Clinical Trial Comparing Conventional and Robot-assisted(Da Vinci®)Laparoscopic Interventions for Hysterectomy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Clinical Trial Comparing Conventional and Robot-assisted(Da Vinci®)Laparoscopic Interventions for Hysterectomy (NCT00683293), a randomized na study. The primary outcome is Duration of Surgery.

2. Clinical Question

The primary result compares the posted mean duration of surgery in each group. The conventional group had a mean of 75.0 minutes, with a standard deviation of 21.0, among 48 participants. The robot-assisted group had a mean of 106.0 minutes, with a standard deviation of 29.0, among 47 participants. The reported mean difference, expressed as robot-assisted minus conventional, is 31.0 minutes, with a 95% confidence interval from 20.8 to 41.2 minutes and an unadjusted p-value of <0.001.

A secondary endpoint records complications up to 2 weeks. It reports 4 participants in the conventional group and 5 in the robot-assisted group. These results address a different question from operating time, and the small number of recorded complications means that their comparison is less precise. The registry record does not report a cost result, even though costs are included in the study’s stated aim.

3. Trial Design

The registry record describes a randomized, parallel-group trial comparing conventional with robot-assisted laparoscopic hysterectomy. Participants were assigned to one of the two procedures. The record lists enrollment of 100 and status as completed. The primary outcome results include 48 participants in the conventional group and 47 in the robot-assisted group; the registry record does not explain the relationship between the enrollment figure and the outcome-specific group counts.

The trial was unmasked. In a surgical comparison, the procedures themselves are distinct, and the registry record does not describe masking of participants, clinicians, outcome assessors, or analysts beyond the overall masking designation of none. The phase is listed as NA. Kantonsspital Aarau is named as sponsor. The recorded study start is 2008-11, and primary completion is recorded as 2011-09.

The brief summary describes a comparison of operating time, peri-operative outcome, and costs. The posted primary outcome is mean duration of surgery, defined as the time from cut to suture. A secondary outcome is complications, with a timeframe of up to 2 weeks. The record lists complications as a secondary outcome but does not provide a fuller definition of which events qualify or how they were collected. Costs are not reported as an outcome result in the registry record.

The registry record does not report the original sample-size justification, the planned statistical analysis, the allocation procedure in greater detail, or analysis-population definitions. It also does not report details of recruitment, eligibility criteria, missing outcome data, or handling of participants who may have changed or not completed their assigned procedure. These omissions limit how fully the trial’s conduct and analysis can be reconstructed from the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

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 Duration of Surgery, measured over after surgey.

The primary endpoint is duration of surgery, reported as a mean in minutes with a standard deviation for each randomized group. Its description specifies the time from cut to suture. This makes it a continuous measure: each participant contributes a duration, and the group result describes the average duration and the spread of individual durations around that average.

Operating time is relevant to the stated comparison because the trial aims to compare the surgical approaches with respect to the time required to complete surgery. A mean difference expresses the contrast between the two group averages in the original unit, minutes. The reported contrast is robot-assisted minus conventional: 31.0 minutes. The accompanying 95% confidence interval ranges from 20.8 to 41.2 minutes. The registry record labels the timeframe as after surgery, while the outcome description identifies the measured interval as cut to suture.

A mean is useful for describing the typical duration across a group, but it does not describe every participant’s duration. The standard deviations, 21.0 minutes for conventional surgery and 29.0 minutes for robot-assisted surgery, indicate variability within each group. The record does not provide individual observations, medians, or other summaries that would show the shapes of the duration distributions. Nor does it report a fuller operational protocol for timing, such as how start and stop points were recorded. These details matter when interpreting whether the group averages reflect consistently different durations or are influenced by variation among participants.

7. Results Posted in the Registry

• 2 Robot-assisted Laparoscopic Hysterectomy: mean 106.00 versus 75.00 on control; difference 31.00 (95% CI 20.80 to 41.20), standardized effect d = 1.23; z-test p = <0.001.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Complications

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • 2 Robot-assisted Laparoscopic Hysterectomy: 10.6% (5/47) versus 8.3% (4/48) on control; risk difference 2.3 percentage points (95% CI -9.5 to 14.1), risk ratio 1.28 (0.37–4.46); unadjusted two-proportion z-test p = 0.701.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between 2 Robot-assisted Laparoscopic Hysterectomy and the control. The interval gives the range of effects that remain compatible with the data.

