Harmonic Scalpel Vs. Electrocautery in Breast Reduction Surgery: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Harmonic Scalpel Vs. Electrocautery in Breast Reduction Surgery (NCT00819260), a randomized na study. The primary outcome is Time for Operation.

2. Clinical Question

The clinical question is therefore about a procedural comparison and its measured operative time, rather than a broad assessment of all aspects of breast reduction. The registry lists three intended metrics in its summary: time to complete the operation, drainage volume in the days immediately following surgery, and patient pain during those days. It identifies hematoma among the secondary outcomes as well.

Although the registry describes a randomized trial with a parallel model, its arm descriptions refer to the device used on a particular breast side. The record does not explain how side assignment was randomized, whether every participant received both devices, or whether a within-participant comparison was planned. Those details matter because observations from two breasts in the same participant may be related. The posted summaries alone do not establish the comparison structure or the analysis needed to account for it.

3. Trial Design

The registry identifies this as a randomized, single-masked, parallel-model clinical trial comparing the Harmonic Scalpel with electrocautery in breast reduction surgery. The sponsor is Dartmouth-Hitchcock Medical Center. The record lists enrollment of 31 and gives the condition as hyperplasia. The phase is recorded as not applicable.

The study started in 2009-03, and primary completion is recorded as 2010-01. Its status is terminated. The registry record does not state why the trial was terminated, whether the planned recruitment was completed, or whether termination affected the collection or analysis of outcomes. The listed enrollment should not automatically be treated as the number analyzed for every measure: the operation-time summaries each have n=31, while the analysis population and outcome-specific completeness are not described in detail.

The two device groups are described by the side on which the breast was reduced. In one group the Harmonic Scalpel was used on that side; in the other, electrocautery, identified as current practice, was used. The registry nevertheless labels the overall model parallel. It does not clarify whether each participant was assigned to one device, whether participants received different devices on opposite sides, or how any such paired observations were handled statistically. The unit of randomization and the identity of the masked party are not reported in the registry record.

The primary outcome is time to complete breast reduction per breast, in minutes, on the day of surgery. The registry lists volume of drainage in surgical drains, pain level in surgical sites, and hematoma among the secondary outcomes. It records four outcome measures, but does not give results for the secondary outcomes. It records no analyses. No detailed protocol, allocation procedure, masking procedure, eligibility criteria beyond the stated primary-outcome population, or sample-size justification is reported 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: Forty-three women were identified as potential study participants from May to December 2009. Three were excluded, because two were unable to consent and one was under 18 years old. Nine women declined to participate. Of the remaining 31 patients (72.1% of those identified), all completed the informed consent, the surgery, and the follow-up process.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Women over the age of 18 who are not pregnant with symptomatic breast hypertrophy who underwent breast reduction 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.

6. Primary Endpoint

The registry lists the primary outcome as Time for Operation, measured over day of surgery.

The primary endpoint is the time required to complete breast reduction per breast, measured in minutes on the day of surgery. It directly measures operating duration for the surgical task under comparison. The registry’s study summary says the trial aimed to assess time taken to complete the operation alongside drainage volume and patient pain after surgery. Operative time is thus a procedural outcome, not a direct measure of later recovery or patient experience.

The registry identifies the endpoint’s summary parameter as a median and lists standard deviation as its measure of dispersion. The posted values are 32.9 minutes with standard deviation 14.7 for the Harmonic Scalpel group, and 31.0 minutes with standard deviation 8.1 for the electrocautery group. Each group is listed with n=31. These are summaries of the recorded operation-time data; they do not, by themselves, establish whether a difference between devices is statistically distinguishable from chance or clinically meaningful.

