Bard® LifeStent® Vascular Stent Delivery System Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Bard® LifeStent® Vascular Stent Delivery System Study (NCT01179984), a na na study. The primary outcome is Acute Effectiveness: Percentage of Stents With Successful Delivery.

2. Clinical Question

Thus, the record identifies a device-delivery question rather than a comparative question about outcomes under alternative treatments. It does not state how many stents were assessed for the primary endpoint, how the percentage was calculated for the mean, or how many observations contributed to that summary. These details are not reported in the registry record. The trial is marked completed, but completion status alone does not supply the missing endpoint result.

3. Trial Design

This completed study is registered as a single-group device study of the Bard® LifeStent® Vascular Stent System. The sponsor is C. R. Bard. The registry lists the condition as Peripheral Vascular Disease, enrollment as 76, and the phase as NA. The recorded start is 2010-06 and the primary completion is 2010-10. The study status is COMPLETED.

The listed arm is PTA and study stent, and its description names the Bard® LifeStent® Vascular Stent System. Allocation is marked NA, masking is NONE, and the model is SINGLE GROUP. The record therefore does not describe random assignment or a masked comparison. It does not identify a separate control arm. As a result, the registry entry does not support a direct between-group estimate of treatment effect.

The purpose stated in the record is to evaluate effectiveness and safety of a new delivery system for the Bard® LifeStent® Vascular Stent System. The primary endpoint is acute delivery effectiveness at implantation (Day 0). Primary Target Lesion Patency is listed among the secondary outcomes. The record states that there are three outcome measures overall, but the details of the remaining measures are not reported in the registry record. It lists zero analyses; this means analysis results are not entered in the record, not that no analyses were performed.

There is no description of the planned enrollment rationale, eligibility rules, enrollment flow, or protocol deviations. The registry record also does not report an analysis population or how the single-group observations were handled in statistical analysis. Such omissions limit what can be inferred about conduct and analysis, independently of the trial's completed status.

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

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.

Population: The baseline analysis population is comprised of subjects who present with lifestyle-limiting claudication or ischemic rest pain that are candidates for PTA and stenting.

6. Primary Endpoint

The registry lists the primary outcome as Acute Effectiveness: Percentage of Stents With Successful Delivery, measured over At implantation (Day 0).

The primary endpoint is titled Acute Effectiveness: Percentage of Stents With Successful Delivery. It is measured at implantation (Day 0). The definition requires successful delivery and a post-deployment stent length within 10% of the pre-deployment length. The registry specifies the percentage of stents as the unit and identifies the parameter as a mean, with a 95% confidence interval for dispersion.

This endpoint is used to describe immediate technical delivery performance under the study definition. Its focus is the delivery procedure and the relation between intended and post-deployment stent length, rather than a later clinical outcome. It is therefore distinct from the listed secondary outcome, Primary Target Lesion Patency. The record does not define the time frame or measurement method for that secondary outcome.

The endpoint definition makes clear what a successful delivery is intended to mean, but it does not give the observed percentage, mean, confidence interval bounds, or denominator used in the analysis. The number of stents actually contributing to the endpoint is not reported in the registry record. Without those results, the endpoint can be described but its observed performance and statistical precision cannot be assessed.

In general, a confidence interval expresses uncertainty around an estimate under the statistical method used to construct it. Its width is informative about precision, but interpretation also depends on the analysis and the amount and pattern of available data. Here, the registry names a 95% confidence interval without posting its limits or describing how it was calculated. The endpoint's summary therefore cannot be independently evaluated from the registry entry.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary endpoint as a mean of a continuous measure, with a 95% confidence interval. The measure is expressed as a percentage of stents and is defined by a binary success condition at implantation. The record does not explain the statistical steps used to convert those observations into the stated mean, nor does it identify the endpoint denominator. Those details are not reported in the registry record.

What does a mean describe?

In general, a mean describes the arithmetic average of observations on a numerical scale. It can provide a compact summary, but its interpretation depends on what each observation represents and how the observations were collected. For this endpoint, the record names a percentage of stents and a mean. It does not specify whether the percentage was calculated across all observed stents or whether a percentage was first calculated within each participant and then averaged. Those approaches can answer different questions when participants contribute different numbers of stents. The registry does not resolve that issue.

Because the definition classifies delivery as successful only when its stated conditions are met, the underlying observations concern whether delivery meets that criterion. The registry does not report the underlying counts or a distribution of observations. It is therefore not possible to assess the mean's calculation, the influence of any unusual observations, or whether the statistical summary matches the intended unit of analysis.

What does a confidence interval communicate?

In general, a confidence interval gives a range of estimates compatible with the observed data and the method's assumptions. A narrower interval indicates greater precision under those assumptions; a wider interval indicates more uncertainty. A 95% confidence interval does not mean that the underlying value has a 95% probability of lying in the particular interval after it has been calculated. Rather, the confidence level describes the long-run behavior of the interval procedure under its assumptions.