The secondary endpoint concerns complications up to 2 weeks. Its posted comparison has a much less precise estimate than the primary surgery-duration comparison: the risk-difference interval extends from -0.095 to 0.141, and the unadjusted p-value is 0.701. The interval includes both directions of difference. This pattern means the complication data do not tightly distinguish among possible group contrasts, unlike the more clearly separated group means for surgery duration.

The two outcomes address different aspects of the procedures. Duration is a continuous measure summarized by group means, while complications are counted as participants with the outcome during a defined follow-up period. A result on one endpoint does not determine the result on the other. The primary comparison’s estimated difference in mean duration does not, by itself, establish a corresponding difference in complication outcomes, costs, or other peri-operative measures.

Unadjusted secondary results generally carry less weight as confirmatory evidence when a trial’s prespecified analysis strategy and approach to multiple comparisons are not reported. When several outcomes or comparisons are considered, the chance of finding an apparently notable result by chance can increase. The registry record does not report a multiplicity plan or a hierarchy for interpreting secondary outcomes. The secondary result should therefore be read as descriptive evidence about the posted outcome, not as a standalone confirmation of a broader conclusion.

The registry record lists one secondary outcome and no reported analyses. It does not report other secondary outcome estimates beyond complications. The record’s adverse-event entries are reported separately and should not be assumed to use the same definitions or ascertainment as the complications endpoint. Costs are mentioned in the study aim, but no cost outcome result is posted. Taken together, the available secondary information is limited and does not provide a comprehensive account of peri-operative outcomes.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Complications

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is continuous because surgery duration is measured in minutes and can take a range of values. The registry record reports a mean and standard deviation for each group. The mean summarizes the group’s average duration; the standard deviation describes how dispersed individual durations are around that average. Neither statistic alone shows the full distribution, including whether there are unusually long procedures or whether durations cluster in distinct groups.

What does the mean difference represent?

The reported mean difference compares the robot-assisted group with the conventional group by subtracting the conventional mean from the robot-assisted mean. The result is 31.0 minutes. Because the estimate is expressed in minutes, it retains the endpoint’s original scale. A positive estimate means the robot-assisted group’s posted mean is higher under this stated direction of comparison. The estimate is a contrast between group averages; it does not say that every robot-assisted procedure took longer than every conventional procedure.

How should the confidence interval be understood?

A confidence interval describes the statistical uncertainty around an estimate under the method used to construct it. For the primary mean difference, the 95% interval extends from 20.8 to 41.2 minutes. It conveys a range of values compatible with the observed summaries and the calculation’s assumptions. It is not a range containing 95% of individual surgery durations, nor does it account automatically for sources of uncertainty that were not measured or included in the calculation. The interval’s position entirely above zero indicates that the estimated contrast is positive across the interval.

What does the p-value add?

The unadjusted p-value is <0.001 for the primary comparison. A p-value describes how unusual a result at least as discrepant as the observed result would be under a specified null model, assuming the calculation’s conditions hold. It is not the probability that the null hypothesis is true, and it does not measure the size or practical importance of a difference. It also does not remedy limitations in the trial design, outcome measurement, or reporting. The registry record does not report a fuller statistical plan for the primary analysis.

How is the complication comparison different?

Complications are a binary outcome at the participant level: a participant is counted as having or not having the recorded outcome during the stated timeframe. The posted counts are 4 of 48 participants in the conventional group and 5 of 47 in the robot-assisted group. The reported risk difference is 0.023, with a 95% interval from -0.095 to 0.141. This interval crosses zero and includes both possible directions of difference. Its width reflects substantial uncertainty in the comparison. The unadjusted p-value is 0.701; that value does not establish equivalence or rule out a potentially meaningful difference.

The registry record also includes a risk ratio and an odds ratio for complications. These are alternative ways of expressing a contrast between group risks. A risk ratio compares the risks as a ratio, while an odds ratio compares the odds. Such relative measures can be difficult to interpret without the underlying event counts and an appreciation of their uncertainty. For this comparison the interval for the risk ratio is 0.365 to 4.464, and the interval for the odds ratio is 0.329 to 5.211. Both are wide, which is consistent with limited precision when the event counts are small.

