JetStream Atherectomy for the Treatment of In-stent Restenosis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for JetStream Atherectomy for the Treatment of In-stent Restenosis (NCT02730234), a na na study. The primary outcome is Percentage of Participants With Target Lesion Revascularization (TLR).

2. Clinical Question

The clinical question concerns retreatment of the treated lesion after a procedure for femoropopliteal in-stent restenosis. Its interpretation depends on both the endpoint definition and the historical nature of the comparator. The study observed outcomes among participants receiving the combined procedure; it did not randomly assign participants to that procedure or to balloon angioplasty alone. Consequently, any comparison with the historical data would not have the protection against group differences that random allocation can provide.

The registry describes a prospective, multicenter study of the investigational use of the device in people with claudication or limb ischemia. It does not report a concurrent control group, a primary outcome estimate, or a statistical comparison result. The record therefore establishes the question the investigators intended to address, but does not report enough primary-outcome information to determine the observed six-month TLR frequency or the precision of an estimate.

3. Trial Design

NCT02730234, titled “JetStream Atherectomy for the Treatment of In-stent Restenosis,” is listed as completed. The registry records a prospective, multicenter, single-arm study with enrollment of 60 participants. The start is listed as 2016-04, and primary completion as 2020-02-04. The phase is recorded as NA, allocation as NA, and masking as NONE. The sponsor is Midwest Cardiovascular Research Foundation.

All participants in the described intervention group received JetStream atherectomy with the JetStream XC device followed by balloon angioplasty. The target condition was femoropopliteal in-stent restenosis. Eligible clinical circumstances described in the summary included claudication or limb ischemia, Rutherford clinical category 2-4, and lesion length of at least 4 cm. The record does not provide further eligibility criteria in the registry record reported for this study.

The study’s intended comparison was with historic plain old balloon angioplasty data derived from a meta-analysis of 3 published randomized trials. This was not a randomized, concurrent control group within NCT02730234. Differences in how participants were selected, treated, followed, or assessed across the study and historic data could affect a comparison; the registry record does not describe how such differences were addressed.

The primary endpoint was the percentage of participants with target lesion revascularization at 6 months. The endpoint definition includes intra-procedural bailout stenting of the index lesion as meeting the TLR endpoint. The record describes an intention-to-treat analysis, while also stating that 4 participants who died before a TLR occurred were excluded from the six-month analysis. Five people died at 6 months; one had TLR before death and was counted in the TLR analysis. The registry record does not report the primary endpoint result or a detailed statistical analysis plan.

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: 5 people died at 6 months. 1 patient had TLR before death and was counted in the TLR analysis. 4 patients were not analyzed at 6 months as they were dead before a TLR occurred (censored). So these 4 patients were excluded from the analysis at 6 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 With Target Lesion Revascularization (TLR), measured over 6 months.

The primary endpoint was the percentage of participants with target lesion revascularization (TLR) at 6 months. TLR was defined as retreatment of the index lesion, extending 1 cm proximal and distal to the lesion. For the primary endpoint, intra-procedural bailout stenting of the index lesion was also counted as meeting the TLR endpoint. The registry describes the endpoint as a count of participants and labels the analysis intention-to-treat.

TLR is an event-based outcome: it records whether a participant experienced a specified retreatment event within the follow-up period. Such an endpoint can capture the need for additional treatment at the lesion site, rather than only a measurement made during the initial procedure. The definition matters because decisions about what qualifies as an event determine which participants are counted. Including bailout stenting means that the primary endpoint encompasses an event during the original procedure as well as later retreatment, according to the registry’s definition.

The endpoint’s six-month time frame sets the period over which the event is assessed. The record notes that 5 people died at 6 months. One had TLR before death and was counted in the TLR analysis; 4 people who died before TLR occurred were excluded from the six-month analysis. The primary endpoint result itself is not reported in the registry record. Without the number of participants meeting the definition and the corresponding analysis denominator, the event frequency and its statistical precision cannot be described.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a prospective, multicenter, single-group study. This design means outcomes were collected in participants who received the JetStream XC device followed by balloon angioplasty, without a concurrently randomized comparison group in the study. The intended comparison with plain old balloon angioplasty relied on historic data from a meta-analysis of 3 published randomized trials. The registry does not report the details of that meta-analysis or the methods used to make the historical data comparable with the study participants.