In general, operative time can help describe how a procedure is performed and how its duration varies among observed cases. It is useful to distinguish the typical time from the spread of times, and to consider whether a reported summary matches the underlying data distribution. Here, the registry labels the central summary as a median but reports standard deviations. Because no individual observations, confidence intervals, test results, or explanation of that combination are reported in the registry record, the precision and statistical uncertainty of the endpoint cannot be fully assessed from these summaries alone.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Randomization is intended to reduce systematic differences between comparison groups by assigning the intervention according to a chance process. In general, randomization supports a causal comparison when allocation is implemented as planned, outcomes are collected consistently, and the analysis respects the design. The registry identifies this study as randomized but does not describe sequence generation, concealment of allocation, or the unit assigned. Those methods are not reported in the registry record, so the label alone does not reveal how randomization was carried out.

What does the design label establish?

The record describes a single-masked, parallel-model trial. “Single-masked” indicates that some party was masked, but the record does not say whether that party was a participant, clinician, outcome assessor, or another person. The parallel-model label ordinarily describes groups followed under separate assigned interventions. However, the arm descriptions specify use of a device on a breast side. The record does not explain whether participants had one device or both, or how side allocation was connected to the parallel designation. This is not a minor reporting detail: if both sides of a participant contributed data, those side-specific measurements could be correlated.

In general, paired data are analyzed by accounting for the within-person relationship, while independent-group methods assume observations in one group do not depend on observations in the other. A paired analysis can be more precise when the within-person relationship is used appropriately. Treating related observations as independent can misstate uncertainty. The registry does not report the analysis method, so it is not possible to determine how this issue was addressed.

How should the outcome summaries be read?

The primary measure is operation time per breast, in minutes, on the day of surgery. The registry labels its summary parameter as a median and its dispersion as standard deviation. In general, the median is the central ordered observation, whereas standard deviation describes variability around the mean. These statistics can appear together, but the registry does not explain why this combination was selected or how the summaries were calculated. The posted values are 32.9 with standard deviation 14.7 for the Harmonic Scalpel group and 31.0 with standard deviation 8.1 for the electrocautery group, with n=31 in each. No confidence interval or direct between-group estimate is reported.

A confidence interval is a range constructed by a statistical method to express uncertainty around an estimate. It can communicate both the direction and precision of a comparison. The registry does not report one for operation time, and it gives no test statistic or p-value. Without an estimated contrast and its uncertainty, readers cannot determine how compatible the observed group summaries are with a range of possible underlying effects. A difference between group summaries is descriptive; it is not itself a test of statistical evidence.

Why does the analysis population matter?

In general, an analysis should make clear who was included, how missing outcomes were handled, and whether participants were analyzed according to their randomized assignments. These choices can affect the interpretation of a randomized comparison. The registry lists enrollment of 31 and n=31 in each operation-time group, but does not define the analysis population or state whether all randomized participants contributed data. It does not report missing outcome counts or any imputation approach. The matching group counts therefore do not answer every question about completeness or analysis conduct.

The registry records no analyses. It does not state whether an analysis plan was prespecified, whether adjusted or unadjusted methods were used, or how the reported summaries relate to a planned primary analysis. No sample-size justification or target power is reported in the registry record. General sample-size calculations can illustrate the amount of information needed to detect a chosen effect under stated assumptions; they are planning exercises, not evidence that a completed trial had a particular probability of finding a result. No such trial-specific justification should be inferred from the posted summaries.

What is the role of dispersion?

Dispersion describes how far observations tend to spread around a center. It matters because groups with similar central summaries can have quite different variability, and greater variability generally makes estimates less precise when other design features are comparable. Standard deviations of 14.7 and 8.1 are reported for the two operation-time groups. These values describe spread under the registry’s chosen reporting convention, but the small amount of information in the record does not show the distribution or the effect of any extreme times. In general, plots or individual observations can help reveal such features, but the registry record does not report the underlying values.