Why does dispersion matter?

For a continuous endpoint, variation within groups affects how precisely a group difference can be estimated. Larger variation generally makes it harder to distinguish a group contrast from the scatter of individual observations, all else equal. The reported standard deviations are 21.0 minutes in the conventional group and 29.0 minutes in the robot-assisted group. The registry record does not describe whether the analysis checked the distributional assumptions behind the mean comparison or used a method tailored to any unusual distributional features.

For a binary endpoint, the amount of information depends strongly on how many participants experience the event. With few events, moving a small number of participants between outcome categories can substantially affect the estimated contrast. That is why a non-significant result for complications should not be read as proof that the two approaches have the same complication risk. Over-dispersion is a general concern when observed variability exceeds what a model assumes; the registry record does not report whether over-dispersion was assessed or relevant to the analyses.

The comparisons are described as unadjusted. An adjusted analysis could account for prespecified participant or procedural factors, if such factors were measured and included in a suitable model. The registry record does not report adjusted analyses, covariate choices, or model diagnostics. The displayed estimates therefore provide unadjusted comparisons based on the posted summaries, not evidence about adjusted effects.

The registry record lists no reported analyses, and it does not give a statistical analysis plan. Consequently, it is not possible to establish from the registry record whether the analyses were prespecified, how missing observations were handled, which participants were included in each analysis, or whether additional analyses were conducted but not posted. The statistical results can be described as recorded, while these gaps should remain part of their interpretation.

11. Confidence Intervals and Precision

The primary estimate is a mean difference of 31.0 minutes, with a 95% confidence interval from 20.8 to 41.2 minutes. The interval gives a sense of the precision of the estimated average contrast: the values it spans are narrower than the full range of possible differences, but they still allow for variation in the size of the contrast. Every value in this interval is positive. The interval is about the mean difference, not about where individual participants’ surgery durations fall.

The standard deviations add information about within-group variation: 21.0 minutes for conventional surgery and 29.0 minutes for robot-assisted surgery. These are not confidence intervals. They describe spread among observed durations rather than uncertainty in the estimated group means. The group sizes for this outcome are 48 and 47, and the registry record does not report a distributional assessment or adjusted model that could add context to the estimate’s precision.

Precision is more limited for complications. The risk-difference interval runs from -0.095 to 0.141 and includes zero, as well as values in either direction. The event counts are 4 and 5. The interval’s breadth means that the posted data do not pinpoint the size or direction of a complication difference. The risk-ratio interval, 0.365 to 4.464, and odds-ratio interval, 0.329 to 5.211, also span a broad range of possible contrasts.

Confidence intervals quantify sampling uncertainty under the calculation used; they do not incorporate every possible source of uncertainty. They cannot resolve uncertainty about outcome definitions, missing data, analysis choices, or generalizability when those details are not reported. A narrow or wide interval should therefore be interpreted alongside the design and reporting information, not as a complete assessment of evidence quality.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are participants per arm for the continuous and binary outcomes in this trial; they are not total event counts. The listed planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is set as the stated fraction of the observed effect. For a time-to-event calculation, figures would instead represent total events, but no time-to-event outcome is listed for this trial.

The 80% power column gives the planned number of participants per arm for a design with an 80% chance of detecting the specified effect if that effect were the true one, under the planning assumptions. The 90% power column represents a design with a higher chance of detecting that specified effect under those same assumptions. These are planning illustrations based on the observed effect, not observed power from the completed trial.

The rows use 100%, 75%, and 50% of the observed effect as planning targets. A smaller target effect is harder to distinguish from random variation, so the planning figures rise as the target effect becomes smaller. For the primary continuous endpoint, the listed participants per arm for 80% power are 11, 19, and 42 across those effect targets; for 90% power they are 14, 25, and 56. For complications, the corresponding 80% figures are 2,536, 4,386, and 9,591, and the 90% figures are 3,395, 5,871, and 12,839.

