Safety and Performance of the COR-VG-001 Conduit in Pediatric Patients for Extracardiac Total Cavopulmonary Connection: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Performance of the COR-VG-001 Conduit in Pediatric Patients for Extracardiac Total Cavopulmonary Connection (NCT02377674), a na na study. The primary outcome is The Number of Graft Related Post-operative Complications That Require a Repeat Surgery or a Non Surgical Treatment Within 12-month Post Implantation..

2. Clinical Question

The question is principally about safety during follow-up after implantation, rather than a comparative estimate of benefit against another conduit or procedure. The record identifies the device as the intervention and describes the intended surgical setting, but it does not report the primary outcome result or a detailed analysis population. Consequently, the record does not establish how frequently the defined primary complications occurred, how complete follow-up was, or how the observed safety experience compares with another treatment. The posted adverse-event summaries offer additional safety context, but those event categories should not be treated as equivalent to the specifically defined primary endpoint.

3. Trial Design

This was a completed, single-group device study of the COR-VG-001 conduit in pediatric patients undergoing extracardiac total cavopulmonary connection. The registry lists enrollment of 5 participants. The study's phase and allocation are both recorded as NA, and masking is listed as none. The record identifies Xeltis as the sponsor. It gives a start date of 2013-10 and a primary completion date of 2015-09.

The intervention is a surgically implanted vascular graft for the extracardiac connection. The registry description explains that an extracardiac Fontan procedure routes venous blood from the inferior vena cava to the pulmonary arteries without passing through the morphologic right ventricle. It describes the graft as a biodegradable prosthesis intended for use as an extracardiac conduit. These descriptions establish the clinical and device context, but do not report comparative effectiveness against another conduit.

Because there is no concurrent control group, the study can describe outcomes observed among participants receiving the device, but it cannot by itself estimate a treatment contrast against usual care or another device. Allocation is not a randomization method in this record, and the study is explicitly identified as not being a randomized comparison. A before-and-after contrast, historical comparison, or other external comparator is not reported in the registry record.

The record lists two outcome measures, including the primary safety outcome and a secondary measure concerning grafts with reduced function postoperatively. It does not report results for the primary outcome in the registry record for this analysis. Nor does it report the secondary outcome result, a detailed protocol, or the statistical analysis plan. Thus, enrollment, design, follow-up intent, and the available safety summaries can be described, but the study's planned analytic procedures and the primary endpoint findings cannot be reconstructed from the registry record.

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

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 The Number of Graft Related Post-operative Complications That Require a Repeat Surgery or a Non Surgical Treatment Within 12-month Post Implantation., measured over 12 months.

The primary endpoint is the count of participants with graft-related postoperative complications requiring repeat surgery or nonsurgical treatment within 12 months after implantation. The outcome description further characterizes the safety assessment as including complications requiring surgery or intervention, or leading to death. This endpoint focuses on clinically consequential events linked to the graft, rather than on every postoperative symptom or abnormal finding.

Counting participants with an event is a direct way to summarize how many people meet the endpoint definition during the stated follow-up period. It can make a safety outcome easier to interpret than a count of every event when an individual could experience multiple complications. However, the registry record does not clarify all operational details, such as how graft relatedness was adjudicated, how repeat events in one participant were handled, or how the difference between the endpoint title and description was resolved.

The endpoint is relevant to an early safety assessment because it captures complications serious enough to prompt treatment or intervention, and includes death in the description. It is not a general measure of all device performance, and it does not directly quantify hemodynamic performance or longer-term tissue formation. The registry record does not report the observed primary endpoint count, so no event frequency or precision estimate for this outcome can be stated.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record describes a single-group study with no masking and no randomized comparison. That design determines what statistical conclusions are available. A single-group summary can describe events among participants who received the graft, but a treatment effect is inherently comparative: it asks how outcomes differ between intervention and comparator conditions. Because no concurrent comparator is reported, the registry record cannot estimate such a contrast. This is a general distinction between descriptive and comparative analyses.

What does a count of participants with an event mean?

