Use of Tachosil® for Lymph Sealing During Surgery: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Use of Tachosil® for Lymph Sealing During Surgery (NCT01920958), a registered phase not stated study. The primary outcome is Percentage of Participants With Post-Operative Seroma Formation Over Time as Determined at Hospital Discharge.

2. Clinical Question

3. Trial Design

This is a non-interventional study of TachoSil® for lymph sealing during surgery. The official title identifies it as a non-interventional study, and the registry lists a single TachoSil® group. Participants had lymphadenectomy and the patch was applied during surgery. The record does not describe a randomized allocation process; allocation is explicitly not stated. It also cautions that the arms are not a like-for-like control comparison. Accordingly, the study description should be read as an account of outcomes in participants who received the patch, not as a controlled estimate of the effect of choosing the patch over an alternative.

Enrollment was 233. The study start is recorded as 2012-09 and primary completion as 2014-03. The status is completed. The sponsor is Takeda. These details describe the registry record; they do not establish how many participants contributed data to each endpoint or whether all enrolled participants completed follow-up. Those details are not reported in the registry record.

The primary endpoint is postoperative seroma formation over time as determined at hospital discharge, with a timeframe of up to 50 days. Listed secondary outcomes cover surgeons’ ratings of handling, utility in the operation, and satisfaction using a 10-point numerical rating scale. They also include drainage insertion, changes in drainage stay and volume, hospital and ICU stay, and pharmacoeconomic outcomes based on operating time and hospital stay. The existence of these planned outcome topics does not establish that results were collected or reported for each of them.

The registry does not report a protocol-level statistical analysis plan, sample-size justification, interim analyses, or details of participant recruitment and follow-up beyond the endpoint description. No analysis records are listed. Thus, the design can be characterized as a completed, descriptive, non-interventional study, while important operational and analytical details remain unavailable in 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.

Before assignment: Collection of information of routine use of TachoSil® in participants who had lymph node surgery.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Intent-to-treat population consisted of all participants who received patient information, signed consent and had Tachosil® applied during lymph node surgery.

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: ITT population consisted of all patients who received patient information and who consented to the collection, transmission and evaluation of their data and who underwent lymph node resection with TachoSil®.

6. Primary Endpoint

The registry lists the primary outcome as Percentage of Participants With Post-Operative Seroma Formation Over Time as Determined at Hospital Discharge, measured over Up to 50 Days.

The primary endpoint is the percentage of participants with postoperative seroma formation over time, determined at hospital discharge. The listed timeframe is up to 50 days. This endpoint addresses whether seroma was recorded following lymph node surgery in participants whose operation included TachoSil® application. The registry describes the outcome as a number of participants and reports the unit as a percentage of participants; it does not give a result for that percentage.

In general, a percentage expresses how common an event was in the group being described. It can make an outcome easier to interpret in relation to the group size, but it does not by itself explain why the event occurred. Without a comparison group and a clear account of how the outcome was assessed, a percentage in a treated group is descriptive rather than an estimate of what would have happened under another treatment strategy.

Seroma is the named postoperative event, but the registry record does not provide an operational definition, assessment schedule, or details of who determined whether a seroma had occurred. The endpoint wording connects assessment with hospital discharge and gives a timeframe of up to 50 days; it does not establish that each participant had the same length of observation. The observed primary endpoint value and its precision are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical interpretation depends on how an outcome is defined, which participants contribute data, and how uncertainty is handled. The registry gives a primary outcome title and a population definition, but does not report the primary result or analysis details. The explanations below describe general statistical concepts and distinguish them from what the registry record actually documents.

What does a percentage describe?

For a binary outcome such as whether a participant had a seroma, the observed proportion is the number of participants with the event relative to the number assessed. A percentage is that proportion expressed on a percentage scale. It is a descriptive summary of the observed group. It does not establish that treatment caused the outcome, and it does not account for possible differences between the treated group and another group.

The registry names the outcome as the percentage of participants with postoperative seroma formation, but the observed value and endpoint denominator are not reported. Enrollment of 233 does not establish that all enrolled participants were included in this endpoint analysis. In general, the denominator should match the participants with an evaluable outcome under the analysis definition. If participants are missing, the way they are handled can affect the estimate. Missing-outcome handling is not reported in the registry record.

What would an uncertainty interval tell a reader?

In general, a confidence interval describes a range of values compatible with the observed data under a specified statistical procedure. A narrow interval indicates greater statistical precision than a wide interval, although precision is not the same as freedom from bias. An interval around a single-group percentage would describe uncertainty about that group's event frequency; it would not create a treatment comparison or remove confounding. No confidence interval for the primary outcome is reported in the registry record.

A hypothesis test and its p-value answer a different, narrowly defined question under a chosen null hypothesis and model. A p-value is not the probability that a treatment works or that the null hypothesis is true. It does not measure clinical importance, and it cannot make a non-randomized comparison equivalent to a randomized one. The registry record lists no analyses and reports no primary-outcome p-value.

