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 ELUVIA™ Drug-eluting Stent Versus Zilver® PTX® Stent (NCT02574481), a randomized na study. The primary outcome is Percentage of Participants With Major Adverse Events (MAEs).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02574481 |
| Phase | NA |
| Condition | Atherosclerosis of Native Arteries of the Extremities |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Single |
| Enrollment | 524 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Boston Scientific Corporation |
| Results posted | Yes |
2. Clinical Question
Population
Participants with atherosclerosis of native arteries of the extremities undergoing treatment for lesions in the superficial femoral artery and/or proximal popliteal artery. The stated primary objective covers lesions up to 140 mm in length; a long lesion substudy covers lesions longer than 140 mm and no more than 190 mm. Further eligibility details are not reported in the registry record.
Intervention
Percutaneous implantation of the ELUVIA drug-eluting vascular stent system. The registry describes treatment in the superficial femoral artery and/or proximal popliteal artery.
Comparator
Percutaneous implantation of the Zilver PTX stent in the superficial femoral artery and/or proximal popliteal artery.
Primary question
How does the percentage of participants with a major adverse event through 12 months compare between the ELUVIA and Zilver PTX groups? The registry record defines the endpoint but does not present a single comparison for interpretation.
The trial is registered as randomized and uses a parallel design. Its stated primary objective is to evaluate the safety and effectiveness of ELUVIA for the specified artery lesions, with Zilver PTX as the comparator. The registry lists an enrollment of 524, but does not report the number assigned to each primary comparison group in the registry record for this analysis. It also does not report the eligibility criteria needed to describe the study population in greater detail.
The primary endpoint combines several clinical events rather than describing one event alone. It includes all-cause death through 1 month, target-limb major amputation through 12 months, and/or target lesion revascularization through 12 months. The registry record does not provide one effect estimate or a complete comparison across the endpoint’s categories or time points. Consequently, the stated question can be described, but the relative results cannot be characterized from this record.
3. Trial Design
This is a randomized, single-masked, parallel-group trial of ELUVIA stent implantation versus Zilver PTX stent implantation. The registry lists an enrollment of 524 and records the trial as completed. It gives a start date of 2015-12 and a primary completion date of 2017-12-28. The phase is listed as NA. Further details about the randomization process, what was masked, and how masking was maintained are not reported in the registry record.
The study concerns atherosclerosis of native arteries of the extremities. The brief description identifies treatment of superficial femoral artery and/or proximal popliteal artery lesions. The primary objective covers lesions up to 140 mm in length. A long lesion substudy concerns lesions longer than 140 mm and no more than 190 mm in length. The registry also names a PK substudy, but its purpose and relationship to the primary comparison are not reported in the registry record.
The intervention descriptions identify percutaneous stent placement in the superficial femoral artery and/or proximal popliteal artery for both treatment groups. The record lists secondary outcomes including clinical events, sustained clinical improvement, hemodynamic improvement, Walking Impairment Questionnaire scores, and distance and speed on the 6-Minute Walk Test. It records 11 outcome measures and 2 analyses, but the details needed to understand every analysis are not reported in the registry record.
Randomization is a design method intended to make treatment groups comparable on average with respect to factors that could affect outcomes. That is a general statistical principle, not a guarantee that every measured or unmeasured characteristic will be balanced in a particular trial. The registry does not give details about allocation concealment, stratification, or the method used to generate assignments. It also does not describe the masking role or identify which groups of study personnel were masked.
The registry’s enrollment figure describes the trial’s registered enrollment; it should not be treated as a substitute for outcome-specific denominators or group-specific analysis populations. Those denominators and populations are not reported in the registry record for the primary endpoint in the registry record.
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.
Before assignment: A total of 524 subjects have been enrolled in the IMPERIAL trial, including 465 subjects in the RCT, 50 subjects in the LL substudy and 13 subjects in the PK substudy. There were 4 subjects enrolled in both the PK and Long Lesion substudy.
