A Pilot Study Assessing the Effect of Lymphaticovenous Micro-Anastomosis in the Treatment of Postmastectomy Lymphedema: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Pilot Study Assessing the Effect of Lymphaticovenous Micro-Anastomosis in the Treatment of Postmastectomy Lymphedema (NCT02020837), a na early/phase 1 study. The primary outcome is Changes Relative to Baseline in the Volume of the Affected Limb at 3 and 6 Months From Surgery.

2. Clinical Question

The study summary describes the aim as assessing the impact of the procedure on volume reduction and quality of life. Those statements describe the study’s aims and hypothesis, not observed findings. The registered primary outcome is volumetric change; a quality-of-life outcome is not reported in the registry record. With no comparator and no computed outcome, the central question remains descriptive rather than a controlled estimate of whether the procedure changed limb volume. The record identifies the study as early phase 1 and reports that it was terminated.

3. Trial Design

This was a single-group pilot study of lymphaticovenous micro-anastomosis in postmastectomy lymphedema. The registry record lists the phase as early phase 1, allocation as NA, masking as none, and the study model as single group. Enrollment was 2. These design details mean that the registry describes a small group receiving the procedure, not a randomized comparison between intervention and control groups.

The intervention is listed as a procedure named lymphaticovenous micro-anastomosis. The summary states that the study would assess whether multiple micro-anastomoses in the distal arm were associated with reduced volume and improved quality of life. The arm description contains no additional details. Specifics about procedural delivery, eligibility criteria, follow-up procedures, or any co-interventions are not reported in the registry record.

The study start is recorded as 2014-09, and primary completion as 2015-12-03. Its status is terminated. The primary outcome timeframe is 3 and 6 months from surgery. The record explains that early termination led to small numbers of subjects and that outcome measures were not computed because the data would not be statistically relevant. The reason for termination beyond that statement is not reported in the registry record.

There is one registered outcome measure and no listed analyses. No randomization or masking is recorded, and there is no control group. Consequently, the design cannot separate changes after the procedure from changes that might occur over time for other reasons. Even a measured before-and-after change would be a within-group observation rather than a randomized treatment effect. Here, the registry does not provide computed primary outcome data, so it supports no numerical estimate of change.

The sponsor is the University of Arkansas. Details of a protocol, a sample-size justification for the actual study, interim analyses, or a prespecified statistical analysis plan are not reported in the registry record. Those omissions matter when judging how the small pilot was intended to be analyzed, but they do not alter the basic design description: this was a terminated, single-group study with two enrolled participants and no reported computed primary outcome.

4. Participant Flow and Accounting

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

Overall Study

Analysis population for the primary outcome, as defined in the registry: Early termination leading to small numbers of subjects.Outcome measures not computed because data would not be statistically relevant.

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 Changes Relative to Baseline in the Volume of the Affected Limb at 3 and 6 Months From Surgery, measured over 3 and 6 months from surgery.

The primary endpoint is change relative to baseline in the volume of the affected limb, assessed at 3 and 6 months from surgery. The registry describes a lymphatic volumetric assessment that evaluates how the affected-limb volume differs from its baseline measurement at those follow-up times. The endpoint therefore focuses on a measurable physical characteristic rather than a comparison with a separate control group.

As a general statistical concept, a baseline-referenced measure can describe whether a participant’s measurement differs from that participant’s starting measurement. Repeated measurements can also describe how such change varies across follow-up times. Without a comparator, however, an observed within-person or within-group change would not by itself establish that the procedure caused the change. Other influences over time cannot be distinguished through this design alone.

The registry record says the primary outcome measures were not computed because early termination resulted in small numbers of subjects and the data would not be statistically relevant. It therefore provides no baseline or follow-up volume values, no estimated change, and no uncertainty interval for either time point. Quality-of-life improvement appears in the study hypothesis, but a quality-of-life measure is not reported among the registered outcome measures. The endpoint as registered is thus a planned volume assessment, not a reported result.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record identifies a single-group, early phase 1 study with no masking and allocation listed as NA. These design descriptors determine what kinds of statistical conclusions could be supported. In a randomized controlled comparison, an effect estimate can compare outcomes across allocated groups. In a single-group study, measurements can instead describe the enrolled participants over time. Because no comparator group is recorded, a between-group treatment contrast is not available.

What does a baseline-referenced endpoint measure?

As a general statistical concept, change relative to baseline compares a follow-up measurement with a participant’s measurement before the intervention. Such a measure can communicate the direction and magnitude of observed within-participant change, and group summaries can describe the observed changes across participants. The primary endpoint was designed to assess affected-limb volume at 3 and 6 months from surgery relative to baseline. The registry record reports that the measure was not computed, so neither the individual changes nor an overall summary is available.

A change measure is not automatically a causal effect. General statistical reasoning: values may change over time for reasons unrelated to the intervention. With no comparison group, the observed change, if calculated, would combine any intervention-associated change with other temporal influences. The lack of randomization and a comparator therefore limits causal interpretation. In this record, that design limitation accompanies the more fundamental absence of computed outcome data.

