TRANSFIX Zenith® Transection Clinical Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for TRANSFIX Zenith® Transection Clinical Study (NCT01688050), a na na study. The primary outcome is All-cause Mortality.

2. Clinical Question

TRANSFIX examined the use of the Zenith® TX2® Low Profile Endovascular Graft for blunt thoracic aortic injury. The registry describes the study as assessing the device’s safety and effectiveness. Its primary endpoint was all-cause mortality at 30 days. The record also includes adverse-event information for the Endovascular Repair group.

The clinical question can be framed as: among participants receiving endovascular repair with this device, what outcomes were recorded, including all-cause mortality by 30 days and adverse events? The record identifies a single study group, rather than a randomized comparison between the device and a control treatment. It therefore describes outcomes in the treated group but does not establish a comparative treatment effect against another group.

The registry reports an enrollment of 50. It also states that one death was adjudicated as unrelated by the Clinical Events Committee. However, a numerical result for the primary 30-day all-cause mortality endpoint is not reported in the registry record. The timing of the death mentioned in the adjudication note is not specified, so that note should not be treated as the primary endpoint result.

For safety, the record reports the number of participants with serious adverse events and with other adverse events in the Endovascular Repair group, alongside a list of commonly reported serious adverse-event terms. These counts describe events recorded in the study group. Without a like-for-like control group, they do not establish whether the frequency of an event was higher or lower than it would have been under another treatment or without the device.

3. Trial Design

TRANSFIX is registered as a single-group clinical study of the Zenith® TX2® Low Profile Endovascular Graft for blunt thoracic aortic injury. The registry lists the intervention as a device and the study arm as Endovascular Repair. Enrollment is recorded as 50. The study status is completed. The registry lists a start date of 2013-01-23 and a primary completion date of 2014-06.

The allocation field is recorded as NA, and masking is listed as none. The study model is single group. These entries do not describe a randomized assignment to different treatments. In particular, the record does not provide a like-for-like control arm against which the outcomes in the Endovascular Repair group can be directly compared.

The registry identifies three outcome measures and three analyses, but details of the other outcome measures and the specific analyses are not reported in the registry record. The primary outcome is all-cause mortality, measured in participants, with a 30-day timeframe. The record’s description notes that one death was adjudicated as unrelated by the Clinical Events Committee, but the numerical result for the primary endpoint is not reported in the registry record.

The registry identifies Cook Research Incorporated as the sponsor and describes the study as approved by the US FDA. It does not report the protocol’s rationale for its design or enrollment, detailed eligibility criteria, the complete follow-up schedule, or the statistical analysis plan. A separate planning illustration uses assumptions for a hypothetical two-arm comparison; those assumptions are not a description of the single-group trial design or evidence that the trial was planned as a comparative study.

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: One death was adjudicated as unrelated by the Clinical Events Committee (CEC).

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 All-cause Mortality, measured over 30 days.

The primary endpoint is all-cause mortality, expressed as a number of participants and assessed at 30 days. All-cause mortality counts deaths without restricting the endpoint to deaths judged to have a particular cause. This makes the endpoint a direct measure of mortality over the specified period and avoids relying on attribution of cause as part of the endpoint definition.

For interpretation, a numerical endpoint result would ordinarily indicate how many participants experienced the outcome within the stated timeframe. The registry record does not report that numerical result. It does note that one death was adjudicated as unrelated by the Clinical Events Committee. That adjudication note does not provide the 30-day all-cause mortality result: the timing of the death is not stated, and the endpoint is all-cause mortality regardless of whether a death is considered related to the intervention.

Because this is a single-group study, the endpoint can describe mortality recorded among participants in the study, but it cannot on its own show how mortality compares with an alternative treatment or with no intervention. Interpretation also depends on how the endpoint was defined and assessed in the full protocol, which is not reported in the registry record. The stated 30-day timeframe should therefore be kept distinct from other follow-up periods that may have been used for safety reporting.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

For a binary outcome such as whether a participant experienced an event, the basic descriptive result is a count of participants with the event. The registry’s primary endpoint is expressed as a number of participants, and its safety results include counts of participants with serious and other adverse events. Such counts are straightforward summaries, but they require a clear denominator and an outcome timeframe to be interpreted fully. The registry provides at-risk counts for the reported adverse-event group, while the primary endpoint’s numerical result is not reported in the registry record.

What does a confidence interval add?

As a general statistical explanation, a confidence interval describes the uncertainty around an estimate. A count or proportion observed in a study is not necessarily the exact value that would be observed in every similar group. An interval gives a range of values compatible with the data under the method used. Its width is affected by the amount of information and by the analysis method. A narrow interval indicates greater precision than a wide interval, but neither width nor interval alone establishes a causal treatment effect. Confidence intervals for the primary endpoint are not reported in the registry record.

Why does the study design matter?

General statistical interpretation distinguishes descriptive outcomes from comparative effects. In a single-group study, the observed event counts describe the enrolled group. A treatment comparison requires an appropriate comparator and a method for accounting for how participants entered each group. Random allocation can help balance prognostic factors on average, whereas a single-group design does not provide that protection through randomization. The registry lists allocation as NA and the model as single group, so a randomized treatment contrast is not available from this record.