Overall Study
| Stage | ELUVIA Stent Implantation | Zilver PTX Stent Implantation | Long Lesion Substudy | PK Substudy |
|---|---|---|---|---|
| STARTED | 309 | 156 | 50 | 13 |
| COMPLETED | 195 | 102 | 25 | 8 |
| NOT COMPLETED | 114 | 54 | 25 | 5 |
Reasons for not completing this period:
| Reason | ELUVIA Stent Implantation | Zilver PTX Stent Implantation | Long Lesion Substudy | PK Substudy |
|---|---|---|---|---|
| Withdrawal by Subject | 29 | 15 | 4 | 1 |
| Adverse Event | 5 | 1 | 1 | 0 |
| Visit Missed | 15 | 7 | 5 | 0 |
| Other | 7 | 2 | 0 | 0 |
| Death | 48 | 26 | 12 | 4 |
| Physician Decision | 5 | 2 | 0 | 0 |
| Lost to Follow-up | 5 | 1 | 3 | 0 |
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 | ELUVIA Stent Implantation | Zilver PTX Stent Implantation | Long Lesion Substudy | PK Substudy | Total |
|---|---|---|---|---|---|---|
| Participants analysed | 309 | 156 | 50 | 13 | 528 | |
| Age, Continuous | years | 68.5 (SD 9.5) | 67.8 (SD 9.4) | 68.2 (SD 8.9) | 66.4 (SD 6.1) | 68.3 (SD 9.3) |
| Sex: Female, Male: Female | Participants | 105 | 52 | 18 | 3 | 178 |
| Sex: Female, Male: Male | Participants | 204 | 104 | 32 | 10 | 350 |
| Race/Ethnicity, Customized: Hispanic or Latino | Participants | 18 | 6 | 3 | 0 | 27 |
| Race/Ethnicity, Customized: Caucasian | Participants | 205 | 108 | 30 | 13 | 356 |
| Race/Ethnicity, Customized: Asian | Participants | 1 | 0 | 0 | 0 | 1 |
| Race/Ethnicity, Customized: Japanese | Participants | 56 | 28 | 11 | 0 | 95 |
| Race/Ethnicity, Customized: Black, or African Heritage | Participants | 21 | 11 | 6 | 0 | 38 |
| Race/Ethnicity, Customized: Native Hawaiian or Pacific Islander | Participants | 1 | 0 | 0 | 0 | 1 |
| Race/Ethnicity, Customized: American Indian or Alaska Native | Participants | 2 | 2 | 0 | 0 | 4 |
| Race/Ethnicity, Customized: Other | Participants | 3 | 1 | 0 | 0 | 4 |
| Race/Ethnicity, Customized: Not Disclosed | Participants | 2 | 0 | 0 | 0 | 2 |
| Region of Enrollment: New Zealand | participants | 9 | 5 | 1 | 0 | 15 |
| Region of Enrollment: Canada | participants | 17 | 7 | 0 | 0 | 24 |
| Region of Enrollment: Europe | participants | 89 | 44 | 4 | 0 | 137 |
| Region of Enrollment: United States | participants | 138 | 72 | 34 | 13 | 257 |
| Region of Enrollment: Japan | participants | 56 | 28 | 11 | 0 | 95 |
| History of Smoking (Current) | Participants | 109 | 63 | 16 | 3 | 191 |
| History of Smoking (Previous) | Participants | 157 | 68 | 26 | 10 | 261 |
| History of Smoking (Never) | Participants | 42 | 22 | 8 | 0 | 72 |
| History of Smoking (Unknown) | Participants | 1 | 3 | 0 | 0 | 4 |
| Current Diabetes Mellitus | Participants | 129 | 68 | 20 | 7 | 224 |
| History of Hyperlipidemia requiring medication | Participants | 235 | 118 | 41 | 12 | 406 |
| History of Hypertension requiring medication | Participants | 254 | 133 | 46 | 12 | 445 |
| History of Chronic Obstructive Pulmonary Disease | Participants | 48 | 28 | 9 | 2 | 87 |
| History of Coronary Artery Disease (CAD) | Participants | 156 | 70 | 28 | 7 | 261 |
| History of Myocardial Infarction (MI) | Participants | 60 | 27 | 9 | 2 | 98 |
6. Primary Endpoint
The registry lists the primary outcome as Percentage of Participants With Major Adverse Events (MAEs), measured over 12 Months.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | percentage of participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the percentage of participants with major adverse events through 12 months. Its definition includes all causes of death through 1 month, target-limb major amputation through 12 months, and/or target lesion revascularization through 12 months. The endpoint is expressed as a percentage of participants, so it is intended to represent the proportion meeting the composite event definition rather than a count of event episodes alone.
