Radiofrequency Ablation vs Laser Ablation of the Incompetent Greater Saphenous Vein: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Radiofrequency Ablation vs Laser Ablation of the Incompetent Greater Saphenous Vein (NCT02236338), a randomized phase 4 study. The primary outcome is Percentage of Participants Without Recurrent Clinical Symptoms of an Incompetent Greater Saphenous Vein After Treatment..

2. Clinical Question

The trial also lists incidence rate of acute complications as a secondary outcome. Its stated aim was to compare complications and outcomes for the two methods. The registry record does not provide a posted analysis for that secondary outcome. The central clinical question is therefore comparative, but the posted primary results do not by themselves establish whether the observed arm-level percentages differ beyond what could plausibly arise from sampling variability.

3. Trial Design

The registry describes a prospective, randomized, parallel-group Phase 4 trial comparing two procedures for chronic venous insufficiency. One arm received radiofrequency ablation using a ClosureFAST radiofrequency catheter; the other received laser ablation using an EVLT 980nm diode laser system. Both arm descriptions identify the procedure as ablation of the incompetent greater saphenous vein. The allocation is recorded as randomized, while masking is recorded as none. Thus, the registry indicates an open-label comparison rather than a masked trial.

The registry lists enrollment as 200. The posted primary outcome lists 87 participants for Radiofrequency Ablation and 89 for Laser Ablation. These are the arm-level denominators associated with the reported primary outcome; the record does not explain how they relate to enrollment, whether participants were excluded from this outcome, or whether every randomized participant contributed data. The reasons for any difference between enrollment and outcome denominators are not reported in the registry record.

The primary endpoint is the percentage without recurrent clinical symptoms of an incompetent greater saphenous vein after treatment. Its timeframe is annual follow up, up to 75 months. The outcome description reports mean long-term follow-up of 44 months, with a range of 12–64 months, in the EVLA group and 42 months, with a range of 12–75 months, in the RFA group. The registry also lists incidence rate of acute complications as a secondary outcome. It records four outcome measures, but only one secondary outcome is identified in the posted results summary.

The registry lists Virginia Commonwealth University as sponsor, a start date of 2008-09, primary completion on 2016-08-11, and status as completed. Details about the random sequence, allocation concealment, recruitment sites, eligibility criteria, follow-up schedule at individual visits, and protocol deviations are not reported in the registry record. These omissions limit assessment of how the trial was conducted beyond its broad randomized, prospective, parallel design.

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: The mean long-term followup in the EVLA group was 44 (12-64) months, and the mean long-term follow-up in the RFA group was 42 (12-75) months.

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 Percentage of Participants Without Recurrent Clinical Symptoms of an Incompetent Greater Saphenous Vein After Treatment., measured over Annual follow up, up to 75 months.

The primary endpoint measures the percentage of participants who did not have recurrent clinical symptoms of an incompetent greater saphenous vein after treatment. It is a clinical outcome rather than a device-function measure: it focuses on whether symptoms returned during follow-up. The registry specifies annual follow up, up to 75 months, and describes the result as a percentage of total participants.

In general, an outcome that captures symptom recurrence can help describe the durability of a treatment from the participant’s clinical perspective. It complements information about acute complications, which the registry lists as a secondary outcome. These outcomes address different aspects of treatment: recurrent symptoms concern later clinical status, while acute complications concern events associated with the treatment period. The record does not provide a more detailed definition of recurrence, the symptoms counted, how recurrence was assessed, or whether an assessor was blinded.

The primary results are 79.3 for Radiofrequency Ablation, with 87 participants listed, and 77.5 for Laser Ablation, with 89 participants listed. The outcome description also reports mean follow-up of 42 months in the RFA group and 44 months in the EVLA group, with ranges of 12–75 and 12–64 months, respectively. Unequal follow-up duration can affect interpretation of a simple percentage if participants had different opportunities for symptoms to recur. The registry does not report a time-to-event analysis or an adjustment for follow-up duration, so the posted percentages should be read as the stated arm-level summaries rather than as rates over a common exposure period.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The record identifies this as a randomized, prospective, parallel-group comparison, but it does not report a statistical analysis plan. The methods below distinguish what the registry says from general statistical principles that help explain how results of this kind are usually interpreted.

