This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Surgical Trial Comparing LIGASURE Assisted Recto-Sigmoid Resection and Omentectomy Compared to Stand (NCT01549925), a randomized na study. The primary outcome is Surgical Time.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01549925 |
| Phase | NA |
| Condition | Epithelial Ovarian Cancer |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 50 |
| Arms in the primary outcome | 2 |
| Lead sponsor | University of Utah |
| Results posted | Yes |
2. Clinical Question
Population
Women with stage IIIC or stage IVA epithelial ovarian cancer were the population named in the official title. The broader condition listed in the registry record is epithelial ovarian cancer. Other eligibility details and the characteristics of participants enrolled are not reported in the registry record.
Intervention
The intervention was resection using the FDA-approved LIGASURE device during omentectomy and recto-sigmoid resection. The objective was to evaluate its use during omentectomy and/or recto-sigmoid resection. The record does not explain which specific procedures were performed for each participant.
Comparator
The comparison was standard surgical resection using clamps and surgical ligatures. The trial was randomized and used a parallel design, with 25 participants reported in each arm.
Primary question
The primary question was whether use of LIGASURE would reduce surgical time compared with standard surgical resection. Surgical time was reported as a mean in seconds, with a 95% confidence interval for each arm. The registry record does not report a statistical test or an estimate of the between-arm effect.
3. Trial Design
This was a prospective randomized surgical trial with a parallel-group design and no masking. The record lists an enrollment of 50. The posted outcome data include 25 participants for standard surgical resection and 25 for LIGASURE. Equal numbers in the posted arm results do not, by themselves, establish further details about how randomization was generated or concealed; those details are not reported in the registry record.
The trial compared standard surgical resection using clamps and surgical ligatures with resection using the LIGASURE device during omentectomy and resection of the recto-sigmoid portion of the colon. The objective also describes use during omentectomy and/or recto-sigmoid resection. How those procedures were selected or applied to individual participants is not reported in the registry record.
The listed sponsor was the University of Utah. The record gives a start date of 2011-01 and a primary completion date of 2014-09, and its status is completed. The phase is listed as NA. The registry record does not report further details about the surgical setting, participant flow, baseline characteristics, protocol deviations, or the method used to carry out randomization.
Randomization is intended to support a fair comparison by assigning participants to treatment groups through chance rather than clinical choice. In a parallel design, participants are assigned to one group for the comparison rather than receiving both approaches in sequence. These are general features of trial design; they do not establish that the groups were balanced on every relevant characteristic or that the trial's analysis preserved the benefits of randomization.
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
| Stage | Standard Surgical Resection | LIGASURE |
|---|---|---|
| STARTED | 25 | 25 |
| COMPLETED | 25 | 25 |
| NOT COMPLETED | 0 | 0 |
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.
| Characteristic | Unit | Standard Surgical Resection | LIGASURE | Total |
|---|---|---|---|---|
| Participants analysed | 25 | 25 | 50 | |
| Age, Customized: < 50 years | Participants | 1 | 7 | 8 |
| Age, Customized: 50-70 years | Participants | 16 | 13 | 29 |
| Age, Customized: >70 years | Participants | 8 | 5 | 13 |
| Sex: Female, Male: Female | Participants | 25 | 25 | 50 |
| Sex: Female, Male: Male | Participants | 0 | 0 | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Surgical Time, measured over at time of surgery, up to 10 minutes.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | 95% Confidence Interval |
| Unit | SECONDS |
| Endpoint classification | Continuous Endpoint |
The primary endpoint was surgical time, recorded in seconds and summarized as a mean for each arm. The record describes the timeframe as “at time of surgery, up to 10 minutes.” Its objective was to assess whether LIGASURE use during omentectomy and/or recto-sigmoid resection would reduce surgical time compared with standard resection using clamps and surgical ligatures. The exact operational definition of the timed interval, including its start and stop points, is not reported in the registry record.
Surgical time is a continuous measure: it can take values along a scale rather than being limited to categories. A mean provides a summary of the recorded times in an arm. It can be useful for describing an average difference in operating time, but it does not show how widely individual participants' times varied. The registry record reports confidence intervals for the arm means, but does not report a measure of within-arm spread such as a standard deviation.
