Liver Transplantation for Cholangiocarcinoma: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Liver Transplantation for Cholangiocarcinoma (NCT00708877), a na na study. The primary outcome is Transplant-related Mortality.

2. Clinical Question

The registry summary gives clinical context rather than results from this study. It describes the difficulty of achieving negative resection margins and cites earlier experience, including survival rates of 92%, 82%, and 82% at 1, 3, and 5 years after transplantation in a recent report. Those figures are background claims in the summary; they are not reported outcomes for this cohort. The record states that confirmation at other centers and optimal selection criteria remained uncertain. This study's single-group structure and absent primary outcome count leave those broader questions unresolved.

3. Trial Design

The record describes an interventional study with a single-group model. Its intervention is liver transplantation, and masking is listed as NONE. Allocation is NA, consistent with the record not describing a randomized allocation. The study is not a randomized comparison, so there is no like-for-like control group within the recorded design.

The registry lists enrollment as 5. That figure describes enrollment in the record; it should not be taken as the number analyzed for the primary endpoint, because the record does not report a primary outcome count or an analysis population count. The study status is TERMINATED. Its recorded start is 2007-03 and its primary completion is 2011-07. These dates and status describe the registry record; they do not explain why the study ended or whether the planned follow-up was completed.

The primary outcome is titled “Transplant-related Mortality,” uses participants as its unit, and has a 2-year timeframe. The record says the entire cohort was used for analysis, but gives no endpoint result and records no analyses. There is no reported comparator, allocation procedure, or masking beyond the listed values. Phase is recorded as NA. The sponsor is the University of Utah.

Important protocol details are not reported in the registry record. These include the criteria for selecting participants, the intended treatment regimen beyond the named procedure, the planned follow-up procedures, the target enrollment rationale, and the reasons for termination. The record also does not explain whether the study's design or data collection changed over time. These omissions limit interpretation of both the intended study and its reported status.

A single-group study can describe outcomes among people who received an intervention, but it cannot by itself isolate the intervention's effect from other influences. In general, differences in disease severity, selection, concurrent care, and follow-up can affect observed outcomes. Without a control group or a reported adjustment strategy, the design cannot estimate what would have happened to comparable participants under an alternative approach.

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: Entire cohort was used for analysis.

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 Transplant-related Mortality, measured over 2 years.

The primary endpoint is “Transplant-related Mortality.” It is expressed as a number of participants, with a timeframe of 2 years. The registry description says it was intended to determine mortality-related transplant outcomes, and it states that the entire cohort was used for analysis. The endpoint count is not reported in the registry record.

In general, a mortality endpoint records deaths according to a stated definition and follow-up period. A transplant-related mortality endpoint may be intended to focus attention on deaths considered related to the transplant, but the precise attribution rules matter: the registry record does not report how a death would be classified as transplant-related, how causes would be assessed, or how competing causes would be handled. The title and short description alone do not resolve those operational details.

A count is a direct way to report how many participants met a binary outcome definition. However, a count without a reported denominator, complete follow-up information, and outcome definition cannot establish the frequency of the event or how precisely it has been estimated. Although the record lists enrollment as 5, it does not give the primary endpoint result or state how many participants had outcome data available at the relevant follow-up. The registry record therefore identifies the intended outcome and timeframe, but not the evidence needed to interpret the observed mortality result.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The record labels the design as single-group and allocation as NA. These design features determine what statistical questions the data can address. A single-group outcome can describe what was observed among participants in that cohort, provided the outcome and follow-up are reported. It does not create a concurrent comparison. Consequently, the record cannot estimate a treatment contrast between transplantation and an alternative based on its design as registered.

What does a participant count mean?

The primary endpoint is a number of participants with a mortality-related transplant outcome, over a 2-year timeframe. For a binary endpoint, each participant is generally classified according to whether the defined event occurred within the specified period. Such a count is interpretable only with a clear event definition, a clear period of observation, and information about the participants whose status is known. The record does not provide the endpoint count, operational event definition, or missing-outcome accounting. The endpoint title does not reveal how attribution to transplantation was determined.

In general, counts and proportions answer different descriptive questions. A count reports the number of events; a proportion relates that count to an appropriate denominator. The registry record identifies the unit as participants and lists enrollment as 5, but does not report the outcome count or an endpoint denominator. No proportion should be inferred from those fields. Nor can a count be converted into a meaningful measure of risk without knowing the relevant population at risk and outcome ascertainment.

Why does the design matter?

Random allocation, when used and implemented appropriately, can help make comparison groups similar on average with respect to measured and unmeasured prognostic factors. This record does not report randomized allocation or a second group. In a single-group study, observed outcomes can be influenced by participant selection, disease characteristics, other care, and how follow-up is conducted. Statistical adjustment can address some measured differences in suitable data, but it cannot create a randomized comparator where none exists, and no adjusted model is reported.