The registry names a 95% confidence interval but does not report its lower or upper limit. It also does not state the method used to construct it, whether the interval accounts for clustering or repeated observations, or how missing endpoint observations were handled. Thus, neither the size nor the appropriateness of the interval can be assessed from the entry. General principles about confidence intervals cannot fill in an unreported estimate or method.

Why does the single-group design matter?

In general, a comparative treatment effect requires a contrast between outcomes under different conditions, often through a suitable control group. A single-group study can describe what was observed among participants receiving the study intervention, but it does not supply a concurrent randomized comparison. Differences between a single-group observation and an external expectation may reflect other factors as well as the intervention. This registry record does not identify an external benchmark or a comparative analysis.

The allocation field is NA, masking is NONE, and the model is SINGLE GROUP. These entries make it important to avoid interpreting the arm label as a control comparison. The record does not describe randomization, masking, or a separate comparator. It also does not report adjusted analyses that might address measured differences in a comparative setting.

What can the analysis entries tell a reader?

The record lists zero analyses. That is a statement about analyses entered in the registry record; it does not show whether analyses were conducted outside the registry. No primary endpoint estimate, confidence interval, test result, or model specification is posted. The statistical plan, including any prespecified model or handling of repeated measurements, is not reported in the registry record.

The record's sample-size assumptions describe a planning illustration computed from the observed effect, rather than the trial's own design. The stated assumptions are a two-sided significance level 0.05, equal allocation between the two arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. For time-to-event tables, the stated convention is a total number of events using Schoenfeld; other tables use participants per arm. These are planning assumptions, not observed power and not evidence that the single-group study used a two-arm design. The observed endpoint effect needed to interpret such an illustration is not reported in the registry record. No sample-size justification for the trial is reported.

In general, planning calculations describe the sample size associated with specified assumptions and a target analysis. They do not measure the probability that a completed study has detected a true effect, and a planning illustration based on an observed effect is not a substitute for a prespecified design rationale. The record does not state that these assumptions were the basis for enrollment or that the illustration reflects the actual study design.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists three outcome measures overall, identifies acute delivery effectiveness as the primary endpoint, and lists Primary Target Lesion Patency among secondary outcomes. It does not identify the remaining outcome measures or give detailed results for the secondary outcome. No multiplicity strategy is reported in the registry record. It is therefore unknown whether the study planned to adjust for multiple endpoints, define a testing hierarchy, or treat secondary outcomes as descriptive.

Multiplicity matters in general because examining multiple outcomes or analyses can increase the chance of a seemingly notable result arising by chance. The appropriate interpretation depends on what was prespecified and how results were analyzed. Since the registry lists zero analyses and no hypothesis-test results, there is no posted testing family or adjustment to evaluate. It would be inappropriate to infer either that multiplicity was controlled or that it was ignored.

Missing-data procedures are not reported in the registry record. The entry does not say whether all enrolled participants contributed to each outcome, how unavailable measurements were handled, or whether any imputation or sensitivity analysis was used. It also does not state the analysis population, such as whether an intention-to-treat or evaluable-population approach was planned. The endpoint denominator is not reported, so the amount of missing primary endpoint information cannot be assessed.

These omissions affect interpretation because endpoint estimates can depend on which observations are included and on assumptions about missing observations. In general, a complete-case analysis and an analysis using imputation may answer different questions and rely on different assumptions. No particular method can be attributed to this study from the registry entry. The reported enrollment is not, by itself, evidence that every enrolled participant contributed data to every endpoint.

11. 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 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: other (28.9%), in-stent arterial restenosis (21.1%), peripheral arterial occlusive disease (9.2%), femoral arterial stenosis (7.9%), femoral arterial occlusion (6.6%).

For the PTA and Study Stent group, the registry records 76 at risk for serious adverse events and 49 affected. It records 76 at risk for other adverse events and 70 affected, and lists 8 deaths. These entries describe the counts recorded in the registry; the record does not provide further detail about timing, severity grading, attribution, or the relationship between these categories.

The listed serious adverse event terms include Other (28.9%), In-stent Arterial Restenosis (21.1%), Peripheral arterial occlusive disease (9.2%), Femoral arterial stenosis (7.9%), Femoral Arterial Occlusion (6.6%), and Iliac Artery Stenosis (5.3%). The entry does not explain whether people could contribute more than one event or appear under more than one term. The percentages should therefore be read as the listed term values, not added together or interpreted as mutually exclusive participant proportions.

These safety figures are descriptive and do not establish causation. The registry does not report a comparator group, event timing, or an analysis of relative risk. The counts also do not reveal the clinical circumstances of the events. More detailed safety interpretation is not possible from the registry record alone.