What does a single-group design show?

In general, a single-group study can describe the frequency of an outcome after an intervention in the participants enrolled. By itself, it cannot separate the intervention’s effect from other influences on the outcome. A concurrent randomized control group helps balance, on average, factors that might affect outcomes, while a historical comparison can be affected by differences between the separate data sources. This is a general design consideration, not a claim about a particular difference in this study. The registry does not report which potential differences were assessed or controlled.

How should the binary endpoint be understood?

The primary outcome is binary at the participant level: a participant either meets the registry’s TLR definition during the stated follow-up or does not. The endpoint is reported as a count of participants, with the title describing a percentage. In general, a binary event rate is interpreted alongside its denominator. A count without the number assessed, or a percentage without an account of who was included, can be difficult to interpret. The primary outcome count and percentage are not reported in the registry record.

The definition combines retreatment of the index lesion with intra-procedural bailout stenting as an event. It also specifies the treated lesion’s boundaries as extending 1 cm proximal and distal to the lesion. These operational details are part of the outcome measurement: changing them could change which observations qualify as TLR. The registry record additionally lists TLR without bailout stenting as a secondary outcome, indicating that the bailout component can be distinguished in outcome definitions, though its results are not reported in the registry record.

What does a confidence interval express?

In general, a confidence interval describes the statistical uncertainty around an estimated quantity, such as an event rate or a difference between groups. A narrower interval indicates greater precision under the assumptions of the analysis; a wider interval indicates less precision. It does not account automatically for every source of uncertainty, such as bias from a nonrandomized historical comparison or differences in outcome measurement. No primary TLR estimate or confidence interval is reported in the registry record, so its precision cannot be assessed.

Why does over-dispersion matter?

In general, over-dispersion occurs when outcome variability is greater than a statistical model expects. If a model assumes less variability than the data contain, its uncertainty estimates may be too small. This concept is more commonly relevant to count outcomes than to a simple participant-level binary endpoint. No over-dispersion assessment or related model is reported in the registry record, and the registry entries do not indicate that such a method was used for the primary endpoint.

What can planning calculations say?

In general, a sample-size calculation describes a planning scenario under specified assumptions; it is not a measure of observed power after a study has finished. The planning illustration associated with this study is described as using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It considers an effect to detect as a stated fraction of the observed effect. The stated assumptions describe an illustration, not the trial’s own design rationale. The record does not report the protocol’s sample-size justification, and no numerical planning values are available in the registry entries described for this analysis.

Because the actual trial was single-group, an equal-allocation, two-arm scenario in a planning illustration should not be read as a description of the study’s enrollment or treatment assignment. It is not evidence that the trial had a particular probability of detecting an effect. Nor can a planning scenario replace an estimate and interval based on observed results. Sample sizes generated under assumptions remain hypothetical planning quantities, not observed power.

What can a significance test establish?

In general, a significance test evaluates how compatible data are with a specified null hypothesis under the assumptions of the test. A p-value is not the probability that a treatment works, and it does not measure the size or clinical importance of an effect. Interpretation depends on the test, endpoint, analysis population, and design. The registry record reports 0 analyses and does not report a primary test or p-value. No conclusion about statistical significance can be drawn from the endpoint description alone.

