EPIC Nitinol Stent System in the Treatment of Atherosclerotic Lesions in Iliac Arteries: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for EPIC Nitinol Stent System in the Treatment of Atherosclerotic Lesions in Iliac Arteries (NCT00896337), a na phase 3 study. The primary outcome is Device- and/or Procedure-related Major Adverse Events (MAE).

2. Clinical Question

3. Trial Design

ORION is registered as a phase 3, single-group study of the Epic™ Nitinol Stent System for atherosclerotic lesions in iliac arteries. The condition listed is iliac artery stenosis, and the registry lists enrollment of 125. The record describes one arm, ORION, in which enrolled participants meeting the inclusion criteria were to undergo iliac artery stenting with the device.

The record does not describe a randomized allocation or a separate control arm. Allocation is listed as NA, the model as single group, and masking as none. These features matter when interpreting the study: its design does not permit a direct randomized comparison between the stent and another treatment or control condition. Any observed event rate would describe the study group, rather than an estimated difference between assigned groups.

The listed interventions include the stent system, anti-platelet therapy, and anti-coagulation therapy. The record does not specify treatment schedules or further details about how the drug therapies were used. The brief summary describes the study aim as evaluating acceptable performance at 9 months. The primary endpoint timeframe is also 9 Months.

The registry lists the study as completed, with a start date of 2009-05 and primary completion date of 2011-09. The primary endpoint description states that analysis was intention to treat and that all participants were to undergo clinical follow-up for the information needed to assess the endpoint; it also says 7 participants were not evaluable. The record does not report additional design details such as eligibility criteria, the planned acceptance threshold, or the rationale for the enrollment target.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Analysis was intention to treat; all participants in the study were to undergo clinical follow up to provide the information needed for this endpoint; 7 participants were not evaluable.

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 Device- and/or Procedure-related Major Adverse Events (MAE), measured over 9 Months.

The primary endpoint is the percentage of participants with device- and/or procedure-related major adverse events (MAE) at 9 Months. The registry defines MAE as any device-related or index procedure-related death within 30 days, myocardial infarction during the index hospitalization, target vessel revascularization through 9 months, or amputation of the index limb through 9 months. It is therefore a composite endpoint: a participant can meet it through any one of the listed event types.

A composite can capture several clinically important kinds of harm in one measure and can provide a broad summary of events associated with the device or procedure. Its interpretation depends on the definition and on which component events occur. The registry record does not report the component-specific results, so it is not possible to tell from the posted information which event types contributed to the endpoint.

The measure is a participant percentage, not a measure of the total number of events. The record describes an intention-to-treat analysis and says all participants were to receive clinical follow-up, while noting that 7 were not evaluable. It does not report the observed numerator, percentage, confidence interval, or test result for this endpoint. Nor does it give an acceptance threshold against which the stated aim of acceptable performance could be judged.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a binary participant-level primary outcome: whether a participant experienced at least one event meeting the MAE definition during the specified period. The reported unit is percentage of participants. In general, a binary outcome classifies each participant into one of two categories for the endpoint, such as event or no event. A percentage expresses the share of the analysis group in the event category. The registry record does not report the observed number of participants meeting this endpoint or its percentage.

What does a confidence interval convey?

In general, a confidence interval gives a range of values compatible with the data under the assumptions of the statistical method used. For an event percentage, it helps communicate uncertainty around the estimated rate: a narrower interval indicates greater precision, while a wider interval indicates less precision. It does not guarantee that the true rate lies within the interval, nor does it correct limitations in the study design or data collection. No confidence interval for the primary endpoint is reported in the registry record, so its precision cannot be evaluated from the posted results.

What would a hypothesis test answer?

In general, a hypothesis test evaluates how compatible data are with a specified null hypothesis under a chosen statistical model. A p-value is not the probability that the null hypothesis is true and does not measure the size or clinical importance of an effect. Its interpretation depends on the analysis plan, endpoint, and assumptions. The registry record does not report a primary-endpoint hypothesis test or p-value. It also does not report a statistical analysis plan specifying the relevant hypothesis or decision rule.

Why does the single-group design matter?

A single-group study can describe the frequency of outcomes in the participants followed, but it does not create a randomized counterfactual group for comparison. In general, random allocation can help balance known and unknown influences across treatment groups. Without a randomized comparator, a difference from an external reference or an assumed rate would not have the same protection against bias as a randomized comparison. The registry record does not list a control arm, a comparator rate, or an acceptance threshold for the stated performance aim.