For count outcomes or event rates, general statistical methods may need to account for over-dispersion, which occurs when variation exceeds what a simple model expects. This trial’s primary outcome is time, not a count, and the registry does not post analysis methods for its secondary outcomes. No claim about over-dispersion being present or handled is therefore supported. More broadly, statistical methods should match the outcome type, randomization structure, and level of measurement; those choices are not described in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The trial summary describes three intended metrics: operation time, drainage volume, and patient pain. The registry also lists hematoma among the secondary outcomes and records four outcome measures. When multiple outcomes are assessed, the chance of at least one apparently unusual result can increase if each is tested separately without an overall plan. In general, a prespecified hierarchy or multiplicity adjustment can help control the interpretation of multiple statistical tests. The registry record does not report whether any such plan was used.

No secondary-outcome results are posted for drainage volume, pain level, or hematoma. The record does not say whether these outcomes were not collected, were collected but not analyzed, or were analyzed but not entered. Their values and their missingness are not reported in the registry record. As a result, it is not possible to assess the intended secondary comparisons or determine whether missing results could affect the overall interpretation.

More generally, missing data require information about who lacks an outcome and why. Statistical approaches depend on the amount and pattern of missingness and on assumptions about the reasons data are absent. The registry does not report missing-data counts, reasons, or handling methods for the primary or secondary outcomes. It also does not describe an intention-to-treat population, a per-protocol population, or other analysis populations. The arm counts for operation time do not substitute for this information.

Because the registry records no analyses, it is not possible to verify whether the reported outcome summaries reflect a prespecified analysis or whether any multiplicity or missing-data methods were applied. These are reporting gaps, not proof that a particular analysis was mishandled.

11. 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 4% reporting threshold.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: infected seroma (3.2%).

The registry records 31 participants at risk in each device group for serious adverse events. It lists one serious adverse event in the Harmonic Scalpel group and zero in the electrocautery group. For other adverse events, it lists zero in each group. Death counts are not reported in the registry record.

The registry names “Infected seroma” as the top serious adverse-event term and gives 3.2%. It does not clarify in the posted record how that term relates to the group-level serious-event count or provide detailed event narratives. The percentage should therefore be read as a recorded adverse-event figure, not as a complete safety profile or a precise comparative risk estimate.

In general, small event counts provide limited information about the frequency of uncommon harms. A count of zero does not establish that an event cannot occur; it means no event was recorded in that group under the registry’s reporting. The record does not provide confidence intervals, exposure time, follow-up duration for adverse events, severity details beyond the serious-event classification, or a full account of ascertainment. These counts describe what was posted and should not be taken as a definitive comparison of safety.

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

The posted data show operation-time summaries for the two device groups: a median of 32.9 minutes, standard deviation 14.7, and n=31 for the Harmonic Scalpel group; and a median of 31.0 minutes, standard deviation 8.1, and n=31 for the electrocautery group. The registry does not report an uncertainty interval or an inferential comparison. These figures describe the recorded observations but do not establish the size or precision of a treatment effect.

They also do not answer the broader question of how the devices compare on drainage, pain, or hematoma. These outcomes are listed as secondary outcomes, but their results are not reported in the registry record. The limited adverse-event counts likewise do not constitute a comprehensive safety assessment. The clinical question was broader than operative duration alone, while the posted results available for interpretation are concentrated on that primary measure and sparse adverse-event summaries.

The trial is listed as randomized and single-masked, but key design details remain unclear. In particular, the registry describes device use by breast side while labeling the model parallel. It does not state whether the same participant contributed observations to both groups or whether the analysis accounted for any within-person relationship. It also does not name the masked party, describe allocation procedures, or explain why the trial status is terminated. These gaps prevent confident reconstruction of the study’s conduct and analysis.

In general, a statistically significant result does not automatically indicate a clinically important difference, and a nonsignificant result does not prove equivalence. Neither conclusion can be drawn from these posted summaries because no test result or confidence interval is reported. Establishing equivalence or noninferiority would also require an appropriate prespecified margin and analysis, which are not reported in the registry record.

The appropriate reading is therefore descriptive and limited: the registry reports two group-level operation-time summaries and a small number of serious adverse events, but it does not provide the inferential results, complete secondary-outcome findings, or methodological detail needed for a fuller comparison. The summaries alone should not be interpreted as demonstrating that either device is superior, equivalent, or safer.