A composite endpoint combines more than one type of outcome. In general, this can capture a broader range of clinically important events in one measure, but the components may differ in frequency, severity, and timing. A single composite result therefore does not necessarily describe the pattern for each component. The record does not provide component-specific results or a single comparison of the composite between the randomized groups.
The time windows are part of the endpoint definition and matter to its interpretation: death is counted through 1 month, while major amputation and target lesion revascularization are assessed through 12 months. The registry does not report further details about event ascertainment, adjudication for this primary endpoint, or how participants with incomplete follow-up were handled. The rationale for selecting this endpoint is not reported in the registry record. In general, a prespecified endpoint gives a trial a defined outcome for evaluating its main question; the available record identifies that outcome but does not provide the result needed to assess the comparison.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies the trial as randomized and names the primary endpoint, but the primary comparison is not reduced to one result. The stated endpoint is the percentage of participants with major adverse events, with component events assessed through different time windows. No event percentages, group-specific endpoint estimates, confidence interval, or p-value for a single primary comparison are included in the registry record for this analysis. The available information therefore does not support a conclusion about the direction or precision of the primary comparison.
That absence is important. A trial’s title and objective describe what investigators set out to evaluate; they do not establish what the outcome comparison showed. Likewise, the status “completed” and the registered enrollment do not substitute for outcome results. The registry record does not give a single estimate for the primary endpoint that can be interpreted as a difference between ELUVIA and Zilver PTX.
In general, an effect estimate describes the observed contrast between groups, while a confidence interval describes the range of values compatible with the data and the method used to calculate it. A narrow interval generally indicates greater precision than a wide interval. Neither an estimate nor its interval is reported for the primary comparison in the registry record. No assessment of statistical significance or precision is possible from this endpoint record alone.
The primary endpoint is composite. In general, a composite result can be influenced more strongly by components that occur more often, even if other components are more severe. Separate component results are needed to understand whether the overall pattern is consistent across death, major amputation, and target lesion revascularization. Component-specific primary endpoint results are not reported in the registry record. The different follow-up windows also mean the components do not share an identical observation period.
The record lists a long lesion substudy and a PK substudy, as well as a range of secondary outcomes. Their presence does not establish that their results are comparable to the primary randomized comparison or that they answer the same question. Their analysis populations, relationship to the main trial, and detailed results are not reported in the registry record. The subgroup structure and any handling of multiple comparisons are also not reported.
Thus, the record supports a description of the trial design and endpoint definition, but not a quantitative judgment about the primary treatment contrast. The appropriate statistical interpretation is limited by the missing comparison estimate, missing uncertainty measure, and lack of component-level results in the information. No conclusion about treatment benefit, lack of benefit, or equivalence follows from these omissions.
9. Statistical Methods Explained
What does randomization contribute?
Randomization assigns participants to treatment groups using a chance-based process. As a general statistical principle, this helps reduce systematic differences between groups at the start of a trial. It does not ensure identical groups, and it does not remove the need to report the analysis population, follow-up, outcome definitions, and statistical methods. The registry identifies this study as randomized, but the assignment procedure and allocation concealment are not reported in the registry record.