The study’s primary endpoint is composite. In general, a composite can increase the breadth of an outcome measure by counting several event types, but interpretation requires attention to the definition and to component results. An aggregate percentage alone would not show which component occurred, whether one component drove the result, or whether components had similar clinical importance. The registry record defines the components but does not report their endpoint-specific counts.

How should the non-evaluable participants be understood?

The endpoint description says the analysis was intention to treat and that all participants were to undergo clinical follow-up, while also stating that 7 participants were not evaluable. These statements identify an analysis intention and an evaluability issue; they do not explain the actual handling of those participants. In general, missing or unavailable outcome data can affect an estimate if the participants’ outcomes differ from those observed. Methods such as assumptions about missing outcomes or sensitivity analyses can help assess robustness, but the registry record does not report whether such methods were used.

The registry lists one analysis. That count does not establish which statistical procedure was used, whether there were planned interim analyses, or how the endpoint result was assessed. The statistical plan and interim-analysis information are not reported in the registry record. They should not be inferred from the endpoint format or the study’s phase designation.

General statistical interpretation should distinguish estimates from design assumptions. A sample-size planning illustration, when available, is a hypothetical calculation under stated assumptions; it is not an observed outcome or evidence that the study had a particular probability of success. The registry record’s stated enrollment is 125, but it does not report the rationale for that enrollment target or a sample-size justification. The primary endpoint result is also absent, so no recalculation based on the observed endpoint can be interpreted from this record.

Finally, the listed serious adverse event counts are descriptive safety information, not an analysis of the primary composite endpoint. They do not supply a randomized comparison, and the listed event terms may represent different types of events from the specifically defined MAE components. General statistical practice is to keep outcome definitions, analysis populations, follow-up periods, and denominators distinct when interpreting results.

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("Epic Stent")
n      <- c(118)
events <- c(4)
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  Epic Stent  118  4  3.4  0.9  8.5  1.3  8.4  1.4  8.4

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists 64 outcome measures and one analysis, but does not report how multiplicity was handled. In general, testing many outcomes can increase the chance of at least one apparently notable result occurring by chance, depending on the analysis plan and the relationships among outcomes. A prespecified primary endpoint can help focus interpretation, but the registry record does not provide a statistical plan describing testing order, adjustment methods, or decision rules. No multiplicity adjustment should be assumed.

The record identifies the primary endpoint and says the analysis was intention to treat. It also says all participants were to undergo follow-up for this endpoint, while noting that 7 were not evaluable. The registry does not report the number included in the endpoint calculation, how those participants were treated in the analysis, or whether imputation or sensitivity analyses were used. The missing-data handling is therefore not reported in the registry record.

In general, intention-to-treat analysis refers to analyzing participants according to their assigned study group, regardless of subsequent treatment changes. In a single-group study, the phrase does not create a control comparison. The record does not explain how the stated intention-to-treat approach related to the non-evaluable participants or provide enough detail to reconstruct the analysis population.

The record does not describe interim analyses, a multiplicity strategy, or a complete statistical analysis plan. Those details are not reported in the registry record and should not be inferred from the listed number of analyses or outcomes.

12. 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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: angina pectoris (5.6%), atrial fibrillation (5.6%), pneumonia (4.8%), iliac artery stenosis (4.8%), chronic obstructive pulmonary disease (4.0%).

The adverse-event summary lists 77 of 125 participants at risk as affected by serious adverse events, and 63 of 125 as affected by other adverse events. These are descriptive entries for the ORION group, not comparisons between treatment arms. The registry also lists Angina Pectoris and Atrial Fibrillation at 5.6% each; Pneumonia and Iliac Artery Stenosis at 4.8% each; and Chronic Obstructive Pulmonary Disease and Intermittent Claudication at 4.0% each among the top serious-event terms.

These serious-event entries should be kept distinct from the primary MAE endpoint. The MAE definition is restricted to specified device- or procedure-related events within its stated time windows. The serious adverse event summary is not identified as a count of participants meeting that composite definition, and it does not provide component-level MAE results. The record does not report a death count in this summary.

Because the study has one group and no randomized comparator, these figures describe recorded events in the study group rather than a comparative safety estimate. The registry does not provide further details on event timing, attribution, or how the listed terms relate to individual participants.

