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 RFS (Radiofrequency Stylet) - Radiofrequency Perforator Vein Treatment Study (NCT01079598), a na na study. The primary outcome is Quality of Life and Clinical Assessments Compared to Pretreatment Baseline..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01079598 |
| Phase | NA |
| Condition | Venous Insufficiency |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 8 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Medtronic Endovascular |
| Results posted | Yes |
2. Clinical Question
Population
People with venous insufficiency and incompetent perforator veins were the intended population. The registry record reports enrollment of 8; further eligibility details are not reported in the registry record.
Intervention
The intervention was radiofrequency ablation with the ClosureRFS Stylet. The study purpose describes successive radiofrequency ablation of incompetent perforator veins.
Comparator
There was no separate comparator group. The study is recorded as single-group, and its planned primary assessment compared follow-up measurements with pretreatment baseline.
Primary question
At the planned 6-month timeframe, how did quality-of-life and clinical assessments compare with pretreatment baseline? The registry record says the analysis could not be completed because enrollment was very low and available data were limited.
The study was intended to examine changes after treatment rather than estimate a contrast between treatment and a control. Its brief summary describes a purpose of demonstrating improvement in immediate treatment outcomes from successive radiofrequency ablation. The primary outcome description, however, specifies periodic CIVIQ2 and VCSS assessments compared with pretreatment baseline at follow-up visits, with a 6-month timeframe. The registry record does not provide an estimate of change, the number of completed assessments, or results at any follow-up.
Secondary outcomes listed in the registry concern cessation of flow through the perforator vein, CEAP classification, and cessation of reflux flow through the perforator vein. They describe clinical or vein-flow outcomes, distinct from the quality-of-life and clinical-assessment comparison named as primary. No findings for those outcomes are reported. As a result, the clinical question is identifiable from the planned assessments, but the posted record does not answer it with outcome data.
3. Trial Design
The registry identifies this as a prospective, multicenter study of the ClosureRFS Stylet for treatment of incompetent perforators. The intervention was radiofrequency ablation, and the treatment arm description also specifies RF ablation with the ClosureRFS Stylet. Enrollment is recorded as 8. The study model is single-group, with no separate control arm described. Allocation and masking are recorded as NA and none, respectively.
The planned primary outcome was quality of life and clinical assessments compared with pretreatment baseline, with a 6-month timeframe. The description says periodic CIVIQ2 and VCSS assessments were planned for comparison at each follow-up visit. This is a within-group follow-up design: participants' post-treatment measurements were to be considered relative to their own pretreatment baseline, rather than compared with outcomes from a concurrent control group.
The record lists three secondary outcomes: cessation of flow through the perforator vein, CEAP classification, and cessation of reflux flow through the perforator vein. The record identifies the condition as venous insufficiency and the sponsor as Medtronic Endovascular. The recorded start is 2010-03, the primary completion is 2011-01, and the status is terminated. The reason for termination is not reported in the registry record.
Although the official title describes the study as prospective and multicenter, the registry record does not give the number or locations of centers. It also does not report further details about eligibility, treatment delivery, follow-up schedules, or how many participants completed any particular assessment. These omissions limit what can be reconstructed about implementation. Most importantly for interpreting the design, there is no concurrent comparator and the registry reports no completed primary analysis. The design can therefore describe a planned baseline-to-follow-up assessment, but the posted record supplies no estimate of the change or basis for separating treatment-related change from other influences over time.
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 | Treatment |
|---|---|
| STARTED | 8 |
| COMPLETED | 8 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: Analysis was not able to be completed due to very low enrollment and limited data available. No results available.
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 | Treatment |
|---|---|---|
| Participants analysed | 8 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 7 |
| Age, Categorical: >=65 years | Participants | 1 |
| Sex: Female, Male: Female | Participants | 4 |
| Sex: Female, Male: Male | Participants | 4 |
| Region of Enrollment: United States | participants | 8 |
6. Primary Endpoint
The registry lists the primary outcome as Quality of Life and Clinical Assessments Compared to Pretreatment Baseline., measured over 6 months.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary outcome is titled “Quality of Life and Clinical Assessments Compared to Pretreatment Baseline.” It was planned to use periodic CIVIQ2 and VCSS assessments, with measurements at follow-up visits compared with pretreatment baseline. The registry gives a 6-month timeframe. It does not report the unit, parameter, or dispersion for the outcome, and the description says that analysis and study results are inconclusive because enrollment was very low and data were limited.
