TAXUS PERSEUS Small Vessel: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for TAXUS PERSEUS Small Vessel (NCT00489541), a non-randomized phase 3 study. The primary outcome is In-stent Late Loss Measured by Quantitative Coronary Angiography (QCA).

2. Clinical Question

The clinical question concerns an angiographic measure after stent placement, rather than a direct randomized comparison of clinical outcomes between devices. In-stent late loss is defined as the post-procedure minimum lumen diameter minus the follow-up minimum lumen diameter measured within the stent. The record also lists target lesion failure at 12 months as a secondary outcome. That composite includes ischemia-driven revascularization of the target lesion, myocardial infarction, or death related to the target vessel.

The small-vessel setting is specified by the vessel diameter range, and the lesions are described as de novo and atherosclerotic. These eligibility details define the clinical setting to which the trial question applies; they do not establish that every participant had the same lesion characteristics or risk. Further eligibility details and participant characteristics are not reported in the registry record.

Because allocation was non-randomized and the trial model is single-group, the primary question is principally descriptive: what angiographic result was observed among the defined patients who received the study device and completed angiographic follow-up? The record does not provide the numerical result needed to answer that question. It therefore cannot support a conclusion about the size or precision of the observed late loss from the information recorded.

3. Trial Design

TAXUS PERSEUS Small Vessel is recorded as a Phase 3, completed, prospective, non-randomized, single-group trial with no masking. The sponsor was Boston Scientific Corporation. The registry lists an enrollment of 224 and describes percutaneous coronary intervention with implantation of the TAXUS Element paclitaxel-eluting coronary stent system as the intervention.

The device was evaluated in people with de novo atherosclerotic lesions in native coronary arteries, described as up to 20 mm in length and in vessels at least 2.25 mm and less than 2.75 mm in diameter. The primary endpoint was measured at 9 months after the index procedure. The registry gives a study start of 2007-07 and primary completion of 2009-06.

Non-randomized allocation means participants were not assigned at random to competing treatments under the design described in the record. The record classifies the trial as single-group, so it does not describe a concurrent randomized control arm for evaluating the primary endpoint. Although historical bare metal stent safety figures appear in the adverse-event information, the record explicitly warns that the arms are not a like-for-like control comparison.

The primary analysis population is described as the intent-to-treat population, defined in the record as patients who had a study device implanted at the target lesion and completed angiographic follow-up. This operational definition includes a follow-up completion condition, so it should not be treated as a conventional all-enrolled analysis without qualification. The number meeting this definition is not reported in the registry record.

The record lists two outcome measures and two analyses, but it does not provide the primary endpoint estimate, its standard deviation, a confidence interval, or a test result. Additional details of the protocol, recruitment, follow-up completion, and analysis procedures are not reported in the registry record. Consequently, the design can be described, but its implementation and the precision of the primary finding cannot be fully assessed from the 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.

12-Month Clinical Follow-up

Reasons for not completing this period:

9-Month Angiographic Follow-up

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The primary analysis population for the superiority testing of the primary endpoint, 9-month in-stent late loss, is the intent-to-treat (ITT) population, i.e. all patients who had a study device implanted at the target lesion and completed their angiographic follow-up.

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 In-stent Late Loss Measured by Quantitative Coronary Angiography (QCA), measured over 9 months post-index procedure.

The primary endpoint is in-stent late loss measured by quantitative coronary angiography, in millimeters, at 9 months after the index procedure. It is defined as the post-procedure minimum lumen diameter minus the follow-up minimum lumen diameter, with the minimum lumen diameter measured within the stent at each time point. The registry specifies a mean as the endpoint summary and standard deviation as its dispersion measure.

This endpoint turns a pair of angiographic measurements into a continuous measure of change in lumen diameter within the stent. In general, continuous outcomes retain information about the magnitude of a measurement rather than reducing it to categories such as event or no event. A mean describes the central value across the analyzed observations, while a standard deviation describes how dispersed individual measurements are around that mean. Neither alone gives the full shape of the data distribution.