What would an uncertainty interval communicate?

As a general explanation, a confidence interval describes the precision of an estimate under the assumptions of the method used to construct it. A narrow interval indicates greater statistical precision than a wide interval, while an interval spanning a range of plausible values conveys uncertainty about the effect’s magnitude. It does not guarantee that a study is free from bias or that all values in the interval are equally likely. No confidence interval or primary endpoint estimate is reported in the registry record, so precision cannot be assessed for limb-volume change.

With only two enrolled participants, any summary based on the observed participants would have limited capacity to characterize variability across a broader population. General statistical reasoning: estimates from very small groups can be strongly influenced by individual observations, and a small dataset often yields substantial uncertainty. The registry’s own explanation is that early termination led to small numbers and outcome measures were not computed because the data would not be statistically relevant. There is no basis in the record for replacing that decision with an unreported estimate.

How should significance testing be read?

A significance test, in general, evaluates how compatible observed data are with a specified null hypothesis under a statistical model. A p-value does not measure the size or clinical importance of an effect, and a non-significant result does not establish that there is no effect. Here, no primary outcome analysis or p-value is reported. The registry lists no analyses, so there is no reported statistical test to interpret.

Planning illustrations associated with the study use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. Those assumptions describe planning illustrations, not the design actually recorded for this study. The trial itself is single-group, and the registry does not report a sample-size justification for its design. The illustrations must not be interpreted as observed power or as evidence that the study had a particular chance of detecting an effect. No resulting participant-per-arm values are reported in the registry record available for this analysis.

Why can over-dispersion matter?

As a general concept, over-dispersion occurs when data vary more than a chosen statistical model expects. If a model assumes less variability than is present, standard errors and uncertainty estimates can be too small, making results appear more precise than they are. Methods that account for extra variation may be appropriate in some settings. The registry record does not report an analysis model for the primary endpoint, and it does not provide data from which over-dispersion or another variance feature could be assessed. It would be inappropriate to attribute an analysis choice to the investigators.

Other statistical details are also not reported in the registry record, including the planned form of the primary endpoint summary, handling of repeated measurements, covariate adjustment, missing-data procedures, interim analyses, and any formal stopping rule. The record’s statement about early termination and uncomputed outcomes is relevant, but it does not fill in those methodological details. Statistical explanations can clarify what such choices would mean in general; they cannot establish which choices were made for this study.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists one outcome measure: change relative to baseline in affected-limb volume at 3 and 6 months from surgery. These are two specified follow-up times for the primary measurement. When several outcomes, time points, or statistical tests are examined, multiplicity can increase the chance of finding an apparently notable result by chance. General methods for addressing multiplicity include prespecifying a primary comparison or adjusting inference across multiple tests. The registry record does not report a multiplicity strategy or a statistical analysis plan, and it reports no computed outcome analyses.

The presence of two follow-up times does not reveal whether the investigators intended separate tests, a joint analysis, or a particular hierarchy. Those details are not reported in the registry record. Because no endpoint values or tests are reported, there are no statistical findings for which multiplicity adjustment can be evaluated.

Missing-data handling is also not reported in the registry record. The record states that outcome measures were not computed because early termination led to small numbers of subjects and the data would not be statistically relevant. It does not state whether any baseline or follow-up measurements were collected, whether measurements were missing, or what rules would have been used to handle missing observations. No imputation method or sensitivity analysis is reported.

Analysis populations are not described in the registry record. It does not specify an intention-to-treat population, a per-protocol population, or another analysis set. Since the study was single-group and the primary endpoint was not computed, the registry provides no analysis-population counts beyond the overall enrollment of 2. The absence of these details prevents assessment of whether any potential departures from the intended follow-up would have affected an analysis.

11. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The registry reports adverse-event counts for the lymphaticovenous micro-anastomosis group. Two participants were at risk for serious adverse events, and zero were recorded as affected. Two participants were at risk for other adverse events, and zero were recorded as affected. Deaths are recorded as zero, and no serious adverse-event terms are listed.

These figures are counts in the enrolled group, not a comparison with another group. They should be read as the events recorded in the registry for this study, not as proof that an event is impossible or that the procedure has no safety risks. General statistical reasoning: when a study includes very few participants, the absence of recorded events provides limited information about how often events might occur in a larger population. The registry does not provide additional detail about event definitions, surveillance procedures, or event timing, so those aspects are not reported in the registry record.

The study status is terminated, and the primary outcome measures were not computed. The adverse-event counts do not replace the missing efficacy outcome information, and they cannot establish a benefit-risk balance. They are a narrow description of the safety counts recorded for the two participants.

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

The registry record supports a limited set of conclusions about the study itself. It was a terminated, single-group, early phase 1 study of lymphaticovenous micro-anastomosis, with enrollment of 2. The planned primary endpoint was affected-limb volume change relative to baseline at 3 and 6 months from surgery. The record states that outcome measures were not computed because early termination led to small numbers and the data would not be statistically relevant.