In general, quality-of-life and clinical assessments can capture different aspects of a participant's status: an assessment of quality of life addresses a different perspective from a clinical assessment. Following measurements over time can describe whether observed scores changed from a pretreatment reference point. Such a comparison is useful for characterizing change within a treated group, but by itself it does not establish what would have happened over the same period without treatment. Without reported scores, changes, uncertainty estimates, or completed analyses, the registry record does not show the direction or precision of any primary outcome change.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The key statistical fact is that the registry record reports no primary outcome results. It states that the planned analysis could not be completed because enrollment was very low and available data were limited, and it labels the study results inconclusive. The record lists enrollment of 8, but it does not report the number with usable baseline and follow-up measurements or provide outcome estimates. Accordingly, there is no reported change in CIVIQ2 or VCSS to interpret, and no confidence interval or other measure of uncertainty for the primary endpoint.
This absence of an estimate is not evidence that the outcome stayed unchanged. It also does not establish that the outcome improved. The study's brief summary states its purpose, not a result. The primary outcome description gives the planned comparison and explicitly notes the limitations on analysis. Keeping those separate prevents a stated study aim from being mistaken for a finding.
The single-group design makes the planned comparison a follow-up-versus-baseline assessment. In general, such a comparison can describe how measurements among observed participants differ over time. It cannot, without a suitable comparator, isolate the effect of treatment from changes that could occur over time for other reasons. This design issue remains even if paired measurements are available; in this record, the necessary outcome values are not reported in the registry record.
The registry lists secondary outcomes related to perforator-vein flow, reflux, and CEAP classification, but no results or analyses for them are reported. The record also lists zero analyses. The planned outcomes therefore cannot be treated as evidence of an observed clinical or anatomical change. Nor can the absence of a posted analysis be interpreted as a null result or as proof that no changes occurred.
The safety information is separate from the missing efficacy results. The record reports one serious adverse event in the treatment group, identified as Thrombus Extension, and reports 0 participants with other adverse events. The event information describes what was recorded in this small study; it does not establish a general rate or a causal relationship. Deaths are not reported in the registry record.
Overall, the posted results do not permit an estimate of the size, direction, or precision of change in the primary outcome. The most defensible interpretation is that the registry documents a planned assessment and a terminated study with limited enrollment, but does not provide analyzable primary findings. Any stronger conclusion about clinical benefit, lack of benefit, or comparative effect would go beyond the reported results.
9. Statistical Methods Explained
The registry describes a single-group study. This means the reported design has one treatment group and no separate control group. The planned primary comparison was between follow-up assessments and pretreatment baseline. It was not a randomized comparison of treatment against an alternative. The registry records allocation as NA and masking as none. These design details matter because the statistical question is about change over time within the treated group, not a difference between randomized groups.
What does a baseline comparison estimate?
In general, a baseline-to-follow-up comparison examines how a measurement changes among participants with observations at both time points. A paired analysis can use the relationship between each participant's baseline and follow-up values. That can be useful when the same people are assessed repeatedly. However, the registry does not report the actual CIVIQ2 or VCSS measurements, the number of paired observations, or the analysis used. It is therefore not possible to determine how the planned comparison would have been carried out or what it would have estimated in practice.
In general, a within-group change is not the same estimand as a treatment-versus-control effect. A baseline comparison does not reveal what the same participants' outcomes would have been without treatment. Changes over time may reflect treatment, the course of the condition, other care, measurement variation, or other factors. With no concurrent comparator, the design does not separate those possibilities. This is a limitation of the design, not a calculation that can be repaired by adding a confidence interval to an unreported result.
What would uncertainty measures contribute?
In general, a confidence interval describes a range of estimates compatible with the data and the method's assumptions, and indicates the precision of an estimate. A point estimate without an uncertainty measure can leave readers unsure how much the estimate might vary. Here, neither a primary outcome estimate nor its uncertainty is reported. The record's statement that results are inconclusive reflects the lack of sufficient analyzable information described in the outcome entry; it is not a numerical estimate of no change.
When sample sizes are small, estimates can be imprecise and may depend strongly on the observations available. That general concern is relevant to a record with enrollment of 8, but the actual precision cannot be assessed without outcome values and analysis details. There is no reported standard error, confidence interval, or p-value for the primary outcome. No inferential result should be reconstructed from enrollment alone.
How should the planning illustrations be understood?
In general, sample-size planning asks how many participants might be needed under specified assumptions to detect a stated effect with a selected error rate and power. The registry's planning assumptions describe an illustration using a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of the observed effect. Those assumptions describe a planning calculation, not the actual single-group trial design. Any displayed sample-size values based on them would be hypothetical planning quantities, not participant counts observed in this study and not observed power.