In general, an angiographic measure can be useful for characterizing a device-related anatomical outcome at a defined follow-up time. It is distinct from a clinical event endpoint: a measured change in lumen diameter does not itself establish whether a patient experienced target lesion failure, myocardial infarction, or death. The registry separately lists target lesion failure at 12 months as a secondary outcome, with its components defined in the record.

The numerical primary endpoint result and its standard deviation are not reported in the registry record. Therefore, the endpoint definition is available, but the observed mean, variability, and precision cannot be evaluated from the recorded information.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical information recorded for this trial is enough to identify the primary measure and its intended summary, but not enough to reproduce or fully assess the analysis. The endpoint is continuous, summarized by a mean with a standard deviation, and measured at 9 months. The record does not report the actual mean, standard deviation, confidence interval, test statistic, or p-value.

What does a mean and standard deviation describe?

In general, a mean represents the arithmetic center of a set of measurements. It is useful for describing an average value, but it can be influenced by unusually high or low observations. A standard deviation describes how spread out measurements are around the mean. A small standard deviation indicates that observations tend to cluster more closely around the average; a larger one indicates more variability. These summaries do not reveal whether the distribution is symmetric, whether there are outliers, or whether there are subgroups with different patterns.

For this study, each measurement concerns the difference between post-procedure and follow-up minimum lumen diameter within the stent. The endpoint description gives the direction of subtraction and measurement location. It does not give the observed distribution or describe data-quality checks, so no claims about the shape or quality of the endpoint data can be made.

What would a confidence interval add?

In general, a confidence interval expresses uncertainty around an estimated quantity. It gives a range of values compatible with the data and the method used, rather than presenting the point estimate as if it were exact. A narrower interval indicates greater precision under the assumptions of the method; a wider interval indicates less precision. A confidence interval does not by itself resolve bias due to non-randomized allocation or incomplete follow-up. No confidence interval for the primary endpoint is reported in the registry record.

What is the role of a hypothesis test?

In general, a hypothesis test evaluates how compatible observed data are with a specified null hypothesis under a statistical model. A p-value is not the probability that the null hypothesis is true, nor does it measure the clinical importance of an effect. Interpreting a test requires knowing the hypothesis, the analysis method, and the assumptions. The registry record does not report the primary endpoint test result or the full statistical plan, so the testing procedure cannot be reconstructed from the recorded information.

The sample-size assumptions recorded for planning illustrations specify a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The illustration is described as based on the observed effect, with the effect to detect expressed as a fraction of that observed effect. These assumptions describe planning illustrations, not observed power and not necessarily the trial's design. The trial itself is recorded as non-randomized and single-group. The protocol's own sample-size justification is not reported in the registry record.

Why does the design matter for statistical interpretation?

In general, random allocation helps make treatment groups comparable on average with respect to both measured and unmeasured factors. In a non-randomized study, treatment selection and participant characteristics may be associated. A single-group design also lacks a concurrent treatment contrast for estimating a comparative effect. Statistical adjustment can sometimes address measured differences, but it cannot automatically remove unmeasured confounding. The registry record does not describe an adjusted comparative analysis for the primary endpoint.

The historical bare metal stent information is not equivalent to a randomized control group. Differences across eras or cohorts can arise from changing care, selection criteria, measurement procedures, or follow-up. Because the record warns that the arms are not like-for-like, a numerical comparison of those summaries should not be read as a causal treatment effect.

Why can over-dispersion matter?

In general, over-dispersion occurs when observed variability is greater than a model assumes. If a model underestimates variability, standard errors can be too small and intervals too narrow, making results appear more precise than they are. This issue is particularly relevant to count outcomes when a model assumes a particular mean-variance relationship. The primary endpoint is continuous and is summarized by a mean and standard deviation; the registry does not report a count model or an over-dispersion assessment. Whether any distributional or variance assumptions were checked is not reported in the registry record.

The planning illustration uses a normal approximation. In general, such an approximation relies on conditions that make the modeled sampling distribution adequately represented by a normal distribution. The registry record does not state how those conditions were evaluated or whether the approximation was used in the trial's own analysis. The planning description should therefore be distinguished from the analysis actually performed.