This does not make descriptive counts uninformative. They can document what outcomes were recorded in the study group and support transparent reporting. But without a comparison group, the counts cannot show what would have happened to the same participants under another strategy. Differences from an external benchmark, if considered, would be vulnerable to differences in participant characteristics, care, outcome definitions, and follow-up. No such benchmark comparison is reported in the registry record.

How should the event terms be interpreted?

The record lists several serious adverse-event terms with percentages. As a general principle, a term-specific percentage should be interpreted according to its denominator and counting rules. Participants may experience more than one event, and the same participant may appear under more than one term. The registry information does not explain whether these terms represent participants, event occurrences, or a specific coding convention. It also does not state whether the listed terms are exhaustive. Therefore, the terms and percentages describe the posted entries, but cannot safely be combined into a total or treated as mutually exclusive categories.

Over-dispersion is a general concern when observations vary more than a simple statistical model assumes. For event data, repeated events in the same person or clustering among participants can create dependence and greater variability than a model allowing only independent observations would imply. This can make uncertainty estimates too optimistic if the analysis ignores that structure. The registry record does not report whether recurrent events were analyzed, whether clustering was considered, or whether the listed safety figures count individuals or event occurrences. It is therefore not possible to assess these modeling choices from the registry information.

What do the planning assumptions represent?

The registry describes planning illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two hypothetical arms, and a normal approximation. The effect to detect is described as a stated fraction of the observed effect. For time-to-event outcomes, the stated planning quantity is the total number of events; for other outcomes, it is participants per arm. These are planning illustrations, not the design of the registered single-group study, and not observed power. The registry does not report a sample-size justification for the actual trial or identify the assumptions behind its original enrollment target.

In general, a sample-size calculation estimates the amount of information a future study would need under specified assumptions. It does not show that the current study had a particular probability of detecting an effect after the results are known. Such a calculation is only as relevant as its assumptions, including the outcome definition, effect size, allocation, variability, and analysis. The planning assumptions described in the registry are not a substitute for the unreported protocol rationale or a comparative analysis plan for TRANSFIX.

Finally, a statistical analysis plan typically specifies the analysis population, endpoint handling, models, missing-data rules, and any planned adjustments. Those details are not reported in the registry record. Without them, the descriptive counts can be stated, but the exact inferential procedure and its assumptions cannot be independently assessed from the registry information.

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("Endovascular Repair")
n      <- c(50)
events <- c(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  Endovascular Repair  50  1  2.0  0.1  10.6  0.4  10.5  0.5  10.4

11. Multiplicity, Missing Data and Analysis Populations

The registry identifies three outcome measures and three analyses, but the specific outcomes and analyses beyond the primary endpoint are not reported in the registry record. It also does not report whether any outcomes were designated as secondary or exploratory, or whether a hierarchy was specified for interpreting them.

When a study evaluates multiple outcomes or performs multiple statistical tests, the chance of finding at least one apparently notable result can increase. As a general statistical principle, a prespecified testing strategy or adjustment may be used to address multiplicity. The record does not state whether the trial used such a strategy, so no conclusion about multiplicity adjustment can be drawn.

The primary endpoint is identified as all-cause mortality at 30 days, but its numerical result is not reported in the registry record. The record also does not state the number of participants with endpoint data, how missing outcome information was handled, or whether analyses followed an intention-to-treat or another analysis-population definition. Enrollment of 50 should not be assumed to equal the number analyzed for every outcome.

The record does not provide details on exclusions, withdrawals, loss to follow-up, censoring, or imputation. These are important because missing outcomes can affect both the estimated event frequency and the interpretation of uncertainty. The available adverse-event at-risk counts describe the denominators recorded for those outcomes, but do not supply a general account of missing data across all endpoints. In the absence of these details, the completeness and analysis population for the primary endpoint cannot be assessed.

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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: pneumonia (18.0%), vascular pseudoaneurysm (8.0%), arrhythmia (6.0%), multiple organ dysfunction (6.0%), acute respiratory distress syndrome (6.0%).

For the Endovascular Repair group, the registry reports serious adverse events in 30 of 50 participants at risk and other adverse events in 21 of 50 participants at risk. The record also lists seven deaths. The timeframe and endpoint relationship for those deaths are not reported in the registry information, so they should not be assumed to be the 30-day primary endpoint count.

The listed serious adverse-event terms are Pneumonia at 18.0%, Vascular Pseudoaneurysm at 8.0%, Arrhythmia at 6.0%, Multiple organ dysfunction at 6.0%, Acute respiratory distress syndrome at 6.0%, and Anaemia at 4.0%. These are registry percentages associated with the listed terms. The record does not clarify whether the percentages count participants or occurrences, whether participants could appear under multiple terms, or whether the list includes all serious events. Accordingly, they are not components that can be summed to obtain a total.

Serious adverse events and other adverse events are safety descriptions, not proof that the intervention caused an event. The registry information does not report an adjudication of causality for these event counts or a comparison group. The figures describe what was recorded in the study group; they do not establish a comparative safety profile.