Time is used because it directly reflects the stated objective of comparing the duration of the surgical work. It is a procedural outcome, not a measure of cancer control, recovery, or another clinical outcome. Whether a difference in this timing measure corresponds to a patient-important outcome is not assessed by the endpoint description. The record reports no secondary outcomes.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted mean surgical time was 417.0 seconds in the standard surgical resection arm, with a 95% confidence interval from 378.0 to 455.0 seconds. In the LIGASURE arm, the posted mean was 338.0 seconds, with a 95% confidence interval from 296.0 to 379.0 seconds. These are descriptive arm-level results. They show that the reported mean was lower in the LIGASURE arm, but they do not by themselves provide a formal estimate or test of the difference between groups.
A confidence interval expresses uncertainty around an estimate under the assumptions of the method used to construct it. In general, a 95% confidence interval is a procedure that would cover the underlying quantity in 95% of repeated samples when its assumptions hold. It is not a guarantee that the particular interval contains the true value, nor does it directly state the probability that the true value lies within these particular bounds. The registry labels the reported intervals as 95% confidence intervals, but does not describe how they were calculated.
The intervals are reported separately for the two arm means. They are not a confidence interval for the contrast between arms. To evaluate the primary comparison statistically, readers would need an estimate of the between-arm effect and its uncertainty, along with an appropriate analysis. Those results are not reported in the registry record. The record lists no analyses, and the posted results do not include a p-value or an adjusted estimate. Consequently, the arm means alone do not establish whether the observed difference is compatible with chance variation under a specified statistical model.
The point estimates should also be read in light of the reported sample sizes: 25 participants in each arm. The trial enrolled 50 participants overall. The registry record does not give participant-level times, a distributional summary, or details of missing outcome measurements. It is therefore not possible from these results to assess the shape of the time distribution, the influence of unusually long or short procedures, or whether all randomized participants contributed to the endpoint.
The registry record identifies this as a randomized comparison, which is relevant to how a treatment contrast might be interpreted. However, the record does not report the randomization method, analysis population, or handling of protocol deviations. No inferential conclusion about the comparative effect should be substituted for the unreported analysis. The posted numbers describe the means and their intervals; they do not establish that either surgical approach is superior, nor do they establish equivalence.
9. Statistical Methods Explained
The primary outcome is a continuous variable, and the registry reports an arm-specific mean with a 95% confidence interval for each treatment group. A mean is a measure of the center of a set of observations. It compresses the participant-level data into a single value, so it cannot show whether times were tightly grouped or widely dispersed. The record does not report a standard deviation, median, range, or individual observations.
What do the confidence intervals describe?
In general, a confidence interval describes the precision of an estimate under a statistical procedure and its assumptions. A narrower interval indicates greater precision for that estimate, while a wider interval indicates more uncertainty. The posted intervals are 378.0 to 455.0 seconds for standard surgical resection and 296.0 to 379.0 seconds for LIGASURE. These intervals describe uncertainty around each arm's mean, not directly around the difference between the arm means.
A comparison requires an effect measure that relates the two arms, such as a difference in means, together with uncertainty for that contrast. Such a result is not reported in the registry record. Separate confidence intervals should not be treated as a substitute for a confidence interval or test for the comparison. The record also does not state the interval-construction method, whether the analysis adjusted for any covariates, or which assumptions were checked.
Why does the analysis model matter?
General statistical reasoning: a model for a continuous outcome should reflect the way the observations vary and how the trial was conducted. If the distribution of surgical times is strongly asymmetric or includes influential extreme values, a simple comparison of means can be sensitive to those features. If variability differs between groups, a method that assumes equal variability may not represent the data well. The posted results do not include the information needed to assess these issues, and the registry record does not describe a statistical model for the primary comparison.
Randomization supports a comparison between assigned groups, but it does not remove the need to specify how outcomes are analyzed. For example, an analysis may compare participants according to their assigned arm, or may use a different population or adjustment approach. The registry record does not report the analysis population or the method used to account for any departures from assignment. It also does not report how missing surgical-time values, if any, were handled.
What can the posted summaries establish?