The registry entries support a clear description of the endpoint and broad design, but not a detailed audit of the statistical analysis. The trial's prespecified hypotheses, any covariate adjustments, handling of deviations, multiplicity strategy, interim analyses, and sensitivity analyses are not reported in the registry record. No statistical conclusion should be inferred from the endpoint definition or planning assumptions in the absence of the reported estimate and its uncertainty.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("TAXUS Element", "Historical Control Bare Metal Stent (BMS)")
n   <- c(197, 108)
m   <- c(0.38, 0.8)
sp  <- c(0.51, 0.53)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  TAXUS Element  197  0.380  0.510  0.308  0.452
CARM  Historical Control Bare Metal Stent (BMS)  108  0.800  0.530  0.699  0.901

11. Multiplicity, Missing Data and Analysis Populations

The registry lists two outcome measures and two analyses. The primary outcome is in-stent late loss at 9 months. The secondary outcome is the number of participants with target lesion failure at 12 months, defined as ischemia-driven revascularization of the target lesion, myocardial infarction, or death related to the target vessel. The numerical results for these outcomes are not reported in the registry record.

Multiplicity arises in general when a study tests or estimates several outcomes, time points, subgroups, or hypotheses. Considering many results can increase the chance of finding an apparently notable result by chance. A prespecified hierarchy or adjustment can help define how multiple tests should be interpreted. The registry record does not report a multiplicity strategy, so it is not possible to determine whether the primary and secondary outcomes were tested under a formal hierarchy or whether any adjustment was planned.

Missing data are important because the primary analysis population is defined as patients who had the study device implanted at the target lesion and completed angiographic follow-up. That differs from a definition based solely on enrollment. The number who completed follow-up, the number without an endpoint measurement, and the reasons for missing measurements are not reported in the registry record. The method used to handle missing data is also not reported.

The record labels the primary analysis population as intent-to-treat, while its accompanying definition requires angiographic follow-up completion. Because that definition is narrower than all enrolled participants, readers should use the stated operational definition rather than assume a conventional all-enrolled analysis. The record does not report sensitivity analyses evaluating how missing follow-up might affect the result.

Interim analyses, stopping rules, and the detailed statistical analysis plan are not reported in the registry record. Their absence from the record does not establish whether they occurred; it means their role in interpreting the findings cannot be assessed.

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 (26.4%), coronary artery stenosis (12.8%), coronary artery disease (3.6%), angina unstable (3.2%), non-cardiac chest pain (3.1%).

The registry's serious adverse event summary lists 100 affected among 224 at risk for the TAXUS Element group. For the historical bare metal stent group, it lists 70 affected among 125 at risk. The record also lists other adverse event figures: 75 affected among 224 at risk for TAXUS Element and 41 among 125 at risk for the historical group. These are descriptive registry summaries, not randomized comparisons.

The serious adverse event terms with the highest reported percentages are angina pectoris, 26.4%; coronary artery stenosis, 12.8%; coronary artery disease, 3.6%; unstable angina, 3.2%; non-cardiac chest pain, 3.1%; and myocardial infarction, 2.4%. The record does not explain whether participants could contribute to more than one term, or how the listed terms relate to the affected-participant totals. The percentages should not be added together or treated as mutually exclusive categories.

The historical group is not identified as a like-for-like control, and the trial is non-randomized and single-group. Therefore, these summaries do not establish that differences between groups were caused by the stent. The death counts are not reported in the registry record. Further details on event timing, severity grading, adjudication, and follow-up are not reported in the registry record.

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

The registry record establishes that TAXUS PERSEUS Small Vessel was designed to evaluate a paclitaxel-eluting stent in a specified small-vessel setting, with in-stent late loss measured by quantitative coronary angiography at 9 months as the primary endpoint. It also identifies target lesion failure at 12 months as a secondary outcome and records selected adverse-event summaries.

It does not report the numerical primary endpoint result. Without the mean late loss, its standard deviation, and an interval or test result, the observed magnitude and precision cannot be assessed. The record also does not report the secondary target lesion failure result. The endpoint definitions alone do not show what outcomes occurred.