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

The posted results establish that TRANSFIX was registered as a completed, single-group study of the Zenith® TX2® Low Profile Endovascular Graft for blunt thoracic aortic injury, with enrollment of 50. The record identifies all-cause mortality at 30 days as the primary endpoint and provides adverse-event counts for the Endovascular Repair group. It also notes that one death was adjudicated as unrelated by the Clinical Events Committee.

The primary endpoint’s numerical result is not reported in the registry record. The committee note cannot stand in for that result because the note does not specify the death’s timing relative to the endpoint or provide a complete endpoint count. The record therefore does not support a numerical conclusion about 30-day all-cause mortality.

The serious and other adverse-event counts, listed event terms, and deaths are descriptive information. They do not establish that the device caused or prevented an event, nor do they indicate how outcomes would compare with another treatment. The design is single group, and the registry does not include a randomized comparator. Comparisons with an unreported or external group would require additional information and assumptions that are not part of the registry record.

More broadly, a study result is interpreted in light of its endpoint definitions, analysis population, follow-up, missing data, and uncertainty. Several of these details, including confidence intervals and the analysis plan, are not reported in the registry record. Thus, the available information supports a limited description of recorded outcomes, not a complete assessment of precision or a causal treatment effect. The planning illustrations described in the record concern hypothetical sample-size calculations and should not be mistaken for observed power or evidence of a comparative result.

14. Why This Trial Matters Statistically

This study is statistically notable because its design and registry results illustrate the distinction between documenting outcomes and estimating comparative effects. A single-group study can record mortality and adverse events among participants receiving a device. Without a control group, however, it cannot provide a randomized estimate of how those outcomes differ from an alternative treatment.

The registry’s primary endpoint is clearly identified as all-cause mortality at 30 days, but the numerical result is not reported in the registry record. This gap matters: defining an endpoint does not by itself provide the result needed to assess its observed frequency or precision. The committee note about one death being adjudicated as unrelated supplies context about attribution, but does not fill in the endpoint result.

The safety counts also show why denominators, timeframes, and event definitions matter. The record gives at-risk counts for serious and other adverse events, but does not explain all counting rules for the listed terms. Without that detail, term-specific percentages should not be added or interpreted as distinct categories. The record’s seven deaths likewise cannot be linked to the primary 30-day endpoint without a stated timeframe.

Finally, the planning assumptions for hypothetical two-arm comparisons are distinct from the registered single-group design. Keeping those purposes separate prevents a planning calculation from being misread as trial evidence. The record is useful for describing the registered study and selected safety outcomes, while its missing endpoint and analysis details constrain statistical interpretation.

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 registry record does not report a numerical result for the primary endpoint of all-cause mortality at 30 days. Although it notes that one death was adjudicated as unrelated by the Clinical Events Committee, the note does not specify the timing of that death or provide the endpoint count. The seven deaths recorded for the Endovascular Repair group are not accompanied by a timeframe that would link them to the primary endpoint.

The single-group design is a central limitation for comparative interpretation. The record does not describe a randomized control group, so it cannot provide a like-for-like comparison of outcomes under another treatment. Outcomes among participants may reflect the injury, other care, participant characteristics, and other influences as well as the intervention; the registry information cannot separate these explanations.

Important details are not reported in the registry record, including the complete eligibility criteria, the analysis population, the statistical analysis plan, confidence intervals, missing-data handling, and the follow-up schedule for outcomes other than the stated primary timeframe. The exact counting and coding rules for serious adverse-event terms are also not described in the available information. These omissions restrict assessment of precision, completeness, and consistency of outcome ascertainment.

The registry identifies three outcome measures and three analyses, but does not describe their full content or any multiplicity strategy. Nor does it report the rationale for the actual enrollment or a protocol-based sample-size calculation. The separate planning assumptions concern hypothetical two-arm comparisons and should not be treated as evidence about the original design or observed statistical power.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: TRANSFIX Zenith® Transection Clinical Study — NCT01688050.
• Registry record last updated 2020-11-18; status last verified 2020-10.
• Results first posted 2015-11-18.
• 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

TRANSFIX is a completed, single-group study of the Zenith® TX2® Low Profile Endovascular Graft for blunt thoracic aortic injury. The registry lists enrollment of 50, no masking, and Endovascular Repair as the study group. The primary endpoint is all-cause mortality at 30 days, but its numerical result is not reported in the registry record.

The record notes that one death was adjudicated as unrelated by the Clinical Events Committee. For the Endovascular Repair group, it reports serious adverse events in 30 of 50 participants at risk, other adverse events in 21 of 50 at risk, and seven deaths. The listed serious adverse-event terms include Pneumonia, Vascular Pseudoaneurysm, Arrhythmia, Multiple organ dysfunction, Acute respiratory distress syndrome, and Anaemia.

Because the study is single group, the posted outcomes are descriptive and do not provide a randomized comparison. The statistical analysis plan, confidence intervals, missing-data handling, and additional outcome details are not reported in the registry record.