Why does the design affect an estimate?

Random assignment, when used and properly implemented, can make treatment groups comparable on average with respect to both measured and unmeasured factors. This study is identified as non-interventional. Allocation is not stated, and the registry cautions that arms are not a like-for-like control comparison. General statistical adjustment can address measured differences when suitable data and a prespecified model are available, but it cannot guarantee removal of unmeasured differences. The registry does not report an adjusted analysis or a model specification.

In a single treated group, an event percentage is descriptive. It does not estimate the contrast between outcomes under alternative treatment choices for the same target population. A causal comparison requires an appropriate design and assumptions that support comparison. The registry does not describe a comparator suitable for that purpose.

How should planning calculations be understood?

In general, sample-size calculations use assumptions about the effect to detect, outcome variability, significance level, power, and design. The sample-size assumptions associated with this record describe an illustrative calculation based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two hypothetical arms, and a normal approximation. The assumed effect is a stated fraction of the observed effect. These are planning assumptions, not evidence that the study was designed or conducted that way. The record does not report a protocol sample-size justification.

Participants-per-arm calculations are planning illustrations, not observed power. Observed power is not a substitute for reporting an estimate and its uncertainty: after data are collected, precision is more directly conveyed by the confidence interval around the result. The registry entries do not give the primary endpoint result or the calculation outputs needed to interpret a particular planning illustration. No sample-size value should therefore be inferred from these assumptions alone.

What is not established by the registry?

The record does not describe an interim analysis, a primary-outcome model, covariate adjustment, a confidence-interval method, a missing-data method, or a multiplicity strategy. These details can matter because analysis choices influence estimates and their uncertainty. The absence of a reported method is not evidence that no method was used; it means the method is not reported in the registry record. General statistical explanations should not be mistaken for a description of this study's actual 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("TachoSil®")
n      <- c(228)
events <- c(6)
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  TachoSil®  228  6  2.6  1.0  5.6  1.2  5.6  1.2  5.6

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 13 outcome measures, including the primary seroma outcome and secondary topics such as surgeon ratings, drainage, hospital and ICU stay, and pharmacoeconomic outcomes. Considering many outcomes can increase the chance that at least one result appears notable by chance when multiple statistical tests are performed. In general, a study may address this through a prespecified hierarchy, adjustment procedures, or a clear distinction between confirmatory and exploratory outcomes. A multiplicity strategy is not reported in the registry record.

No analysis records are listed. The record does not state which secondary outcomes were analyzed, whether all were reported, or whether outcome definitions or analysis choices changed. It also does not report p-values or confidence intervals for the primary or secondary outcomes. Thus, multiplicity cannot be evaluated from the posted information, and no inference about statistical significance across outcomes is possible.

The registry defines the intent-to-treat population as participants who received patient information, signed consent, and had TachoSil® applied during lymph node surgery. That wording identifies a population, but the number of participants in it is not stated. The registry enrollment of 233 does not establish the endpoint-specific denominator. The number of participants with missing primary outcome data, the reasons for missingness, and the method used to handle missing data are not reported in the registry record.

In general, missing data can reduce precision and can bias an estimate if participants with missing outcomes differ systematically from those with observed outcomes. The direction and size of any such effect depend on why data are missing and on the analysis method. Without counts and a stated method, readers cannot assess this issue for the primary outcome. The record also does not report whether different analysis populations were used for safety and effectiveness outcomes.

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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: pulmonary embolism (1.3%), post procedural haemorrhage (0.9%), lymphocele (0.9%), groin abscess (0.4%), seroma (0.4%).

For the TachoSil® group, the registry reports 228 participants at risk for serious adverse events and 7 participants affected. For other adverse events, it reports 228 at risk and 25 affected. These are separate registry-reported counts; the record does not clarify whether participants could appear in both categories. Deaths are not reported in the registry record.

The selected serious-event terms and percentages reported are pulmonary embolism, 1.3%; post procedural haemorrhage, 0.9%; lymphocele, 0.9%; groin abscess, 0.4%; seroma, 0.4%; and pleural effusion, 0.4%. These are registry-reported percentages for event terms. The record does not give event-level counts for each listed term, definitions for how terms were selected, or information about possible overlap between terms. The percentages should not be treated as mutually exclusive categories.

In general, an adverse event occurring after treatment does not by itself show that treatment caused it. A control group, fuller clinical context, and consistent event ascertainment can help place safety findings in context. This non-interventional record does not provide a like-for-like control comparison, and the listed figures therefore describe reported events in the TachoSil® group rather than comparative risks attributable to the patch.

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

The record establishes the study's descriptive focus: TachoSil® was used during lymphadenectomy, and postoperative seroma formation was named as the primary outcome. It also identifies an intent-to-treat population, a timeframe of up to 50 days, and a set of secondary outcome topics. These details make the study question and intended observations understandable.