The registry lists 16 outcome measures, including secondary outcomes such as procedural success, clinical patency, change in Walking Impairment Questionnaire score, and Rutherford clinical category improvement. The number of listed outcomes does not reveal whether analyses were prespecified, how endpoints were prioritized, or whether any adjustment was made for multiple testing. Those statistical-plan details are not reported in the registry record.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("JetStream XC With Balloon Angioplasty")
n      <- c(56)
events <- c(12)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  JetStream XC With Balloon Angioplasty  56  12  21.4  11.6  34.4  12.7  33.8  12.7  33.9

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 16 outcome measures and several secondary outcomes, including device outcome, procedural success, TLR with and without bailout stenting, clinical patency, change in Walking Impairment Questionnaire score, and Rutherford clinical category improvement. A study that examines multiple outcomes may face a multiplicity issue: in general, the more statistical tests performed, the greater the chance of at least one apparently unusual result under a collection of null hypotheses. Strategies such as defining a primary endpoint in advance or adjusting for multiple comparisons can address different aspects of this issue. The registry record does not report a testing hierarchy, multiplicity adjustment, or detailed statistical analysis plan. It also reports 0 analyses.

The primary endpoint description identifies an intention-to-treat analysis, but also states that 4 participants who died before TLR occurred were censored and excluded from the six-month analysis. One participant with TLR before death was counted. The record says 5 people died at 6 months. These details indicate that not all enrolled participants were included in the described endpoint analysis, but do not provide the full denominator or a complete account of missing outcome data.

In general, missing-data handling can affect an estimate when the availability of an outcome is related to participants’ characteristics or outcomes. Censoring is a specific way to represent that follow-up ends before an event is observed; it does not establish what would have happened afterward. The record does not report an imputation method, sensitivity analysis, or additional assumptions about the excluded participants. It also does not describe analysis populations for the secondary outcomes. These aspects of multiplicity and missing-data handling are not reported in the registry record.

12. 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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: target lesion revascularization with bailout stenting (35.0%), target lesion revascularization without bailout stenting (18.3%), distal embolization (13.3%), major bleeding (1.7%), nonfatal myocardial infarction (1.7%).

The intervention group includes 60 participants at risk for serious adverse events and 60 at risk for other adverse events. The registry records 21 participants with serious adverse events, 15 with other adverse events, and 8 deaths. These are separate safety summaries; the record does not establish that the categories are mutually exclusive, so they should not be added together or treated as distinct groups of people.

The listed serious adverse-event terms include target lesion revascularization with bailout stenting (35.0%), target lesion revascularization without bailout stenting (18.3%), and distal embolization (13.3%). Major bleeding and nonfatal myocardial infarction are each listed at 1.7%, and unplanned major amputation at 0.0%. The term-specific percentages describe the registry’s posted categories; they do not on their own explain how events were attributed, whether a participant could contribute to more than one category, or how the categories relate to the overall count.

Safety summaries describe events recorded in the study, but a single-group record cannot establish a comparative excess or reduction in risk. The registry entries do not report a control-group safety result or provide further information on event attribution. The 8 deaths listed in the safety record should also be distinguished from the primary endpoint description, which specifically discusses 5 people who died at 6 months and their treatment in the TLR analysis. The record does not explain the relationship between those two death counts.

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

The record establishes that a prospective, multicenter, single-arm study enrolled 60 participants with femoropopliteal in-stent restenosis and evaluated JetStream atherectomy followed by balloon angioplasty. It also defines the primary endpoint as TLR at 6 months, including intra-procedural bailout stenting. Those details clarify what the study set out to examine and what would count as an event.

The record does not report the primary TLR result, an estimate of its precision, or a statistical test. Therefore, the study’s observed primary outcome cannot be quantified from the information described in the registry record. The design and endpoint definition alone do not show whether an event was more or less frequent than in historic balloon-angioplasty data, nor do they establish the size or certainty of a difference.

The planned historical reference also limits what a comparison could establish. This trial did not randomly assign participants to JetStream plus balloon angioplasty or balloon angioplasty alone. In general, differences between a study group and historic data can reflect factors other than the procedure being compared. The registry entries do not report enough detail to assess whether those data sources were comparable or how any differences were handled.

Safety counts are available, including serious and other adverse events and deaths, but these are observations in the intervention group rather than a randomized comparative safety analysis. Event counts and listed terms do not by themselves establish causation. The registry also describes deaths and exclusions in the primary endpoint analysis; that accounting should be considered when interpreting any future report of the six-month endpoint.