The trial is also listed as single-masked. Masking can reduce the influence of expectations or knowledge of treatment assignment on some parts of trial conduct or assessment. Which people were masked and how the masking was implemented are not reported in the registry record, so the practical meaning of “single” cannot be specified from these registry entries.
How should a percentage endpoint be understood?
The primary outcome is a percentage of participants meeting a composite definition. In general, a participant-level percentage is distinct from a total count of event episodes: a participant may meet an endpoint definition through one or more qualifying events, while the percentage concerns whether the participant meets the definition. The registry does not provide the event-counting and participant-classification details needed to explain precisely how multiple events were handled for the primary endpoint.
The endpoint combines death, target-limb major amputation, and target lesion revascularization. These are different outcomes and have different follow-up windows in the definition. General interpretation of a composite requires attention to which components contribute to it and whether component patterns align. The component-specific primary results are not reported in the registry record.
What would an effect estimate and interval say?
In general, an effect estimate expresses the observed contrast between treatment groups on a defined scale. A confidence interval conveys uncertainty around that estimate under the statistical method used. It is not a guarantee that the true effect lies within the interval, and it does not by itself address biases or whether the endpoint is clinically important. The registry entries do not include a primary comparison estimate or confidence interval, so neither the magnitude nor the precision of the primary contrast can be assessed.
A p-value, when reported, addresses how compatible the observed data are with a specified null hypothesis under a statistical model. It is not the probability that the null hypothesis is true, nor does it measure the size or importance of an effect. No p-value for a single primary comparison is reported in the registry record. The registry’s description does not provide the model, test, or adjustment method used for primary-outcome analysis.
Why do analysis populations matter?
Different analysis populations can answer different questions. In general, an analysis based on assigned treatment groups preserves the comparison created by randomization, while analyses based on treatment received or on completion of follow-up can involve different assumptions and potential sources of bias. The registry record does not report the primary analysis population or explain how participants who discontinued, crossed over, or lacked endpoint data were handled. Those details should not be inferred from the randomized design alone.
Outcome denominators are also necessary for interpreting percentages. A registered enrollment does not establish the denominator used at each outcome time point, especially when follow-up or outcome availability may vary. The registry entries do not give primary-endpoint denominators by group.
What is the role of the planning illustration?
The statistical assumptions recorded for planning illustrations are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. These are planning assumptions, not evidence that the original trial was designed using them. The record explicitly characterizes the illustration as computed from the observed effect and not as the trial’s own design. It should not be interpreted as observed power or as a finding about the primary comparison. The registry entries do not include a primary effect estimate from which to assess a planning calculation.
In general, sample-size planning explores how much information a future study might need under chosen assumptions about the effect, variability, allocation, and error rates. Results are conditional on those assumptions. They are not a substitute for the trial’s observed estimate and uncertainty, and they do not establish that a study was adequately or inadequately designed. No sample-size justification for the original trial is reported in the registry record.
What do the design labels not tell us?
The parallel design indicates that the record describes separate randomized treatment groups rather than a crossover structure. Beyond that label, the registry entries do not specify the detailed schedule of treatment, follow-up visits, or how missing observations were handled. General statistical explanations can clarify what design features mean, but they cannot fill in unreported protocol details. The registry record does not report interim analyses, a statistical analysis plan, or the rationale for selecting the primary endpoint.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 11 outcome measures and 2 analyses, including several secondary outcomes. These include clinical events, sustained clinical improvement, hemodynamic improvement, Walking Impairment Questionnaire scores, and 6-Minute Walk Test distance and speed. Multiple outcomes and analyses can create multiplicity: in general, the more statistical comparisons considered, the greater the chance that at least one result may appear notable by chance if no adjustment or prespecified interpretation strategy is used.