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

The record is useful for identifying the study's stated purpose, design, primary endpoint definition, and some adverse-event information. It documents a completed, single-group study of the Bard® LifeStent® Vascular Stent System, with acute delivery effectiveness defined at implantation. It also identifies Primary Target Lesion Patency as a secondary outcome and gives the listed adverse-event counts for the study group.

The most important limit is that the primary endpoint result is not reported in the registry record. Without its estimate and confidence interval, the record does not show the observed level of delivery success or the precision of that estimate. The enrollment figure cannot be treated as the endpoint denominator, because the record does not say how many stents or participants contributed to the primary analysis.

The design also limits what a result could mean. A single-group study without a separate comparator can describe the observed experience in that group, but it cannot by itself establish a difference relative to another device, procedure, or treatment. The record does not report a randomized comparison or a control group. Accordingly, no comparative treatment effect can be inferred from this entry.

The posted safety counts provide a descriptive account, not a causal assessment. The registry does not report event timing, attribution, or a comparison that would help distinguish events associated with the study intervention from events arising for other reasons. Nor does it provide enough detail to resolve overlap among adverse-event categories.

These points do not demonstrate that the intervention did or did not achieve the endpoint, nor do they establish that analyses or additional data do not exist elsewhere. They describe the limits of the registry record. The appropriate reading is that the record specifies what was intended to be measured and reports selected safety entries, while leaving the primary numerical result and key analysis details unreported.

13. Why This Trial Matters Statistically

This trial illustrates why a clearly named endpoint and a posted endpoint result are different pieces of evidence. The registry defines acute delivery success in operational terms: delivery must be successful, and the post-deployment stent length must be within 10% of its pre-deployment length. That definition makes the intended measure understandable. But without the estimate, denominator, and confidence interval, readers cannot judge the observed frequency or its precision.

It also illustrates the importance of matching the interpretation to the design. The record identifies a single-group study, not a randomized comparison. An arm label that mentions PTA and a study stent does not establish a separate control group. Statistical descriptions should therefore remain within the scope of the observed group rather than implying a comparative effect.

The entry distinguishes immediate delivery performance from a secondary outcome of Primary Target Lesion Patency. This separation matters because an acute technical endpoint and a later clinical or vessel outcome address different questions. The registry does not give the secondary outcome's detailed results or timeframe, so readers cannot use it to extend conclusions about the acute endpoint.

Finally, the record shows how registry completeness affects statistical interpretation. Enrollment and adverse-event entries are available, but analysis results, endpoint precision, missing-data methods, and multiplicity procedures are not. Reporting those elements would help readers understand which observations contributed, how uncertainty was quantified, and what scope of inference was intended. In their absence, careful statistical interpretation requires describing the design and recorded counts without filling gaps with assumptions.

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 primary endpoint is defined but its numerical result is absent. The registry does not report the mean, confidence interval limits, endpoint denominator, or the number of stents contributing to the analysis. This prevents assessment of the observed acute delivery performance and its precision.

The single-group design and lack of a described comparator limit comparative interpretation. Allocation is listed as NA and masking as NONE. The record does not describe a control group, randomization, or a blinded outcome assessment. It therefore offers no registered basis for estimating a comparative treatment effect.

Important study and analysis details are also unreported. Eligibility criteria, participant characteristics, the method for deriving the percentage and mean, missing-data handling, analysis populations, protocol deviations, and the statistical plan are not reported in the registry record. The record lists zero analyses and does not give detailed results for Primary Target Lesion Patency or the other outcome measures.

Safety interpretation is limited by absent information about event timing, attribution, and overlap between categories. The listed counts and terms are descriptive, and the record does not provide a comparator or event-level context. The enrollment figure cannot resolve these limitations or serve as a denominator for every outcome.

These are limitations of the registry entry as an evidence source. They do not establish that the study lacked a protocol, collected no further data, or performed no analyses. They mean that those details cannot be evaluated from the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Bard® LifeStent® Vascular Stent Delivery System Study — NCT01179984.
• Registry record last updated 2018-11-08; status last verified 2018-10.
• Results first posted 2017-03-09.
• 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 registry record describes NCT01179984, the Bard® LifeStent® Vascular Stent Delivery System Study, sponsored by C. R. Bard. It is marked COMPLETED, with start 2010-06, primary completion 2010-10, and enrollment 76. The condition is Peripheral Vascular Disease. The study is listed as SINGLE GROUP, with allocation NA and masking NONE.

The primary endpoint is acute effectiveness, defined as successful delivery with post-deployment stent length within 10% of pre-deployment length, measured at implantation (Day 0). The registry specifies a mean and 95% confidence interval but does not report the result or interval limits. Primary Target Lesion Patency is listed as a secondary outcome. The entry lists adverse-event counts and terms but does not report analysis results; it records zero analyses.