The primary outcome is framed as a count of participants meeting a specified complication definition during 12 months after implantation. A participant-based count focuses on whether each person experienced an event meeting the definition, rather than counting every event occurrence. This can prevent repeated events in one person from being mistaken for events in separate people. However, interpretation depends on the precise rules for classifying events and participants. The registry record does not report detailed adjudication rules, how multiple complications in one participant were handled, or whether follow-up was complete for all participants.

The outcome title and its description are not identical in wording. The title refers to repeat surgery or nonsurgical treatment; the description refers to surgery, intervention, or death. These may be related formulations, but the registry record does not explain how they were reconciled in the analysis. This is an endpoint-definition limitation: a reader needs a consistent operational definition to know which events count and to reproduce an analysis.

Why is there no treatment-effect estimate?

A comparative effect requires outcomes under at least two conditions, or an explicitly defined external comparison. This study is identified as single-group, and the record does not provide a control arm. There is therefore no randomized contrast, no between-group estimate, and no basis in the registry record for calculating a relative effect. Even if the observed outcomes were available, a single-group result would remain descriptive unless a defensible external benchmark and its assumptions were specified. Such a benchmark is not reported.

Randomization is useful in comparative trials because it can balance measured and unmeasured prognostic factors on average across assigned groups. It does not guarantee balance in every trial, but it supports a less biased comparison when implemented and analyzed appropriately. Here, allocation is listed as NA and the study is not a randomized comparison. Statistical adjustment cannot be assumed to solve that design limitation; the registry record does not report an adjusted analysis or the variables that might have been used.

What do uncertainty measures add?

A confidence interval is a general statistical tool for expressing the uncertainty around an estimated quantity. For an event proportion, an interval communicates that the observed proportion is an estimate subject to sampling variability. With a small group, uncertainty can be substantial, particularly for rare outcomes. An interval does not remove design limitations, establish causation, or account automatically for missing follow-up. The registry record does not report a confidence interval for the primary endpoint or an inferential analysis, so no interval can be interpreted for that outcome.

Likewise, a p-value would address compatibility between data and a specified statistical model or null hypothesis; it would not measure the probability that the device is safe or effective. No primary endpoint p-value or hypothesis test is reported in the registry record. In a single-group study without a specified comparator or benchmark, a conventional between-group test would not be appropriate to infer a comparative effect.

How should the sample-size illustrations be read?

Any sample-size planning illustrations associated with this analysis are hypothetical planning exercises, not observed power and not the original study's design justification. The stated assumptions use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is expressed as a fraction of the observed effect. For time-to-event calculations, the stated quantity is total events; other calculations refer to participants per arm. These assumptions do not change the actual single-group design of the study.

A sample-size illustration describes the scale of a hypothetical future comparison under chosen assumptions. Its result depends on the assumed effect, variability, allocation, statistical test, and desired power. It does not show that the original study had adequate power, and it is not a substitute for a prespecified design rationale. The registry record does not report the trial's own sample-size justification, statistical plan, interim analyses, or a randomized comparison. No additional assumption about these matters can be inferred.

Why can event summaries differ from the primary endpoint?

Adverse-event summaries and a protocol-defined endpoint can use different inclusion rules. The adverse-event report may cover events irrespective of whether they were graft-related, required the treatment specified for the primary endpoint, or occurred within the endpoint's defined time window. The primary endpoint may exclude events that do not satisfy its criteria. Since the registry does not provide participant-level event linkage or endpoint adjudication, the adverse-event summaries cannot be used to reconstruct the primary outcome.

Over-dispersion is a general concern when outcome variation exceeds what a simple statistical model assumes. It can arise in clustered or recurrent-event data, for example, when some participants experience many events while others experience few. A participant-level binary outcome avoids treating recurrent events as independent observations, but recurrent-event analyses may still need to account for within-participant dependence. The registry record does not report such an analysis, and no conclusion about over-dispersion in this study can be made from the aggregate figures.