These calculations do not establish what sample size the investigators originally planned or what assumptions informed the trial design. The original design assumptions and sample-size justification are not reported in the registry record. The planning figures are illustrative calculations based on observed effects and should not be interpreted as a reconstruction of the trial’s original design.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 31.000; pooled standard deviation σ = 25.275.
2. n = 2 × (1.96 + 0.842)² × 25.275² / 31.000² = 10.4, rounded up to 11 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 31                      # observed difference in means
sigma <- 25.2754715557513                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(683293)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 11 (80% power), 14 (90% power)
 75% of observed effect: n per arm = 19 (80% power), 25 (90% power)
 50% of observed effect: n per arm = 42 (80% power), 56 (90% power)
power.t.test: 11.5 
Simulated power at n = 11 per arm: 0.778 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry record does not report how the investigators planned to handle multiplicity across outcomes or analyses. A multiplicity plan specifies how conclusions are controlled or prioritized when several statistical comparisons are made. Without such a plan, it is not possible to tell whether the primary endpoint was treated as the sole confirmatory outcome, whether secondary outcomes were intended as exploratory, or whether any adjustment was planned for multiple testing. The unadjusted p-values should therefore be interpreted as results for their individual comparisons, not as evidence that a trial-wide error rate was controlled.

The registry record lists no reported analyses. It includes posted outcome summaries and unadjusted comparison statistics, but it does not provide the complete statistical analysis plan, analysis code, model specifications, or details about whether the reported analyses were prespecified. The record does not report interim analyses or stopping rules. Their presence or absence cannot be inferred from the completed status alone.

Handling of missing data is also not reported in the registry record. The outcome-specific group counts are 48 for conventional surgery and 47 for robot-assisted surgery, while enrollment is listed as 100. The record does not explain why the outcome counts differ from the enrollment figure, whether any measurements were missing, or how participants without an outcome measurement were treated. It also does not state whether the analysis followed an intention-to-treat, per-protocol, or other population definition.

Other details that would help assess the comparison are not reported in the registry record, including eligibility criteria, the allocation sequence method, concealment procedures, outcome-assessment procedures, and treatment of deviations from assigned procedures. The overall masking designation is none, but the record does not separately describe who knew assignments at each stage or whether any assessment procedures were standardized.

These reporting gaps do not alter the arithmetic of the posted summaries, but they limit evaluation of bias, prespecification, and the scope of the inferences. The results are best understood as the comparisons attached to the available registry outcomes, with uncertainty about the analysis and data-handling details left explicit.

15. 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.

The registry record lists zero participants with serious adverse events among 48 participants in the conventional group and zero among 47 participants in the robot-assisted group. It also lists zero participants with other adverse events in each group, using the same group counts. These entries report what was recorded in those categories; they do not establish that no adverse events of any kind occurred during the trial.

The registry record does not define the serious and other adverse-event categories, describe how events were collected, or report whether the categories include all events or only events meeting particular criteria. It also does not provide event terms in the serious-event listing. Therefore, the zero counts should be read narrowly as registry entries for those categories, rather than as a complete safety profile.

These adverse-event figures are separate from the complications endpoint, which reports 4 participants in the conventional group and 5 in the robot-assisted group. The registry record does not explain the relationship between the outcome definitions. The complication counts and adverse-event entries should not be combined or treated as interchangeable without definitions that clarify their overlap.

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

The posted data indicate that the robot-assisted group had a higher mean surgery duration than the conventional group. The estimated difference is 31.0 minutes, with a 95% confidence interval from 20.8 to 41.2 minutes and an unadjusted p-value of <0.001. This is evidence about the recorded mean duration comparison; it does not establish that the procedure caused the difference independently of all other factors, because adjusted analyses and relevant design details are not reported in the registry record.

The complication comparison is less conclusive. The posted counts are 4 and 5 participants, and the risk-difference interval spans zero and values in both directions. Its unadjusted p-value is 0.701. This does not demonstrate that the approaches have equal complication outcomes, nor does it establish a difference. The available event counts yield limited precision for distinguishing among possible contrasts.

Neither result answers the trial’s cost question. The study aim mentions costs, but cost results are not reported in the registry record. The record also does not report a detailed definition of complications, handling of missing data, an analysis-population definition, or a multiplicity plan. These omissions constrain interpretation beyond the statistics attached to the posted outcomes.