The assumptions describe equal allocation between two arms even though the actual study is recorded as single-group. That makes the distinction between an illustration and the implemented design especially important. A planning calculation cannot turn a single-group study into a randomized comparison, and it cannot supply a missing estimate of treatment effect. The registry does not report a trial-specific sample-size justification, so the planning illustration should not be read as the original enrollment target or as evidence that the study met a prespecified design requirement.
More generally, sample-size calculations depend on assumptions about the outcome, variability, target effect, significance level, and analysis. If those assumptions do not match the design or data, the resulting planning quantity may not answer the question readers have about this study. The registry entry does not report enough outcome information to evaluate such assumptions for the primary endpoint. The planning method alone is not a substitute for results.
Why can extra variability affect analysis?
In general, over-dispersion means observed variability is greater than a statistical model assumes. If a model understates variability, it can make uncertainty appear smaller than it is. Appropriate modeling depends on the outcome type and observed data. The registry record does not report an outcome distribution, a fitted model, or evidence of over-dispersion, so no claim can be made that this issue occurred in this study. It is a general consideration rather than a finding from the record.
Similarly, repeated measurements can require methods that account for the fact that observations from the same participant are related. Treating each measurement as independent when it is not can misstate uncertainty. The registry describes periodic assessments, but does not report the number or timing of completed visits or the method planned for repeated measurements. The statistical handling of within-participant correlation is therefore not reported in the registry record.
There is no reported completed analysis to assess for adjustment, model choice, or sensitivity to assumptions. The registry record says the results were inconclusive because of low enrollment and limited data, and lists zero analyses. The appropriate statistical reading is therefore descriptive: the study's intended outcome and design can be identified, but its primary treatment-related estimate and precision cannot be evaluated from the posted record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary outcome and three secondary outcomes. The primary outcome description names periodic CIVIQ2 and VCSS assessments compared with pretreatment baseline; secondary outcomes concern perforator-vein flow, CEAP classification, and reflux flow. When several outcomes or repeated follow-up comparisons are planned, there can be multiple opportunities to observe a result that appears notable by chance. In general, multiplicity procedures can address that issue by controlling how conclusions are drawn across a family of tests. The registry record does not report a multiplicity strategy, so it is not possible to determine whether or how the planned comparisons would have been adjusted.
The record reports zero analyses and says the primary analysis could not be completed because enrollment was very low and available data were limited. It does not provide a completed analysis population, outcome-specific denominators, or a participant flow account. It is therefore not possible to establish who contributed to each planned outcome or whether follow-up was complete.
Missing-data methods are not reported in the registry record. In general, missing follow-up measurements can affect a longitudinal comparison, particularly if availability of measurements is related to participants' outcomes or circumstances. The record does not describe the extent or pattern of missing outcome data, any imputation, or any sensitivity analysis. It would be inappropriate to assume that all enrolled participants had complete follow-up or that missing observations had no effect.
The registry also does not report a defined intention-to-treat or per-protocol analysis population. No such population can be inferred from enrollment alone. Given the lack of outcome estimates and analysis details, neither multiplicity nor missing-data handling can be evaluated from the posted results.
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 |
|---|---|---|---|
| Treatment | 1 | 8 | 12.5% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Treatment | 0 of 8 |
Most frequent serious adverse event terms
| Event term | Organ system | Treatment |
|---|---|---|
| Thrombus Extension | Vascular disorders | 1 of 8 |
Serious events with the highest arm-level rate: thrombus extension (12.5%).
The registry reports one serious adverse event in the Treatment group, among 8 at risk. The listed serious event term is Thrombus Extension, reported as 12.5%. It reports 0 participants with other adverse events among 8 at risk. The death count is not reported in the registry record.
These entries are counts recorded for this study, not estimates that should be assumed to apply to other populations or settings. In general, safety counts from a small study provide limited information about how often an event may occur; uncertainty around an event frequency can be substantial when few participants are observed. The record does not provide a comparator group, so these data cannot establish whether the event frequency differed from another treatment or from no treatment.
The registry entry identifies the event as serious but does not provide further event details, timing, outcome, or an assessment of causal relation to treatment. Those details are not reported in the registry record. The reported serious event should not be conflated with the primary quality-of-life and clinical-assessment outcome, for which results are unavailable.
12. What the Result Does, and Does Not, Mean
The registry record documents a prospective, multicenter, single-group study of radiofrequency ablation with the ClosureRFS Stylet for incompetent perforator veins. It records enrollment of 8 and a planned primary comparison of quality-of-life and clinical assessments with pretreatment baseline at follow-up, within a 6-month timeframe. It also lists secondary vein-flow and CEAP outcomes. These registry entries describe the study's intent and design.