What does randomization contribute?

The registry records random allocation to Radiofrequency Ablation or Laser Ablation. General statistical principle: random assignment is intended to balance both measured and unmeasured prognostic factors across treatment groups on average. That balance supports a causal comparison when allocation is properly implemented and participants are analyzed in a way that preserves the randomized groups. The registry does not report how the random sequence was generated, whether allocation was concealed, or which analysis population was used. Those details are not reported in the registry record, so the actual implementation cannot be assessed from the posted description alone.

The record specifies a parallel model and no masking. General statistical principle: a parallel design assigns participants to one treatment group and follows outcomes in that group. Masking can reduce some forms of expectation or measurement bias, but is not always feasible for procedural comparisons. Here the registry records no masking; it does not describe who assessed symptoms, whether outcome assessors knew the assigned procedure, or how recurrence was confirmed. The implications for outcome assessment therefore cannot be determined from the registry record.

What does the endpoint summary represent?

The primary result is reported as a percentage without recurrent clinical symptoms, separately by arm. The record also gives the participant count associated with each arm-level value. General statistical principle: a percentage is a descriptive summary of the outcome in a group. It is not itself a measure of the uncertainty around a comparison between groups. To estimate that uncertainty, an analysis generally needs a defined contrast and an appropriate standard error or confidence interval. Neither is reported for the primary comparison in the registry record.

The endpoint is followed annually, up to 75 months, and the outcome description reports different mean follow-up durations and ranges between the groups. General statistical principle: when follow-up differs, a proportion that ignores timing may not fully account for differing opportunities to experience an event. Survival or time-to-event methods can use information about event timing and censoring, but such methods require appropriate data and assumptions. The registry does not report event times, censoring details, or a time-to-event estimate, so it is not possible to determine whether those methods were used.

Why do confidence intervals and p-values matter?

General statistical principle: a confidence interval expresses the statistical uncertainty around an estimated quantity, such as a group-specific percentage or an arm-to-arm contrast. Its width reflects both the observed data and assumptions of the method. A p-value, when calculated for a prespecified hypothesis, describes how compatible the observed data are with that hypothesis under the test’s assumptions; it is not the probability that a treatment is effective or that the null hypothesis is true. The registry does not report a confidence interval or p-value for the primary endpoint. Without an interval or other uncertainty estimate, the precision of the reported percentages and the comparative contrast cannot be judged from the record.

General statistical principle: absence of a reported statistically significant result is not evidence of equivalence. Demonstrating equivalence or noninferiority requires a specified margin and an analysis designed for that question. The registry’s stated aim is to compare the methods and assess whether one is superior, but an equivalence or noninferiority margin is not reported in the registry record. No conclusion about equivalence or noninferiority can be drawn from the posted arm-level percentages alone.

What do the planning illustrations mean?

Any sample-size illustrations associated with these results are planning exercises based on the observed effect, not observed power and not the trial’s original design justification. The stated illustration assumptions are a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. General statistical principle: such calculations ask how many participants per arm might be needed under stated assumptions for a future study to detect a specified effect with a target power. They do not show the probability that this completed trial detected an effect, and they do not establish that the assumed effect is true or clinically important. The original sample-size justification and statistical plan are not reported in the registry record.

For a count endpoint, the choice of model can matter if the event counts vary more than a simple Poisson model assumes. General statistical principle: over-dispersion means the variability in counts exceeds the model’s expected variability; ignoring it can make uncertainty estimates too small. The registry labels the primary outcome as a count-other type but reports a percentage summary, and does not report a model or a formal comparison. It is therefore not possible to identify whether any count model or adjustment for over-dispersion was used.

Can the analysis choices be checked?

The registry records four outcome measures, one posted secondary outcome, and no posted analyses. General statistical principle: an analysis plan should specify the primary contrast, model, handling of missing outcomes, analysis population, and any adjustment for multiple testing. The record does not state these choices. The descriptive percentages can be read as posted, but the analysis methods behind them cannot be independently evaluated from the registry record. Recalculated estimates are not presented in the registry entries, and there is no stated discrepancy between a sponsor analysis and a recalculation.