Masking is listed as NONE. In general, masking concerns whether participants, clinicians, or outcome assessors know the assigned intervention or exposure. Its absence can matter when decisions or assessments involve judgment. For a mortality endpoint, the possibility of judgment may be particularly relevant to attribution of whether a death was transplant-related. The record does not describe outcome adjudication or other safeguards, so the practical implications of the masking entry cannot be assessed.

What do uncertainty measures require?

In general, an estimate is more informative when accompanied by a measure of uncertainty, such as a confidence interval. A confidence interval reflects uncertainty from sampling under specified statistical assumptions; it is not a guarantee that the true value lies within the interval, and it does not address every source of bias. A small study may yield imprecise estimates, but precision cannot be quantified from enrollment alone. This record reports neither an endpoint estimate nor an interval, and therefore offers no numerical measure of uncertainty for the primary outcome.

A hypothesis test, in general, evaluates data against a specified null hypothesis using a chosen statistical procedure. A p-value is not the probability that the null hypothesis is true and does not measure clinical importance. No hypothesis test or p-value is reported for the primary endpoint. The record lists 0 analyses, so no inferential result should be attributed to this study from the registry entry.

How should planning illustrations be interpreted?

The record's planning assumptions describe a generic illustration based on an observed effect: a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The planned effect is expressed as a stated fraction of the observed effect. These assumptions do not describe the registered single-group design, which has no two-arm allocation. Any sample-size figures derived under those assumptions would be planning illustrations, not observed trial results or evidence of achieved power. The record does not include a numerical observed effect or numerical planning results, so no particular sample size can be interpreted from it.

In general, planning calculations depend on the outcome, expected effect, variability or event rate, allocation, significance level, and desired power. Changing assumptions can change the calculated sample size. For binary outcomes, event rates and the outcome definition are especially important; for time-to-event outcomes, event counts and follow-up assumptions matter. A planning calculation is not evidence that a study was adequately powered, and a post hoc power calculation does not replace reporting an estimate and its uncertainty. The registry does not report a protocol-specific sample-size justification, so the generic illustration should not be treated as the study's original design rationale.

What can be concluded from the recorded analysis fields?

The record identifies the entire cohort as the population used for the primary analysis, but does not provide an analysis dataset description, missing-data method, or outcome result. In general, analysis populations should be defined transparently, and the handling of unavailable follow-up should be explained because exclusions can affect interpretation. A statement about the intended cohort does not reveal whether every enrolled participant had an observed outcome. With no reported analysis or result, there is no basis for recalculating a primary estimate, assessing model fit, or comparing a recalculated result with a sponsor 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("Transplant")
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  Transplant  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 1 outcome measure and 0 analyses. It does not report multiple primary endpoints or a set of statistical tests. Multiplicity arises when several outcomes, time points, subgroups, or comparisons are tested; repeated testing can increase the chance of a false-positive finding if the analysis does not account for it. Since no inferential analyses are recorded, there is no multiplicity adjustment to evaluate. The record also does not report a prespecified hierarchy of outcomes or an analysis plan, so it is not possible to assess whether the primary endpoint was selected before results were examined.

Missing data are a separate concern. The primary endpoint is defined over 2 years, but the record does not report follow-up completeness, the number with endpoint information, reasons for missing outcomes, or methods for handling missingness. In general, complete-case analysis can be biased if participants with missing information differ systematically from those observed. Imputation and other methods also rely on assumptions that should be described and assessed. No missing-data strategy is reported in the registry record.

The primary outcome description states that the entire cohort was used for analysis. This does not specify how the analysis treated participants whose endpoint status might not have been available. The record also does not provide a separate intention-to-treat or per-protocol definition. Without participant flow and analysis details, the meaning of the stated population cannot be fully evaluated. These gaps limit assessment of both completeness and the reliability of any implied endpoint estimate.

12. Safety Results

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

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The adverse-event record lists the Transplant group with 5 at risk for serious adverse events and 0 affected. It also lists 5 at risk for other adverse events and 0 affected. These are the event figures recorded in the registry. The record does not list serious adverse-event terms among the top serious terms. The deaths field is null, so a death count is not reported in the registry record.

“At risk” describes the group size recorded for the adverse-event category; “affected” is the recorded count with an event. These figures should be read as the registry's event reporting, not as proof that no adverse events occurred outside the recorded definitions, observation period, or reporting process. The record does not give the adverse-event observation window, event definitions, severity grading rules, relatedness assessments, or method of collection. It also does not explain whether participants with incomplete safety follow-up were included.

These safety counts are distinct from the primary endpoint. The primary endpoint is transplant-related mortality assessed at 2 years, and its count is not reported. The null deaths field for adverse events should not be used to fill in that missing primary outcome. The safety figures describe what is entered in the adverse-event fields; their scope and completeness cannot be determined from the available registry information.