The record does not report the primary outcome result. It therefore cannot tell readers what percentage of participants had postoperative seroma formation, how precisely that percentage was estimated, or how it compares with an alternative. No primary-outcome confidence interval or test is reported. The absence of those results is central: the study aim cannot be treated as a finding.

Even if the single-group outcome result were available, the non-interventional design and absence of a like-for-like comparator would limit causal interpretation. An observed event frequency among participants receiving TachoSil® would describe those participants under the circumstances in which they were treated. It would not, by itself, show what would have happened to the same participants without the patch or under another approach. Other surgical and participant factors could also relate to outcomes.

The serious adverse-event counts and selected event percentages provide some descriptive safety information. They do not demonstrate that the patch caused or prevented any listed event, and the registry does not provide a control comparison for interpreting their frequency. The registry also does not report deaths, missing-data handling, or detailed outcome assessment methods.

In general, a study can be useful for describing clinical experience and identifying outcomes for further investigation without establishing a causal treatment effect. That distinction is especially important when the record does not include a comparator or report the primary outcome estimate. The evidence documented in this record supports a description of the intended study and selected event data, but does not support a conclusion about the magnitude, precision, or causal meaning of the primary outcome.

14. Why This Trial Matters Statistically

This study is statistically relevant because its stated aim is descriptive, while readers may be tempted to interpret a postoperative event percentage as evidence of treatment effect. Separating description from comparison is essential. A frequency observed after TachoSil® use can characterize the recorded group, but causal claims require a design and analysis that support a valid comparison. The registry explicitly identifies the study as non-interventional and cautions that the arms are not a like-for-like control comparison.

The primary endpoint is clinically recognizable as an event outcome, yet the registry's result is not reported. This illustrates why a stated endpoint alone is not enough for statistical interpretation. Readers need the observed estimate, its denominator, and a measure of uncertainty to assess how precisely the outcome frequency is characterized. Those pieces are not reported in the registry record.

The record also lists multiple secondary outcome topics. In general, examining many outcomes raises questions about prespecification and multiplicity, particularly if statistical tests are used to make confirmatory claims. Here, the analysis records and multiplicity approach are not reported, so readers cannot judge whether results were selected or interpreted under a prespecified framework.

Finally, the sample-size assumptions associated with the record are described as planning illustrations based on the observed effect, not as the study's own design rationale. This distinction matters because planning calculations do not replace observed estimates, confidence intervals, or transparent reporting of methods. Nor should a planning calculation be described as observed power. The study underscores the statistical value of complete outcome reporting, clear population denominators, and a design that matches the strength of the intended conclusion.

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 for interpreting effectiveness is that the registry record does not report the primary seroma result. Without the event frequency, endpoint denominator, or a measure of uncertainty, the primary outcome cannot be quantitatively assessed. The record also lists no analysis records, so there are no reported inferential results to interpret.

The study is non-interventional, and the registry does not describe a like-for-like comparator. Allocation is not stated. Consequently, any outcome description would be vulnerable to differences in participants, surgical circumstances, or other factors that may be related to both treatment use and outcome. The registry does not report an adjusted comparison that could address measured differences, and adjustment could not by itself remove unmeasured differences.

The population definition is stated, but the number meeting it and the number contributing to each endpoint are not reported. The registry does not describe loss to follow-up, endpoint-specific missingness, reasons for missing data, or how missing outcomes were handled. Outcome assessment details are also limited: the record does not provide a seroma definition or describe assessment procedures beyond determination at hospital discharge and the stated timeframe of up to 50 days.

Although 13 outcome measures are listed, the registry does not report results for the secondary outcomes or a plan for handling multiple comparisons. It also does not report a protocol sample-size justification, interim analyses, or a detailed statistical analysis plan. Safety information includes selected counts and event percentages, but no comparative safety analysis or deaths are reported. These limits concern what the registry record documents; they do not establish what may or may not have been done outside the record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Use of Tachosil® for Lymph Sealing During Surgery — NCT01920958.
• Registry record last updated 2016-12-19; status last verified 2016-10.
• Results first posted 2016-12-19.
• 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

NCT01920958 is a completed, non-interventional study titled Use of Tachosil® for Lymph Sealing During Surgery. Takeda is the sponsor. Enrollment was 233; the recorded start was 2012-09 and primary completion was 2014-03. The study concerns lymph node resection and describes topical use of a sterile absorbable TachoSil® patch during lymphadenectomy.

The primary outcome is the percentage of participants with postoperative seroma formation over time as determined at hospital discharge, within a timeframe of up to 50 days. The registry defines the intent-to-treat population but does not report the primary outcome result or its statistical precision. Secondary topics include surgeon ratings, drainage, length of stay, and pharmacoeconomic outcomes. No analysis records are listed, and detailed methods for missing data, multiplicity, and outcome analysis are not reported in the registry record.

Serious adverse-event counts and selected event percentages are listed for the TachoSil® group. The non-interventional design and absence of a like-for-like comparator limit causal interpretation of both effectiveness and safety descriptions.