10. Multiplicity, Missing Data and Analysis Populations

The registry identifies one primary endpoint and lists incidence rate of acute complications as a secondary outcome. It also records four outcome measures, but the posted results summary identifies only one secondary outcome. How the outcome measures relate to each other, which analyses were prespecified, and whether any additional outcomes were measured are not reported in the registry record.

Multiplicity arises when several outcomes, time points, or comparisons are tested. General statistical principle: testing many hypotheses can increase the chance of at least one apparently notable result, so a statistical plan may define a primary comparison or adjust for multiple testing. The registry record does not report whether multiplicity was addressed, whether outcomes were ordered hierarchically, or whether the secondary outcome was exploratory. No p-values are posted, so the effect of any multiplicity procedure cannot be assessed.

The record does not describe missing-data handling. It does not say whether participants with incomplete follow-up were excluded, how missing symptom assessments were treated, or whether sensitivity analyses were conducted. The primary outcome denominators are 87 for Radiofrequency Ablation and 89 for Laser Ablation, while registry enrollment is 200. The record does not explain the relationship among these figures, nor does it describe outcome availability for participants not represented in the primary results.

Analysis populations are also not reported in the registry record. It is not stated whether the primary analysis followed an intention-to-treat principle, used only participants who received the assigned procedure, or applied another rule. The registry records randomized allocation but does not report crossover, adherence, withdrawals, protocol deviations, or their handling. These omissions matter because exclusion or reassignment after randomization can affect the comparability that randomization is intended to provide.

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 0% reporting threshold.

The registry safety rows list 100 at risk and 0 affected for serious events in the Radiofrequency Ablation group, and 100 at risk and 0 affected in the Laser Ablation group. The rows for other events likewise list 100 at risk and 0 affected in each arm. These are the counts recorded in the safety summary. The record does not explain how these safety denominators were defined or how they relate to the primary-outcome denominators.

The registry lists no serious-event terms. Death figures are not reported in the registry record. A zero in an affected-count field means that the registry row records no affected participants for that category and denominator; it does not establish that the true risk is zero. General statistical principle: with finite observations, an observed zero count can still be compatible with a range of underlying event risks, and precision depends on the denominator and the method used to estimate uncertainty. No interval or formal comparison is reported for these safety figures.

The secondary outcome is incidence rate of acute complications, but no corresponding comparative analysis is posted. The listed safety counts should therefore be treated as limited descriptive entries, not as a complete account of all complications or as evidence that one procedure has a safer profile.

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

The registry reports an arm-level primary outcome of 79.3 without recurrent clinical symptoms for Radiofrequency Ablation and 77.5 for Laser Ablation. These figures describe the posted results for the stated endpoint and denominators. They do not include a confidence interval, p-value, or formal estimate of the difference between the treatment groups. The statistical precision and comparative uncertainty are therefore not established by the registry summary.

The result does not establish that either procedure is superior, equivalent, or noninferior. Those conclusions require a specified comparative analysis and, for equivalence or noninferiority, an appropriate design and margin. Neither a formal primary comparison nor such a margin is reported in the registry record. The result also does not establish that the procedures have identical effects just because the reported percentages are in a similar range; the record does not quantify uncertainty around their contrast.

Follow-up is relevant to interpretation. The endpoint is described as annual follow up up to 75 months, and mean follow-up and ranges are reported separately for the EVLA and RFA groups. The registry does not report the timing of recurrences, censoring, or adjustment for variation in follow-up. The arm percentages should not be treated as event rates per unit of time or assumed to summarize an identical observation period for every participant.

The registry also does not provide enough detail to assess baseline comparability, the handling of missing data, the analysis population, or the precise symptom-assessment process. These are not reasons to disregard the posted results; they are boundaries on what can be inferred from the record. The safety rows record zero affected participants in each listed category, but do not provide uncertainty estimates or a complete narrative of adverse events.

In general, a randomized comparison can inform decisions about relative effects when conduct, outcome definitions, analysis, and uncertainty are sufficiently documented. In this record, the available primary outcome is descriptive and the secondary complication outcome lacks a posted analysis. The result is therefore best understood as a limited registry summary of the outcomes reported, not as a definitive determination of comparative benefit or harm.