The registry entries do not report whether multiplicity adjustments were planned or applied, which outcomes were included in each analysis, or how the analyses were prioritized. The record also does not report a statistical analysis plan or interim analyses. These omissions prevent assessment of how the trial addressed the interpretation of multiple outcomes and comparisons.
The primary endpoint itself combines different event types and time windows, but the registry record does not give one comparison across its categories or time points. It does not provide component-specific results for the primary endpoint in the registry record. That limits both interpretation of the composite and the ability to compare its components.
Missing-data handling and analysis populations are not reported in the registry record. The registry entries do not describe the amount or pattern of missing outcome data, the denominators used for the primary endpoint, or methods for handling incomplete follow-up. Without those details, it is not possible to assess whether missingness could affect the comparison or what assumptions an analysis may have required.
In general, transparent reporting of analysis populations, missing-data methods, and multiplicity procedures helps readers judge how robustly results answer the trial’s main question. Those details are not available in the registry record. Their absence should not be interpreted as proof that a method was or was not used.
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 |
|---|---|---|---|
| ELUVIA Stent Implantation | 243 | 309 | 78.6% |
| Zilver PTX Stent Implantation | 126 | 156 | 80.8% |
| Long Lesion Substudy | 40 | 50 | 80.0% |
| PK Substudy | 13 | 13 | 100.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| ELUVIA Stent Implantation | 58 of 309 |
| Zilver PTX Stent Implantation | 28 of 156 |
| Long Lesion Substudy | 13 of 50 |
| PK Substudy | 6 of 13 |
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 |
|---|---|
| ELUVIA Stent Implantation | 186 of 309 |
| Zilver PTX Stent Implantation | 91 of 156 |
| Long Lesion Substudy | 27 of 50 |
| PK Substudy | 11 of 13 |
Most frequent serious adverse event terms
| Event term | Organ system | ELUVIA Stent Implantation | Zilver PTX Stent Implantation | Long Lesion Substudy | PK Substudy |
|---|---|---|---|---|---|
| Peripheral artery stenosis | Vascular disorders | 85 of 309 | 42 of 156 | 10 of 50 | 2 of 13 |
| Intermittent claudication | Vascular disorders | 36 of 309 | 13 of 156 | 9 of 50 | 2 of 13 |
| Peripheral arterial occlusive disease | Vascular disorders | 27 of 309 | 15 of 156 | 3 of 50 | 1 of 13 |
| Pneumonia | Infections and infestations | 16 of 309 | 15 of 156 | 8 of 50 | 1 of 13 |
| Femoral artery occlusion | Vascular disorders | 27 of 309 | 6 of 156 | 4 of 50 | 2 of 13 |
| Angina pectoris | Cardiac disorders | 14 of 309 | 8 of 156 | 2 of 50 | 2 of 13 |
| Atrial fibrillation | Cardiac disorders | 16 of 309 | 6 of 156 | 1 of 50 | 1 of 13 |
| Cardiac Failure | Cardiac disorders | 14 of 309 | 5 of 156 | 5 of 50 | 0 of 13 |
| Coronary artery disease | Cardiac disorders | 15 of 309 | 4 of 156 | 2 of 50 | 2 of 13 |
| Acute myocardial infarction | Cardiac disorders | 13 of 309 | 6 of 156 | 2 of 50 | 2 of 13 |
Most frequent non-serious adverse event terms
| Event term | Organ system | ELUVIA Stent Implantation | Zilver PTX Stent Implantation | Long Lesion Substudy | PK Substudy |
|---|---|---|---|---|---|
| Peripheral artery stenosis | Vascular disorders | 18 of 309 | 6 of 156 | 3 of 50 | 0 of 13 |
| Vascular procedure complication | Injury, poisoning and procedural complications | 16 of 309 | 9 of 156 | 2 of 50 | 0 of 13 |
| Intermittent claudication | Vascular disorders | 10 of 309 | 11 of 156 | 2 of 50 | 1 of 13 |
| Pain in extremity | Musculoskeletal and connective tissue disorders | 11 of 309 | 6 of 156 | 3 of 50 | 1 of 13 |
| Arthralgia | Musculoskeletal and connective tissue disorders | 12 of 309 | 2 of 156 | 1 of 50 | 0 of 13 |
| Oedema peripheral | General disorders | 12 of 309 | 0 of 156 | 1 of 50 | 1 of 13 |
| Dyspnoea | Respiratory, thoracic and mediastinal disorders | 7 of 309 | 4 of 156 | 1 of 50 | 0 of 13 |
| Peripheral arterial occlusive disease | Vascular disorders | 6 of 309 | 3 of 156 | 2 of 50 | 0 of 13 |
| Angina pectoris | Cardiac disorders | 8 of 309 | 2 of 156 | 1 of 50 | 0 of 13 |
| Back pain | Musculoskeletal and connective tissue disorders | 4 of 309 | 5 of 156 | 0 of 50 | 0 of 13 |
Serious events with the highest arm-level rate: peripheral artery stenosis (27.5%), sepsis (23.1%), intermittent claudication (18.0%), pneumonia (16.0%), femoral artery occlusion (15.4%).