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

The record establishes that a single-group study of liver transplantation for cholangiocarcinoma was registered, lists enrollment as 5, and records the study as TERMINATED. It identifies transplant-related mortality at 2 years as the primary endpoint. It does not report the primary endpoint count, a confidence interval, a statistical test, or any analysis. The central outcome therefore cannot be characterized from the posted results.

Even a reported count from this design would describe outcomes in the study cohort, not establish what would have happened under another treatment. A comparison requires a suitable comparator and an analysis that supports the intended contrast. This record describes neither a separate comparator group nor randomized allocation. In general, outcomes in a selected cohort can reflect participants' starting characteristics, the intervention, other care, and follow-up. The registry summary notes that selection criteria were an area of uncertainty, but does not give this study's criteria.

The earlier survival figures in the registry summary—92%, 82%, and 82% at 1, 3, and 5 years—are background information about a recent report, not findings from this study. They cannot be used as a substitute for this cohort's missing outcome data or as a direct benchmark without comparable populations, endpoint definitions, and follow-up methods.

The safety record lists 0 affected for the serious and other adverse-event categories, while the deaths field is not reported. These fields do not supply the missing primary mortality result and cannot be interpreted beyond their recorded categories and unspecified observation procedures. Overall, the registry record describes the study's basic design and intended endpoint but does not provide results sufficient to assess the outcome's magnitude, precision, or comparative meaning.

14. Why This Trial Matters Statistically

This study illustrates why a clearly named outcome is not the same as a reportable result. The registry specifies transplant-related mortality as a participant-count endpoint with a 2-year timeframe. Yet without the event count, denominator, endpoint definition, and follow-up accounting, readers cannot evaluate even the basic descriptive result. Statistical interpretation depends on the details connecting an outcome label to observed data.

The design also matters. A single-group study can contribute descriptive information about a cohort, but it cannot provide a controlled treatment contrast. This is important when the surrounding clinical question concerns whether a strategy improves outcomes relative to other care. Without a comparator, observed outcomes would remain open to explanations involving patient selection, underlying disease, concurrent treatment, or follow-up. The record's reference to uncertainty about selection criteria underscores why population definition is relevant to interpreting a cohort's experience.

The entry also demonstrates the distinction between study status and study results. TERMINATED is a status, not an explanation of why the study ended, whether follow-up was complete, or what outcomes occurred. Enrollment and adverse-event fields provide some recorded details, but they do not replace the missing primary endpoint analysis. Transparent participant flow, outcome ascertainment, and uncertainty estimates would be needed to assess precision and missingness.

Finally, generic planning assumptions should not be confused with a protocol-specific design or observed evidence. The record's planning framework uses an equal-allocation two-arm illustration, whereas the registered study is single-group. This contrast shows why statistical planning output must be interpreted in relation to the actual design. Without the underlying effect and numerical planning results, the illustration cannot establish what enrollment was justified or what the study could reliably detect.

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 primary limitation is that the registry record does not report the primary endpoint result. It identifies transplant-related mortality at 2 years but provides no event count, estimate, or uncertainty measure. This prevents assessment of the outcome's frequency or precision.

The design is single-group, with no separate comparator and allocation listed as NA. Any cohort outcome would therefore lack an internal control for comparison. The record does not report eligibility criteria, detailed participant characteristics, or a protocol-level description of the treatment strategy. Although the summary discusses radiotherapy and chemosensitization alongside transplantation, the intervention field names liver transplantation; the treatment actually received by participants is not described in enough detail to resolve that difference.

Follow-up and analysis details are also limited. The record does not report individual follow-up completeness, endpoint ascertainment procedures, missing-data handling, or reasons for termination. It lists the entire cohort as the primary analysis population, but does not give the number with primary endpoint data. No analysis is recorded, and no statistical plan or sample-size justification is reported in the registry record.

Safety information is limited to recorded at-risk and affected counts; observation periods, event definitions, grading, and attribution procedures are not reported. The deaths field is null. These omissions mean that the safety fields cannot clarify the missing primary mortality outcome. Finally, the background survival figures in the summary refer to earlier experience and cannot be treated as findings from this study or as a controlled comparison.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Liver Transplantation for Cholangiocarcinoma — NCT00708877.
• Registry record last updated 2013-07-30; status last verified 2013-07.
• Results first posted 2012-04-04.
• 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

The registry record describes an interventional, single-group study titled “Liver Transplantation for Cholangiocarcinoma,” sponsored by the University of Utah. The intervention is liver transplantation; allocation is listed as NA and masking as NONE. Enrollment is listed as 5. The study is TERMINATED, with start recorded as 2007-03 and primary completion as 2011-07.

The primary endpoint is transplant-related mortality, measured as a number of participants over 2 years. The record says the entire cohort was used for analysis, but the outcome count is not reported and 0 analyses are listed. The adverse-event entries record 0 affected among 5 at risk for serious events and 0 affected among 5 at risk for other events; a deaths count is not reported. The record does not provide a comparator, primary outcome estimate, or inferential analysis, so it does not establish a comparative treatment effect.