The record does not provide primary outcome results. Its primary outcome description states that analysis and study results are inconclusive because enrollment was very low and available data were limited. Consequently, there is no reported estimate showing whether CIVIQ2 or VCSS assessments changed, how large any change was, or how precise an estimate might be. This does not mean that no change occurred; it means that the posted record does not report an analyzable result.
The single-group design is also important to what could be concluded even if baseline-to-follow-up results were available. A within-group change would describe observed change among assessed participants, but without a control group it would not by itself distinguish treatment effects from other influences over time. No comparative treatment effect can be estimated from the design as recorded.
The safety entry reports one serious adverse event, identified as Thrombus Extension, and 0 participants with other adverse events; deaths are not reported in the registry record. Those counts are descriptive and do not establish a general safety profile or a causal link. The reason for termination, missing-data handling, and the planned statistical analysis are not reported in the registry record. Thus the study record is informative about the intended question and the limits of the available data, but it does not resolve the treatment's effect on the primary outcome.
13. Why This Trial Matters Statistically
This study is statistically instructive because it distinguishes a clinical question from an answer supported by data. The registry clearly identifies an intended baseline-to-follow-up assessment, yet also states that low enrollment and limited available data prevented completion of analysis and left results inconclusive. A specified endpoint and timeframe do not, by themselves, produce an estimate that can be interpreted.
The record also illustrates why design determines the scope of inference. A single-group study can describe changes over time within the group, but it has no concurrent comparison for separating treatment-related changes from other changes. This distinction is important when reading reports that use baseline as the reference. Baseline is a useful measurement point, but it is not a substitute for a control group when the question is a comparative treatment effect.
It also matters that the planned outcome combines quality-of-life and clinical assessments, while secondary outcomes address vein flow and classification. These outcomes represent different kinds of information and should not be treated as interchangeable. Because no findings are posted, readers cannot determine whether they pointed in a similar direction or how uncertain any estimates were.
Finally, the record shows why safety counts and outcome analyses must be read separately. The registry reports a serious adverse event, but that entry does not fill the gap in the primary outcome analysis or establish a general risk estimate. For researchers, the central statistical lesson is to distinguish planned comparisons, observed data, and conclusions—and to avoid drawing an efficacy or comparative claim when the outcome estimate is not available.
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 most direct limitation is the absence of reported primary results. The registry explicitly says the analysis could not be completed because of very low enrollment and limited data, and records no analyses. No outcome estimates, measures of uncertainty, or results for the listed secondary outcomes are available. This prevents assessment of the direction, size, and precision of any observed change.
Enrollment is recorded as 8, but the record does not give the number with complete baseline and follow-up assessments. It does not describe the extent or pattern of missing data, explain how missing observations were handled, or define the analysis population. The reason for termination is not reported in the registry record. These gaps prevent a detailed account of how participants moved through the planned follow-up and analysis.
The single-group design has no separate control group. A comparison with pretreatment baseline could describe within-group change, but it would not isolate treatment effects from other changes over time. The registry also records no masking. The record does not report a statistical analysis plan, model specification, or multiplicity procedure, so those methods cannot be evaluated.
The official title identifies the study as multicenter, but the number and locations of centers are not reported in the registry record. Further eligibility criteria, treatment implementation details, and follow-up completion are also not reported. The safety information is limited to the posted event counts; timing, outcomes, and causal assessments are not reported. Together, these limitations mean the registry supports a description of the intended study and its reporting gaps, not a firm estimate of treatment effect or a broadly applicable safety conclusion.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: RFS (Radiofrequency Stylet) - Radiofrequency Perforator Vein Treatment Study — NCT01079598.
- Registry record last updated 2017-05-05; status last verified 2017-03.
- Results first posted 2017-05-05.
- 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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Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
The record concerns a prospective, multicenter, single-group study of radiofrequency ablation with the ClosureRFS Stylet for incompetent perforator veins in people with venous insufficiency. Enrollment is recorded as 8. The study status is terminated, with the reason not reported in the registry record.
The planned primary outcome compared periodic CIVIQ2 and VCSS assessments with pretreatment baseline, with a 6-month timeframe. The registry states that analysis and results were inconclusive because enrollment was very low and available data were limited; no primary results or completed analyses are reported. Secondary outcomes addressed perforator-vein flow, CEAP classification, and reflux flow, without posted results.
The safety entry reports one serious adverse event, Thrombus Extension, and 0 participants with other adverse events. Deaths are not reported in the registry record. The single-group design and missing outcome analyses limit conclusions about treatment-related change and its precision.