13. Why This Trial Matters Statistically

This trial is statistically notable as a randomized comparison of two procedures for the same clinical condition, with a long-term symptom outcome and an acute-complication outcome listed. Randomized allocation is a useful design feature for comparative inference because, when implemented and analyzed appropriately, it can reduce confounding by measured and unmeasured factors. The record identifies randomization, but does not provide enough implementation detail to evaluate that process fully.

The endpoint also highlights a common challenge in clinical trials: a clinical outcome may be reported as a percentage even when follow-up duration varies among participants. The record reports annual follow up up to 75 months and different mean follow-up durations and ranges across groups. General statistical principle: an analysis that accounts for event timing can answer a different question from a simple proportion. The registry does not state which analytical approach generated the posted percentages, underscoring the importance of clear endpoint and analysis descriptions.

Another statistical lesson is the distinction between descriptive arm results and a comparative estimate. The record gives a percentage for each arm, but no confidence interval or test for the difference. Readers need both the estimated contrast and its uncertainty to assess how informative a result is. Group-specific values alone cannot show whether a difference is precisely estimated or whether a range of materially different effects remains plausible.

The posted safety fields also illustrate why denominators and outcome definitions matter. The listed at-risk counts are not reconciled with the primary endpoint denominators, and no explanation of the safety population is reported. Transparent reporting of analysis populations, missing outcomes, and event ascertainment would help readers understand what each number represents. The trial’s registry entry is informative about its broad design and reported outcome values, while leaving important elements of statistical interpretation 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.

Several trial-specific gaps limit interpretation of the posted results. The registry does not report detailed eligibility criteria, participant characteristics, recruitment setting, baseline clinical status, or procedure-related characteristics. Without those details, it is difficult to judge how representative the enrolled participants were or whether the groups were comparable at baseline.

The record identifies randomization but does not describe sequence generation or allocation concealment. It records no masking, but does not explain whether outcome assessors were aware of treatment assignment or how recurrent symptoms were defined and assessed. The endpoint description does not specify which symptoms counted as recurrence, how recurrence was confirmed, or whether the same assessment procedures were used in both arms.

Follow-up is reported as annual up to 75 months, with group-specific mean durations and ranges, but the record does not give visit completion, loss to follow-up, recurrence timing, censoring, or missing-data information. It also does not explain the relation between enrollment and the primary-outcome denominators. The analysis population and handling of crossovers, withdrawals, or protocol deviations are not reported in the registry record.

The record does not provide a statistical analysis plan, the primary treatment contrast, confidence intervals, p-values, or a time-to-event analysis. It does not report the original sample-size justification or whether any interim analyses occurred. The safety summary gives at-risk and affected counts without explaining the denominator definition, and death figures are not reported. The secondary complication outcome is listed without a posted comparative result.

These limitations concern what can be learned from the registry record; they do not establish that a particular method was or was not used. They mean that readers cannot fully assess precision, missingness, outcome ascertainment, or the analysis choices underlying the reported percentages from this record alone.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Radiofrequency Ablation vs Laser Ablation of the Incompetent Greater Saphenous Vein — NCT02236338.
• Registry record last updated 2018-05-14; status last verified 2018-04.
• Results first posted 2018-05-14.
• 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 record describes a completed Phase 4, prospective randomized parallel trial sponsored by Virginia Commonwealth University. It compared radiofrequency ablation using a ClosureFAST radiofrequency catheter with laser ablation using an EVLT 980nm diode laser system for an incompetent greater saphenous vein in chronic venous insufficiency. Masking is recorded as none.

The primary outcome was the percentage without recurrent clinical symptoms after treatment, with annual follow up up to 75 months. The registry reports 79.3 for Radiofrequency Ablation, with 87 participants, and 77.5 for Laser Ablation, with 89 participants. Mean long-term follow-up was 42 months in the RFA group and 44 months in the EVLA group. Incidence rate of acute complications is listed as a secondary outcome, but no comparative analysis is posted. The record does not report uncertainty estimates or the statistical plan needed to assess the precision of the primary comparison.