The registry lists serious adverse event figures for four labeled groups: ELUVIA Stent Implantation, Zilver PTX Stent Implantation, Long Lesion Substudy, and PK Substudy. For the ELUVIA group, the record gives 309 at risk and 243 affected for serious events, and 309 at risk and 186 affected for other events. For Zilver PTX, it gives 156 at risk and 126 affected for serious events, and 156 at risk and 91 affected for other events. The long lesion substudy figures are 50 at risk and 40 affected for serious events, and 50 at risk and 27 affected for other events. The PK substudy figures are 13 at risk and 13 affected for serious events, and 13 at risk and 11 affected for other events.
The registry also lists death counts of 58, 28, 13, and 6 for those respective groups. The definition and time window for these counts are not reported in the registry record. The group labels include substudies, and the record does not explain whether these populations overlap; their counts should not be added or treated as mutually exclusive.
The most frequent listed serious-event terms include Peripheral artery stenosis at 27.5%, Sepsis at 23.1%, Intermittent claudication at 18.0%, Pneumonia at 16.0%, Femoral artery occlusion at 15.4%, and Angina pectoris at 15.4%. The denominator and precise interpretation of these term percentages are not reported in the registry record. These figures describe recorded safety categories, but they are not a direct randomized comparison of the primary endpoint and do not by themselves establish a causal difference between treatments.
12. What the Result Does, and Does Not, Mean
The record establishes that a randomized, single-masked, parallel trial compared ELUVIA and Zilver PTX stent implantation for superficial femoral and/or proximal popliteal artery lesions. It identifies major adverse events through 12 months as the primary outcome and defines the events and their follow-up windows. It also records an enrollment of 524, a completed status, and several secondary outcomes and substudies.
Those details describe the trial question and design; they do not provide a single primary-endpoint result. The record does not give the group-specific primary outcome percentages, a comparison estimate, a confidence interval, or a p-value for one primary comparison in the registry record for this analysis. Accordingly, the record does not establish the direction, size, or precision of a primary treatment contrast.
In general, a nonsignificant test, if one were available, would not by itself establish that treatments are equivalent. Equivalence or noninferiority claims require a suitable prespecified framework and corresponding analysis. No such framework or analysis is reported in the registry record. Nor does absence of a single comparison mean that no analysis was conducted; it means the available information does not present one in a form that supports interpretation.
The composite endpoint also cannot be read as a result for each component. General interpretation of a composite requires component-specific information, particularly when event types and follow-up windows differ. Component-specific primary results are not reported in the registry record. The safety figures are separate registry listings and do not replace a randomized analysis of the primary endpoint.
Thus, the statistical meaning is chiefly definitional and methodological: the record identifies a randomized comparison and a clinically framed composite outcome, but the primary comparison is not available as a single interpretable estimate. No conclusion about benefit, lack of benefit, equivalence, or treatment choice follows from the information.