The arm-specific means and intervals describe the posted continuous outcome. The mean is 417.0 seconds for standard surgical resection and 338.0 seconds for LIGASURE. The confidence intervals communicate uncertainty about each mean under an unspecified calculation method. They do not establish a causal effect or statistical significance without a reported between-arm analysis. The record lists no analyses, so there is no sponsor-reported comparative result to interpret.
The registry record identifies a sample size of 25 in each arm for the posted outcome. That describes the data counts shown for the two groups; it is distinct from a prospective sample-size justification. The record does not report a sample-size calculation or its assumptions. The general planning illustration described in the record is not the trial's own design justification, and no numerical planning results are reported in the registry record. Planning illustrations are hypothetical calculations, not observed power and not evidence that the trial had a particular probability of detecting an effect.
What does absence of a test result mean?
When an outcome is reported only with group summaries, a reader can describe those summaries but cannot recover every element of the trial analysis. A p-value, if reported, would address compatibility between data and a specified null model; it would not measure the size or clinical importance of an effect. A confidence interval for the contrast would help show the range of effects reasonably compatible with the data and analysis assumptions. Neither is reported for the comparison in this registry record. General explanation of these methods does not fill in the missing analysis results.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists one outcome measure and no secondary outcomes. It also lists no analyses. This means that no multiplicity-adjustment strategy or set of additional outcome analyses is reported in the record. The record does not state whether there were interim analyses, whether the primary outcome was changed, or whether other analyses were planned but not posted. These details are not reported in the registry record.
Multiplicity is a general concern when several outcomes, time points, subgroups, or statistical tests are examined. Repeated testing can increase the chance of obtaining a seemingly notable result by chance, so an analysis plan may specify how such testing will be handled. With no comparative analysis reported and no secondary outcomes listed, the registry record does not permit assessment of any multiplicity procedure or of whether unlisted analyses were conducted.
The posted arm counts are 25 for standard surgical resection and 25 for LIGASURE. The record does not describe whether all enrolled or randomized participants were included in the analysis, or whether every participant had an evaluable surgical-time result. Missing outcome data, exclusions, withdrawals, and protocol deviations are not reported in the registry record. Nor is it reported whether the analysis followed randomized assignment or used another population.
These omissions matter because estimates can depend on which participants contribute data and how missing observations are handled. General statistical practice distinguishes the population defined by randomization from the subset with observed outcomes, and prespecifies how incomplete data will be addressed. The registry record does not provide enough information to determine which approach was used. No missing-data method should be inferred from the arm summaries alone.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Standard Surgical Resection | 0 | 25 | 0.0% |
| LIGASURE | 0 | 25 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Standard Surgical Resection | 0 of 25 |
| LIGASURE | 0 of 25 |
For serious adverse events, the registry reports 0 affected participants among 25 at risk in the standard surgical resection arm and 0 among 25 at risk in the LIGASURE arm. For other adverse events, it likewise reports 0 affected participants among 25 at risk in each arm. These are the posted counts; they do not describe the nature, severity, timing, or duration of events beyond the categories shown.
The deaths field has no reported value for either arm. Death counts are therefore not reported in the registry record; a missing value should not be read as a count of zero. No serious adverse-event terms are listed.
General interpretation: zero events recorded in a trial does not establish that an event cannot occur, or that the approaches have identical safety. A safety count depends on the number of participants observed, the duration and completeness of follow-up, and how events were defined and collected. Follow-up details and adverse-event collection methods are not reported in the registry record. These figures should be read as the recorded counts for this trial, not as a guarantee about safety in other settings or populations.
12. What the Result Does, and Does Not, Mean
The registry record presents arm-specific means for the primary surgical-time outcome: 417.0 seconds with standard surgical resection and 338.0 seconds with LIGASURE. It also presents a 95% confidence interval for each mean. The results therefore provide descriptive information about the average reported time in each arm and the uncertainty intervals attached to those means.
The record does not report a formal comparison between arms. It gives no estimated between-arm effect, confidence interval for that effect, or p-value. The apparent ordering of the two reported means is not, by itself, evidence that the approaches differ statistically. Nor does the absence of an analysis establish that there was no difference. The posted data are insufficient to determine the precision of a comparative effect or whether it is compatible with a range of values.