Accordingly, the trial record contributes information about the study design, intended comparison, outcome definitions, and selected safety observations. It does not, on its own, support a numerical conclusion about the primary endpoint or a causal conclusion about treatment effects. Any stronger assessment would require the unreported primary outcome result, its uncertainty, and adequate information about the historical comparison and analysis methods.

14. Why This Trial Matters Statistically

This study is statistically informative as an example of the distinction between an outcome question and the evidence available to answer it. The investigators posed a clear six-month question about TLR and described an operational definition that includes bailout stenting. Yet the registry entries do not report the primary result. Without the event count, analysis denominator, and an estimate of uncertainty, readers cannot assess the observed rate or its precision from this record.

The single-group design also makes the comparator issue central. The intended benchmark came from historic plain old balloon angioplasty data, not from participants randomized within this study. Such a comparison can be useful for framing a question, but it does not have the same design basis as a concurrent randomized comparison. Assessing it would require sufficient information about the historic data, outcome definitions, participant characteristics, and analytical approach; these details are not reported in the registry entries described.

The record also illustrates why analysis populations and endpoint definitions matter. The primary description calls the analysis intention-to-treat while stating that 4 people who died before TLR occurred were excluded from the six-month analysis. It also specifies that a TLR event before death was counted. These details influence the interpretation of the endpoint denominator and should accompany any reported event estimate.

Finally, the registry identifies multiple outcomes and safety categories without reporting a statistical analysis plan or outcome tests. This makes it important to distinguish what was measured from what was analyzed and reported. The record offers useful design and safety context, but the absence of the primary outcome result means its central efficacy question remains quantitatively unanswered in the registry record.

15. 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 key limitation for interpreting this trial record is that the primary six-month TLR result is not reported in the registry entries. The record gives the endpoint definition and selected information about deaths, but not the number of participants meeting the endpoint, the corresponding percentage, or an interval expressing uncertainty. The primary outcome therefore cannot be quantitatively assessed from the available record.

The study is single-arm, while the intended comparator is historic data from a meta-analysis of 3 published randomized trials. The historic group was not a concurrent randomized control arm in this study. The registry entries do not report the historical outcome values, the methods used to align or adjust the data, or an assessment of comparability. As a result, the strength and interpretation of any historical contrast cannot be evaluated from these details.

The endpoint population description also raises an interpretation issue. The primary endpoint is labelled intention-to-treat, but 4 participants who died before TLR occurred are described as censored and excluded from the six-month analysis. The record does not report the full analysis denominator, how other missing outcomes were handled, or whether sensitivity analyses were conducted. The relationship between the 8 deaths in the safety summary and the 5 deaths described for the six-month endpoint is not explained.

Other statistical details are absent: the registry entries do not report a sample-size justification, a detailed analysis plan, multiplicity handling, or primary endpoint test. The study lists 16 outcome measures, but the planned hierarchy and reporting approach are not described. These limitations do not establish that a particular analysis was inappropriate; they identify information not reported in the registry record and needed for a fuller assessment.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: JetStream Atherectomy for the Treatment of In-stent Restenosis — NCT02730234.
• Registry record last updated 2021-08-11; status last verified 2020-10.
• Results first posted 2021-01-29.
• 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.

19. Record Summary

NCT02730234 is a completed, prospective, multicenter, single-group study of JetStream XC atherectomy followed by balloon angioplasty for femoropopliteal in-stent restenosis. The record lists enrollment of 60 participants, a start of 2016-04, and primary completion on 2020-02-04. The study’s intended comparison was with historic plain old balloon angioplasty data derived from a meta-analysis of 3 published randomized trials, rather than a concurrent randomized control group.

The primary endpoint was TLR at 6 months, with intra-procedural bailout stenting included in its definition. The registry describes 5 deaths at 6 months, including 1 participant with TLR before death and 4 excluded from the endpoint analysis after dying before TLR occurred. The primary endpoint result and its statistical uncertainty are not reported in the registry record. Safety counts include 21 participants with serious adverse events, 15 with other adverse events, and 8 deaths. The record lists 16 outcome measures and 0 analyses.