13. Why This Trial Matters Statistically
This trial raises a clear statistical question: how to compare a participant-level composite safety endpoint between randomized stent groups when its components differ in type and follow-up window. The endpoint includes all-cause death through 1 month and target-limb major amputation and target lesion revascularization through 12 months. A reader needs the overall comparison and component results to understand both the composite pattern and its precision.
The randomized, parallel design is relevant because random assignment is intended, in general, to support a fair comparison of treatment groups. Yet design labels alone are not enough to evaluate a result. Outcome denominators, the analysis population, missing-data handling, endpoint estimates, and uncertainty measures are also important. Those details are not reported in the registry record.
The record also describes a long lesion substudy and a PK substudy, alongside multiple secondary outcomes. This makes clear why interpretation should distinguish the primary randomized question from subgroup or additional outcome analyses. In general, multiple comparisons and overlapping study populations can complicate interpretation; the registry does not report how those issues were handled or whether the substudy populations overlap.
Finally, the planning assumptions illustrate why sample-size calculations must be kept separate from observed evidence. The stated planning illustration is based on a fraction of an observed effect and is not the trial’s own design. It cannot substitute for a reported treatment estimate or be treated as observed power. The statistical importance of the record is therefore in defining the comparison and exposing what result-level information is needed for a complete interpretation.
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 principal limitation for interpreting the primary question is that the registry record does not present a single comparison for the primary endpoint. Group-specific percentages, denominators, an effect estimate, an uncertainty interval, and a p-value for that comparison are not reported in the registry record. Without them, the primary treatment contrast cannot be described quantitatively.
The endpoint is a composite, but component-specific primary results are not reported in the registry record. Its definition uses different time windows for death, major amputation, and target lesion revascularization. The registry entries do not provide additional details about event ascertainment, handling of repeated events, or follow-up completeness. These gaps limit assessment of how the composite was constructed and what may have driven it.
Key statistical and operational details are not reported in the registry record, including the primary analysis population, missing-data methods, randomization procedure, allocation concealment, masking roles, and whether interim analyses occurred. A statistical analysis plan and multiplicity procedures are also not reported. Their absence from the available information prevents assessment of the prespecified analysis approach; it does not establish whether a particular procedure was or was not used.
The safety record includes the main randomized group labels and two substudy labels. Whether those populations overlap is not reported in the registry record, so their counts should not be combined. The meaning and time window of the listed death counts and the denominators for serious-event term percentages are also not reported. These safety listings should therefore be read as descriptive registry entries rather than as a complete comparative safety analysis.
Finally, the registry does not report further eligibility details or the rationale for the endpoint and original sample-size design. General statistical principles can explain why such details matter, but they cannot resolve these trial-specific uncertainties.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: ELUVIA™ Drug-eluting Stent Versus Zilver® PTX® Stent — NCT02574481.
- Registry record last updated 2023-05-08; status last verified 2023-04.
- Results first posted 2019-01-07.
- 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.
Continue through the Clinical Biostats statistical pathway
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 registry record describes NCT02574481, a randomized, single-masked, parallel trial comparing ELUVIA with Zilver PTX stent implantation for superficial femoral and/or proximal popliteal artery lesions. It lists an enrollment of 524 and a completed status. The primary endpoint is the percentage of participants with major adverse events, defined using death through 1 month and target-limb major amputation and/or target lesion revascularization through 12 months.
The record also lists secondary outcomes, a long lesion substudy, a PK substudy, and serious adverse event figures. However, the registry entries summarized for this analysis do not provide a single primary-endpoint comparison, group-specific primary outcome estimates, or uncertainty measures. Analysis-population details, missing-data methods, and multiplicity procedures are not reported in the registry record. The available information therefore supports a description of the design and outcome definitions, but not a quantitative interpretation of the primary treatment contrast.