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("Vascular Graft, Model COR-VG-001")
n      <- c(5)
events <- c(0)
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  Vascular Graft, Model COR-VG-001  5  0  0.0  0.0  52.2  0.0  43.4  0.4  45.9

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists two outcome measures: the primary graft-related postoperative complication outcome and a secondary measure concerning grafts with reduced function postoperatively. It does not report a statistical analysis plan, a multiplicity adjustment, or the results for the secondary measure. Without that information, it is not possible to determine whether multiple outcomes or analyses were handled under a prespecified testing strategy. In general, testing multiple hypotheses can increase the chance of a false-positive finding if the analysis does not account for multiplicity; whether that issue affected this study cannot be assessed from the record.

The record reports no analyses in the registry entries and does not provide a primary endpoint result. It also does not describe an interim analysis or an analysis population such as intention-to-treat or per-protocol. These details are not reported in the registry record and should not be inferred from the completion status or adverse-event summaries.

Missing outcome data are another potential source of uncertainty. The registry reports enrollment and adverse-event denominators, but does not report endpoint-specific completeness, losses to follow-up, exclusions, or missing-data methods. It is therefore not possible to determine whether every enrolled participant contributed information to the primary endpoint or how missing outcomes, if any, were handled. A denominator in an adverse-event summary does not establish completeness for a separate endpoint with its own follow-up and definition.

As a general matter, missingness can affect an estimate when the chance of having an observed outcome is related to a participant's health status or outcome. Methods for handling missing data require assumptions, and different assumptions can produce different interpretations. No missing-data approach is reported, so the primary endpoint's susceptibility to this issue cannot be 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 serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: pleural effusion caused by cardiac failure (40.0%), left lower lobe pneumonia (20.0%), cardiac failure, poly seriositis nyha iii (20.0%), stenosis of conduit (20.0%), decreased lvef (20.0%).

The registry reports serious events among 4 of 5 participants at risk and other events among 4 of 5 participants at risk in the COR-VG-001 group. It reports 0 deaths. These are descriptive safety figures. They do not indicate how many participants met the primary endpoint, because the primary endpoint has specific criteria involving graft relatedness and the need for repeat surgery or nonsurgical treatment within 12 months. The adverse-event totals and the endpoint result should not be treated as interchangeable.

The serious-event terms listed include pleural effusion caused by cardiac failure (40.0%), left lower lobe pneumonia (20.0%), cardiac failure with poly seriositis NYHA III (20.0%), stenosis of conduit (20.0%), and decreased LVEF (20.0%). The registry record does not explain whether terms could occur in the same participant, how each event was judged related to the graft, or the denominator and coding details underlying each displayed percentage. The terms therefore should not be summed or treated as mutually exclusive categories.

Seriousness describes event classification, not necessarily causation by the device. The registry summary alone does not establish whether an event was caused by the graft, the operation, the underlying condition, or another factor. The small study group and absence of a control arm also limit comparisons with background event rates. The figures provide safety context, but they cannot establish a causal risk estimate.

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

The registry record establishes that the completed study evaluated the COR-VG-001 conduit in pediatric patients undergoing extracardiac total cavopulmonary connection. It also records a single-group design, enrollment of 5 participants, a primary safety endpoint defined around graft-related postoperative complications, and adverse-event summaries. This is useful descriptive context for an early device evaluation.

The principal result needed to answer the primary safety question is not reported in the registry record: the count of participants meeting the endpoint definition within 12 months. Without it, readers cannot determine the observed frequency of the specified complications from this record. The adverse-event summaries cannot fill that gap because their criteria may differ from the primary endpoint and no participant-level linkage is reported.

The reported event figures do not establish that the conduit caused the listed events. They also do not establish that events were unrelated to it. A single-group design cannot distinguish device-associated risk from risks related to surgery, the underlying congenital condition, or postoperative care. There is no concurrent control group to support a comparison, and the record does not report an adjusted or external comparison.

Absence of a reported primary endpoint result is not evidence that no primary events occurred. Similarly, a recorded count of 0 deaths does not establish the absence of other serious complications, as the registry separately reports serious adverse events. Each outcome has its own definition and should be interpreted on its own terms.

More broadly, a small safety study can describe what was observed among its participants but may not characterize uncommon outcomes precisely. That is a general limitation of small samples, not a numerical estimate beyond the registry figures. The study should be read as a limited, noncomparative safety experience; it does not establish comparative performance, long-term durability, or a treatment effect.