That means no numerical result is available for the primary question. The record does not report a volume change, an uncertainty interval, or a statistical test. It cannot establish the size, direction, or precision of any change in limb volume. It also cannot support the conclusion that there was no change. A missing estimate is not a null finding.

The study summary refers to a hypothesis about volume reduction and quality-of-life improvement. A hypothesis is a research expectation, not an outcome. The registry does not report a quality-of-life outcome measure or quality-of-life results. Nor does it contain a comparator group that could provide a controlled estimate of change attributable to the procedure. Even if a within-group change had been reported, the design alone would not separate the intervention’s contribution from other changes over time.

The safety counts record zero serious adverse events, zero other adverse events, and zero deaths among the two participants at risk in the corresponding categories. These counts are specific to the small group and the registry’s reporting. They do not establish the absence of risk in a broader population. No additional interpretation of event severity or timing is reported.

In statistical terms, the record describes an intended assessment but provides no computed primary outcome with which to answer it. It is therefore not evidence for or against a particular effect. It documents why the registry does not offer an inferential result and identifies the central constraints: very small enrollment, early termination, no control group, and no reported outcome analysis. Claims beyond those points would exceed what the registry record reports.

13. Why This Trial Matters Statistically

This study matters statistically because it illustrates the difference between a research question and an estimate that can answer it. The registered question concerns change in affected-limb volume from baseline at 3 and 6 months after surgery. The registry record states that the outcome measures were not computed. Without a computed endpoint, there is no estimate to interpret, no measure of precision, and no statistical test to evaluate.

The design further defines what an estimate could have meant. A single-group study can describe outcomes among enrolled participants, but it does not provide a concurrent control comparison. General statistical reasoning: changes over time may have multiple explanations, so a before-and-after description alone is not equivalent to a causal treatment effect. This distinction is especially important when a study’s stated hypothesis is worded in terms of what an intervention may do.

The small enrollment and early termination are also central statistical details, rather than incidental details. The registry explicitly connects early termination and small numbers with the decision not to compute outcome measures. A result from a very small group would generally be imprecise and sensitive to individual observations; in this case, the record does not report an estimate at all. Statistical planning illustrations cannot substitute for observed outcomes or turn this study into a randomized comparison.

The record also shows why safety counts need context. Zero recorded events among two participants is a descriptive count in a small group, not a precise estimate of risk. It should not be mistaken for proof that events cannot occur.

For clinical researchers and biostatisticians, the practical lesson is to distinguish planned endpoints, hypotheses, study design, and reported results. The first three are described in the registry; computed primary findings are not. Accurate interpretation requires preserving that distinction rather than treating the study aim as an observed result or the absence of a result as evidence of no effect.

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.

Several limitations are specific to this registry record. Enrollment was 2, and the study was terminated. The record states that early termination led to small numbers of subjects and that outcome measures were not computed because the data would not be statistically relevant. As a result, the primary endpoint has no reported numerical result at either planned follow-up time.

The study was single group, with allocation listed as NA and masking as none. There was no control group, and the study was not a randomized comparison. Any potential description of participants over time would therefore lack a concurrent comparator for distinguishing changes associated with the procedure from other changes. In this case, even a descriptive endpoint calculation is absent from the registry record.

The registered primary endpoint concerns affected-limb volume relative to baseline at 3 and 6 months from surgery. Baseline values, follow-up values, and details about whether those measurements were collected are not reported in the registry record. Missing-data methods, analysis populations, statistical model, and multiplicity handling are also not reported. The registry lists no analyses.

The summary’s quality-of-life hypothesis is not accompanied by a registered quality-of-life outcome measure or result. The record also offers little detail about the procedure or follow-up beyond the intervention name and the stated time points. The reason for termination beyond the explanation about small numbers and uncomputed outcomes is not reported in the registry record.

Finally, the adverse-event counts come from only two participants, and the record provides no comparator or additional event detail. They are therefore limited descriptive information. Together, these features leave the registry useful for understanding the intended question and the study’s constraints, but insufficient for estimating the procedure’s effect or drawing broader conclusions from its outcome data.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: A Pilot Study Assessing the Effect of Lymphaticovenous Micro-Anastomosis in the Treatment of Postmastectomy Lymphedema — NCT02020837.
• Registry record last updated 2018-06-27; status last verified 2018-04.
• Results first posted 2018-04-09.
• 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

The registry record describes a University of Arkansas-sponsored, early phase 1, single-group study of lymphaticovenous micro-anastomosis for postmastectomy lymphedema. The study began in 2014-09, had primary completion recorded as 2015-12-03, and is listed as terminated. Enrollment was 2; allocation was NA, and masking was none.

The primary endpoint was change relative to baseline in affected-limb volume at 3 and 6 months from surgery. The record states that outcome measures were not computed because early termination led to small numbers and the data would not be statistically relevant. No analyses are listed. Serious adverse events, other adverse events, and deaths are each recorded as zero, with two participants at risk in each adverse-event category.

The record therefore documents the study’s aim and design but does not provide a computed primary outcome result. A quality-of-life result, statistical analysis plan, and further details about missing-data handling are not reported in the registry record.