. Those details sharply limit how much the counts can tell readers about event frequency beyond the participants observed.

The record also shows why design labels need context. Randomized allocation and triple masking are important features to report, but the registry does not explain the allocation process or who was masked. With so little outcome information, readers cannot assess the practical balance achieved between groups or the protection against bias in outcome assessment. The reference intervention’s inconsistent naming adds a further interpretive obstacle.

Another statistical lesson is that a count is not the same as a comparison. The posted values are descriptive, while the registry lists 0 analyses and provides no inferential estimate or uncertainty interval. Without those, the observed difference in counts should not be treated as evidence of a stable difference in the underlying populations. More elaborate statistical methods cannot create information that is absent from the observations.

The registry lists a broad set of secondary outcomes, but their results are not reported in the registry record. This underscores the value of complete outcome reporting: readers need to know not only the primary result, but also what was found for the other planned measures and how they were analyzed. The registry also does not report the reason for termination or the study’s own sample-size rationale.

Overall, the trial is a useful case for careful calibration of claims. Its posted data can be stated exactly, while the uncertainty and missing methodological context should remain visible. That distinction is central to responsible interpretation of small clinical studies.

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 central limitation is the small enrollment: the registry lists 2 participants, with 1.0 participant in each primary outcome group. This leaves very little information for estimating how frequently implant passing occurs or for comparing groups. A single participant’s outcome determines the posted count in each arm. No uncertainty interval or inferential analysis is reported.

The study is marked terminated, but the reason for termination is not reported in the registry record. The record also does not report a sample-size justification, interim analyses, or a detailed statistical analysis plan. Consequently, it is not possible to determine from the record whether enrollment or follow-up differed from the study’s original plans, or how the planned analyses were intended to handle sparse results.

The comparator description is inconsistent. The study summary and arm description refer to V-LOC barbed suture, while the primary outcome and adverse-event records identify VICRYL or Vicryl Suture. The arm description further states that the reference group was for reference and safety and would not be comparative against the test article. These details limit confidence about how to characterize the group contrast.

Other methodological details are not reported in the registry record, including eligibility criteria beyond the procedure context, participant characteristics, the randomization procedure, who was masked, the operational definition of implant passing, and the completeness of follow-up. The primary analysis is described as as-treated, but no additional analysis-population detail is given.

Finally, the record lists 7 secondary outcomes but does not post their results, and it lists 0 analyses. The safety data are also sparse, with event counts drawn from one participant per listed group. These limitations mean the registry supports only a narrow description of the recorded primary outcome and safety counts, not broad conclusions about efficacy or safety.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Zip-Stitch™ for Vaginal Cuff Closure in Laparoscopic Hysterectomy - Safety & Efficacy Study — NCT04081727.
• Registry record last updated 2022-09-07; status last verified 2022-08.
• Results first posted 2022-09-07.
• 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

NCT04081727 is a randomized, triple-masked, parallel-group device study sponsored by ZSX Medical LLC. It evaluated Zip-stitch clips for vaginal cuff closure during laparoscopic hysterectomy. The registry lists enrollment of 2, a start date of 2019-11-06, a primary completion date of 2020-08-31, and status as terminated.

The primary endpoint was the number of participants with implant passing within six weeks after surgery, analyzed as-treated. The registry reports 0.0 participants with the event among 1.0 participant in the Zip-stitch group and 1.0 among 1.0 participant in the reference group. No inferential analysis is posted. The record lists 9 outcome measures, 7 secondary outcomes, and 0 analyses.

The reference intervention is named inconsistently: the study summary and arm description say V-LOC barbed suture, while the posted outcome and safety records say VICRYL or Vicryl Suture. The reason for termination, sample-size justification, detailed statistical plan, and secondary outcome results are not reported in the registry record. The posted counts should be interpreted as descriptive observations from a very small enrolled sample.