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

The registry record establishes that ORION was a completed, phase 3, single-group study of the Epic™ Nitinol Stent System in participants with iliac artery stenosis. It describes an intended 9-month assessment of device- and/or procedure-related MAE, defines the components of that endpoint, and records enrollment of 125. It also reports serious adverse event summaries for the ORION group.

However, the primary endpoint result is not reported in the registry record. The observed number and percentage of participants with MAE, the endpoint confidence interval, and any test result are absent. The record also does not give an acceptance threshold, so the stated aim of determining acceptable performance cannot be evaluated from the posted endpoint information. The absence of a reported result is not evidence that no events occurred.

The single-group design is another important boundary on interpretation. The study description does not include a randomized control arm, so the record cannot provide a randomized comparison of outcomes against another treatment. The adverse-event counts describe the study group and should not be interpreted as a treatment effect or as proof of causation.

The MAE endpoint combines several event types, but component-specific results are not reported. The separate serious adverse event summary cannot substitute for those results because it is not the same endpoint definition. The record also notes 7 participants were not evaluable, without reporting how their outcomes were handled in the primary analysis.

Accordingly, the record supports a description of the study’s design, intended endpoint, and selected safety information, but not a quantitative conclusion about primary endpoint performance or a comparative treatment effect.

14. Why This Trial Matters Statistically

This study is statistically instructive because its stated question concerns acceptable performance, while the registry record does not report the primary endpoint result or the acceptance threshold. A performance claim depends not only on the endpoint definition but also on the observed estimate, its uncertainty, and the criterion used to judge it. Without those elements, the stated aim cannot be assessed using the posted record.

The single-group structure illustrates the difference between estimating an event frequency and estimating a comparative treatment effect. A group-specific percentage can describe what occurred among participants followed, but a randomized comparator supports a different question: how outcomes differ under alternative assigned conditions. The registry lists no such control arm, so interpretation must remain descriptive rather than comparative.

The composite endpoint also illustrates why outcome definitions matter. It combines death, myocardial infarction, target vessel revascularization, and amputation of the index limb, with different event windows. A composite can summarize a range of outcomes, but the overall result alone would not explain which events occurred. The registry does not report component-specific primary endpoint results.

Finally, the record identifies an intention-to-treat analysis and 7 participants who were not evaluable, but does not explain how they were handled. This highlights the importance of reporting analysis populations and missing-data methods alongside an endpoint estimate. A clear result needs enough information for readers to understand both what was counted and how uncertainty was quantified. Those details are not reported for the primary outcome 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 main trial-specific limitation for interpretation is the absence of a reported primary endpoint result. The registry describes MAE and its timeframe but provides no observed count or percentage, confidence interval, or hypothesis-test result. It also does not state an acceptance threshold, despite describing the aim as determining acceptable performance.

The design is single group, with allocation listed as NA and masking as none. No randomized control group is described. Consequently, the registry record does not support a randomized between-group estimate, and descriptive event information cannot by itself establish that outcomes were caused by the device or procedure.

The endpoint is a composite of several event types, but the record does not provide primary-endpoint component counts. Its definition includes different time windows, which should be considered when interpreting any aggregate result. The separate adverse-event summary does not resolve this limitation because it is not reported as the primary MAE outcome.

The endpoint description notes that 7 participants were not evaluable, while stating that all participants were to undergo follow-up and that the analysis was intention to treat. The record does not explain how non-evaluable participants were handled or report sensitivity analyses. The statistical plan, missing-data approach, multiplicity handling, interim-analysis information, and sample-size justification are not reported in the registry record.

Finally, the adverse-event summary does not report a death count and does not provide further detail on timing or attribution. These gaps restrict interpretation of both the endpoint and safety information available in the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: EPIC Nitinol Stent System in the Treatment of Atherosclerotic Lesions in Iliac Arteries — NCT00896337.
• Registry record last updated 2015-05-07; status last verified 2015-04.
• Results first posted 2012-07-03.
• 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

ORION is a completed phase 3, single-group study of the Epic™ Nitinol Stent System for iliac artery stenosis. The registry lists enrollment of 125, a start date of 2009-05, and a primary completion date of 2011-09. The primary endpoint is the percentage of participants with device- and/or procedure-related MAE at 9 Months.

The registry defines MAE through specified death, myocardial infarction, target vessel revascularization, and amputation events. It describes an intention-to-treat analysis and notes that 7 participants were not evaluable. The primary endpoint result is not reported in the registry record. The record also lists serious adverse event summaries for the ORION group, but no randomized comparator is described.