14. Why This Trial Matters Statistically

This study illustrates a basic distinction in clinical-trial interpretation: a safety question can be clinically important even when the design supports only descriptive evidence. The primary endpoint is focused on consequential postoperative complications, but a single-group study without a reported primary endpoint result cannot provide a complete estimate for that question. Clear outcome reporting is essential for readers to assess what was observed and how precisely it was estimated.

It also shows why design details matter alongside event counts. In a randomized comparison, a concurrent control group can help distinguish outcome differences associated with treatment assignment from differences in patient characteristics and background risk. This study has no such comparator. Its adverse-event summaries therefore describe the study group but cannot establish that the graft increased or reduced event risk relative to another option.

The registry also distinguishes an endpoint from broader adverse-event reporting. A defined endpoint may count only events meeting specific criteria, while safety summaries can include a wider range of events. Treating those summaries as interchangeable would obscure what the primary question actually measures. The mismatch in wording between the endpoint title and description further underscores the importance of a precise, reproducible definition.

Finally, the study highlights the limits of small early evaluations. Such studies can contribute preliminary information about device use and observed safety events, but they offer limited ability to characterize uncommon outcomes or make precise comparative claims. The statistical value of the record depends not only on its design, but also on transparent reporting of endpoint results, follow-up completeness, analysis methods, and event attribution. Several of these details are not reported in the registry record.

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 most direct limitation is that the registry record does not report the primary endpoint result, despite defining the outcome and follow-up period. Without the count of participants meeting the endpoint criteria, the principal safety question cannot be answered from the available record. The secondary outcome result concerning reduced graft function is also not reported in the registry record for this analysis.

The study is single-group, with allocation recorded as NA and no randomized comparison. The adverse-event summaries consequently cannot be interpreted as a treatment effect or compared causally with another procedure. The record does not describe historical controls, an external comparator, or an adjustment strategy that might support a broader comparison.

The enrollment of 5 participants limits how much can be learned about uncommon complications and makes descriptive outcomes sensitive to individual observations. This is a general statistical limitation, not a basis for estimating any unreported rate. The registry also does not report confidence intervals for the primary outcome, endpoint-specific follow-up completeness, missing-data handling, or analysis populations.

There is some ambiguity in the primary endpoint wording: its title refers to repeat surgery or nonsurgical treatment, while its description refers to surgery, intervention, or death. The record does not clarify how the endpoint was operationalized or adjudicated. The adverse-event summaries do not report enough detail to determine which events were graft-related or overlapped with the primary endpoint. These gaps restrict reproducibility and interpretation.

Further limitations include the absence of a reported statistical analysis plan, sample-size justification, interim-analysis information, and multiplicity strategy. These matters are not reported in the registry record. The described planning assumptions for hypothetical sample-size illustrations should not be mistaken for the original study's design rationale.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Safety and Performance of the COR-VG-001 Conduit in Pediatric Patients for Extracardiac Total Cavopulmonary Connection — NCT02377674.
• Registry record last updated 2020-11-10; status last verified 2020-10.
• Results first posted 2020-11-10.
• 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

NCT02377674 is a completed, single-group device study sponsored by Xeltis. It evaluated the COR-VG-001 conduit in pediatric patients undergoing extracardiac total cavopulmonary connection. The registry reports enrollment of 5 participants, masking as none, and allocation as NA. The study start is recorded as 2013-10 and primary completion as 2015-09.

The primary outcome concerns graft-related postoperative complications requiring repeat surgery or nonsurgical treatment within 12 months; the accompanying description also refers to intervention or death. The record does not report the observed primary endpoint count. It reports serious events for 4 of 5 participants at risk, other events for 4 of 5 at risk, and 0 deaths, with several serious-event terms listed. These safety summaries are descriptive and do not provide a controlled comparison or establish event causation.

The registry lists two outcome measures but does not report the secondary result, a detailed analysis plan, or endpoint-specific missing-data information. The available record therefore offers limited descriptive safety context rather than a complete estimate of the primary outcome or comparative evidence.