13. Why This Trial Matters Statistically

This trial is statistically instructive because the treatment descriptions and the design label raise a question about the unit of analysis. The registry calls the study parallel, yet describes each device as being used to reduce a breast on a particular side. If observations from both sides of the same participant were included, they would not necessarily be independent. A sound analysis needs to match the structure of the randomization and the observed data. The registry record does not explain that structure, so readers cannot verify that the reported summaries and any intended comparison align.

It also illustrates why a central estimate should be accompanied by information about uncertainty. The posted medians and standard deviations describe the observed operation times, but no confidence interval, test result, or estimated contrast is reported. In general, an estimate and its uncertainty answer different questions: the estimate describes the observed comparison, while uncertainty indicates how much the result may vary under the statistical model. Without both, interpretation remains descriptive.

The mismatch between a median summary and standard deviation as the dispersion measure merits attention. These statistics describe different aspects of a distribution, and readers benefit from a clear explanation of their use. The record does not give such an explanation or the underlying observations. This makes it difficult to assess whether the chosen summaries adequately characterize operation time.

Finally, the lack of posted findings for the intended drainage, pain, and hematoma outcomes limits the trial’s statistical contribution. Transparent reporting of outcome definitions, analysis populations, missing data, and planned methods helps readers distinguish a result that was not observed from one that was not reported. Those details are not reported in the registry record. The case demonstrates how trial design labels and group summaries can be informative, while still leaving important questions unresolved.

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 lists the trial as terminated but does not explain the reason. Without that context, readers cannot assess whether termination was related to recruitment, feasibility, safety, or another circumstance. The record also does not describe the original target enrollment or indicate whether the listed enrollment met the study plan. A sample-size justification is not reported in the registry record.

The arm descriptions refer to treatment of a breast side, but the record does not explain whether both sides of a participant were included, how sides were assigned, or whether the outcome analysis accounted for within-participant dependence. The parallel-model label does not resolve these questions. The identity of the masked party and the allocation procedures are also not reported.

The outcome reporting is incomplete for the stated objectives. Operation time has group summaries, but drainage volume, pain, and hematoma results are not reported in the registry record. The registry does not explain whether these outcomes were unmeasured, unavailable, or omitted from reporting. It does not report missingness, analysis populations, adjustment methods, or a prespecified statistical analysis plan.

The operation-time results are reported as medians with standard deviations, without an explanation of this summary choice, individual observations, confidence intervals, or a direct treatment estimate. The record lists n=31 for each group, but does not clarify the relationship between those counts and the enrolled participants or the unit of analysis. Finally, the serious adverse-event counts are sparse and lack detailed event descriptions, follow-up information, and uncertainty estimates. Together, these limits constrain both the precision and scope of conclusions that can be drawn from the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Harmonic Scalpel Vs. Electrocautery in Breast Reduction Surgery — NCT00819260.
• Registry record last updated 2013-05-20; status last verified 2013-05.
• Results first posted 2013-05-20.
• 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.

18. Record Summary

NCT00819260 is a randomized, single-masked, parallel-model trial sponsored by Dartmouth-Hitchcock Medical Center. It compared the Harmonic Scalpel with electrocautery in breast reduction surgery, enrolled 31, and is listed as terminated. The registry records a start date of 2009-03 and primary completion in 2010-01.

The primary outcome is operation time per breast, in minutes, on the day of surgery. The posted summaries are median 32.9 with standard deviation 14.7 for the Harmonic Scalpel group and median 31.0 with standard deviation 8.1 for the electrocautery group; each group has n=31. No analyses are recorded. Drainage volume, pain, and hematoma are listed as secondary outcomes, but their results are not reported in the registry record.

The record also lists one serious adverse event in the Harmonic Scalpel group and zero in the electrocautery group, with zero other adverse events in both groups. It does not provide enough design or analysis detail to establish the uncertainty of the operation-time comparison or resolve how the side-specific treatment descriptions relate to the parallel-model label.