The results do not show how surgery duration or complications vary across participant subgroups, and the registry record does not provide enough information to assess such patterns. The findings also cannot be extended automatically to other surgical settings or populations. They describe the randomized groups and outcomes as recorded in this trial; generalizability depends on details of participants, procedures, and clinical settings that are not fully reported.

In short, the clearest posted statistical contrast concerns mean surgery duration. The complication estimate remains imprecise, and safety entries and costs are incompletely characterized. Statistical evidence about these outcomes should be kept distinct from broader judgments about the procedures, which require information beyond the registry results.

17. Why This Trial Matters Statistically

This trial illustrates why outcome type matters when reading clinical results. Surgery duration is continuous and summarized by means, standard deviations, a mean difference, and a confidence interval. Complications are a participant-level binary outcome, summarized by event counts and comparative measures such as a risk difference. Each measure answers a different question and carries different uncertainty.

The contrast in precision is also instructive. The primary mean difference has a confidence interval entirely above zero, whereas the complication risk-difference interval spans zero and extends in both directions. A non-significant p-value for a secondary endpoint is not a demonstration of no difference, especially when the event counts are small and the interval is broad. Interpreting the estimate and its interval together is more informative than treating a p-value as a verdict.

The record also shows the importance of distinguishing an observed result from a planning illustration. The sample-size figures are based on the observed effect and stated calculation assumptions; they do not reveal the original design rationale. In particular, a planning calculation based on a completed trial’s observed effect is not evidence that the trial had a corresponding probability of success.

Finally, registry reporting determines what can be assessed. Missing information about the statistical plan, analysis populations, missing data, multiplicity, and outcome definitions limits the strength and breadth of conclusions. Clear reporting of these details would help readers judge whether analyses followed prespecified methods and how much confidence to place in results beyond the posted summaries.

18. 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.

Several limitations specific to this trial follow from the registry record. The primary outcome timeframe is labeled after surgery, while its description defines duration from cut to suture. The record does not give a more detailed account of how the timing interval was operationalized or measured. This leaves some uncertainty about outcome measurement, despite the stated description.

The primary outcome population field is blank, and the registry record does not report eligibility criteria or a detailed description of participants. It lists enrollment of 100, while outcome-specific group counts are 48 and 47. The record does not explain whether the difference reflects missing outcomes, exclusions, or another reason. Consequently, the extent to which the outcome results include all randomized participants cannot be determined from the registry record.

The trial was unmasked, and the record does not report separate masking or assessment procedures. It also does not provide details about allocation sequence generation or concealment. For a procedure comparison, unreported differences in experience, learning, or implementation could be relevant to interpreting operating time; the registry record does not provide information to evaluate those factors. This is a consideration, not a claim that any particular difference occurred.

The primary outcome is reported with group means and standard deviations, but no distributional summaries or adjusted analysis are reported. For complications, the event counts are limited and the confidence interval is broad. The complication definition is not described in detail, and the relation between that endpoint and the separate adverse-event categories is not explained.

Finally, costs are part of the stated aim but no cost results are reported. The registry record does not include the original sample-size justification, full statistical analysis plan, multiplicity approach, missing-data methods, or analysis-population definition. These gaps restrict assessment of the planned analyses and of how broadly the posted findings should be interpreted.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Clinical Trial Comparing Conventional and Robot-assisted(Da Vinci®)Laparoscopic Interventions for Hysterectomy — NCT00683293.
• Registry record last updated 2014-04-16; status last verified 2014-03.
• Results first posted 2014-04-16.
• 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.

22. Record Summary

NCT00683293 is a completed, randomized, parallel-group trial sponsored by Kantonsspital Aarau. It compares conventional laparoscopic hysterectomy with robot-assisted Da Vinci® laparoscopic hysterectomy. The registry record lists enrollment of 100, no masking, and phase NA.

The primary endpoint is mean duration of surgery from cut to suture. The conventional group mean is 75.0 minutes and the robot-assisted group mean is 106.0 minutes. The reported mean difference is 31.0 minutes, with a 95% confidence interval from 20.8 to 41.2 minutes and an unadjusted p-value of <0.001.

The secondary complications outcome covers up to 2 weeks and reports 4 participants in the conventional group and 5 in the robot-assisted group. The registry record does not report the trial’s original sample-size justification, detailed analysis plan, missing-data handling, or cost results.