The endpoint concerns surgical time. It does not directly measure other outcomes such as cancer control, recovery, quality of life, or longer-term complications. The registry record lists no secondary outcomes, so it does not provide results for those questions. The safety counts show no affected participants in the posted adverse-event categories, but the record does not provide enough follow-up or collection detail to treat those counts as comprehensive evidence of risk.
This trial record also does not report the analysis population, missing-data approach, or protocol details needed to fully evaluate the analysis. The randomized design is an important feature, but interpretation of a treatment comparison depends on how outcomes were analyzed and reported. Accordingly, the posted results support a description of the arm means and intervals, not a conclusion that LIGASURE does or does not reduce surgical time, or that the methods are equivalent.
13. Why This Trial Matters Statistically
This trial illustrates an important distinction in clinical statistics: arm-level descriptive results are not the same as a statistical comparison. The registry reports a mean and confidence interval for each group, which helps describe surgical time within the groups. The primary question, however, concerns a contrast between approaches. A direct estimate of that contrast and its uncertainty would be needed to answer the comparative question statistically.
The example also shows why the outcome's definition and analysis plan matter. Surgical time is continuous, and the meaning of a measured time depends on precisely which interval was timed and how observations were summarized. The record gives the endpoint label, unit, and timeframe, but does not report the operational start and stop points or the method used to construct the confidence intervals. Without those details, readers have limited ability to assess reproducibility and assumptions.
Randomized allocation and a parallel design provide a framework for a comparative trial, but a registry record still needs transparent reporting of the analysis population, missing data, and between-arm results. Those items are not reported. Their absence does not change the descriptive values, but it limits the conclusions that can be drawn from them.
The posted adverse-event counts offer another statistical lesson: zero recorded events are counts, not proof of no risk. The size and follow-up of a study, as well as how events were collected, shape what such results can tell readers. Together, these features make the record useful for understanding the difference between reporting outcome summaries and reporting a complete inferential analysis.
14. 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 comparative analysis of the primary outcome. Although it gives the mean and 95% confidence interval for each arm, it does not give an estimate or interval for the between-arm effect, a test result, or a detailed statistical method. This is the central limitation for interpreting the trial's stated objective.
Details needed to assess the endpoint are also limited. The record identifies surgical time in seconds and gives the timeframe as at time of surgery, up to 10 minutes, but does not define the exact start and stop points for timing. It does not explain which procedures each participant underwent, despite describing omentectomy and recto-sigmoid resection in the intervention and objective.
The registry record does not report baseline characteristics, the randomization procedure, allocation concealment, or the analysis population. It does not state whether outcome data were missing, how missing data were handled, or whether participants deviated from assigned procedures. These omissions limit assessment of the comparability of groups and the completeness of the endpoint results.
The safety reporting is also limited: event counts are posted, but follow-up duration, event definitions, ascertainment methods, and death counts are not reported. No secondary outcomes are listed. The record does not report a sample-size justification, interim-analysis plan, or detailed statistical plan. These details cannot be inferred from the posted summaries.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Surgical Trial Comparing LIGASURE Assisted Recto-Sigmoid Resection and Omentectomy Compared to Stand — NCT01549925.
- Registry record last updated 2016-01-28; status last verified 2015-12.
- Results first posted 2016-01-28.
- 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.
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18. Record Summary
The registry record describes a completed, randomized, parallel-group surgical trial sponsored by the University of Utah. It lists an enrollment of 50 and compares standard surgical resection using clamps and surgical ligatures with LIGASURE-assisted resection. The condition is epithelial ovarian cancer; the official title specifies women with stage IIIC or stage IVA disease. The record gives a start date of 2011-01 and a primary completion date of 2014-09.
The primary outcome is mean surgical time in seconds, with a 95% confidence interval reported for each arm. The posted means are 417.0 seconds for standard surgical resection and 338.0 seconds for LIGASURE, with 25 participants listed in each arm. No comparative analysis or secondary outcome results are reported. The record reports zero serious and other adverse events in each arm, while deaths are not reported.