The design is non-randomized and single-group. In general, results from such a design can describe outcomes in the treated group, but they do not provide the same basis for causal comparison as randomized allocation. Historical bare metal stent safety summaries are especially unsuitable as a direct treatment contrast because the registry warns that the groups are not like-for-like.

The endpoint is an angiographic measure, not a direct measure of every aspect of patient health. In general, an anatomical measurement and a clinical event outcome answer different questions. The record's secondary composite includes revascularization, myocardial infarction, or target-vessel-related death, but no result for that composite is recorded.

The recorded safety counts and event-term percentages offer descriptive information, but their interpretation is limited by the absence of details about event ascertainment, overlap between terms, timing, and comparative design. The death counts are not reported in the registry record. The available information therefore supports understanding the trial's question and some reported safety summaries, but not a claim that the device was superior, equivalent, or safer than an alternative.

In short, the registry record describes what was to be measured and how the trial was broadly structured. It does not include the primary result needed to judge the endpoint itself, and its design does not support a direct randomized comparison with the historical safety group.

14. Why This Trial Matters Statistically

This trial illustrates why design and endpoint definitions matter as much as a headline result. The primary outcome is a continuous angiographic measure, in-stent late loss, defined through minimum lumen diameter measurements at specified time points. Its mean and standard deviation would describe average change and variability, while a confidence interval would help communicate precision. The registry record provides the endpoint definition but not those numerical results.

The non-randomized, single-group classification also places clear boundaries on comparative interpretation. A single-group study can characterize observations after device implantation, but it cannot by itself separate the device's contribution from other influences on outcomes. Historical safety data may provide context, but the record explicitly cautions against treating the historical group as a like-for-like control.

The primary analysis population definition is another important statistical detail. It describes patients with an implanted device who completed angiographic follow-up. Because follow-up completion is required, the number included and the handling of participants without measurements matter for assessing selection and missing-data concerns. Those details are not reported in the registry record.

The case also shows why a clinical endpoint and an angiographic endpoint should not be conflated. The primary measure concerns lumen diameter within the stent at 9 months, whereas the secondary target lesion failure outcome is a composite of clinical events at 12 months. They represent different outcomes and time points, and the record does not report either numerical result.

For statistical readers, the key lesson is to separate a clearly described study question from evidence that is actually available to evaluate it. Design, endpoint definition, population, missingness, uncertainty, and comparator suitability all affect what can be inferred. Here, several design features are documented, but the missing outcome estimates prevent assessment of the primary result's size and precision.

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 registry record does not report the numerical primary endpoint result, its standard deviation, confidence interval, or test result. It also does not report the numerical result for target lesion failure at 12 months. This prevents assessment of the observed endpoint values and their precision.

The study is classified as non-randomized and single-group, with no masking. Accordingly, it does not provide a randomized concurrent comparison for the primary endpoint. Although historical bare metal stent safety figures are recorded, the registry explicitly states that the arms are not a like-for-like comparison. Differences in those summaries should not be treated as causal effects.

The stated primary analysis population requires both implantation at the target lesion and completion of angiographic follow-up. The number meeting this definition, the number with missing angiographic measurements, and reasons for missingness are not reported in the registry record. The record does not describe how missing data were handled or whether sensitivity analyses were performed.

The safety summaries are limited by missing detail. The registry record does not report death counts, event timing, adjudication procedures, or whether the listed serious-event terms could overlap within participants. The percentages for event terms cannot be assumed to represent disjoint categories.

The record does not report the detailed statistical analysis plan, multiplicity procedures, interim analyses, stopping rules, or the protocol's sample-size justification. Planning illustrations are described as based on the observed effect and specified assumptions, but they should not be mistaken for the trial's observed power or proof of a prespecified design rationale. Further participant, lesion, follow-up, and analysis details are not reported in the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: TAXUS PERSEUS Small Vessel — NCT00489541.
• Registry record last updated 2014-05-08; status last verified 2014-04.
• Results first posted 2011-06-28.
• 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

TAXUS PERSEUS Small Vessel is recorded as a completed Phase 3, prospective, non-randomized, single-group trial with no masking. The planned enrollment was 224. It evaluated percutaneous coronary intervention with the TAXUS Element paclitaxel-eluting coronary stent system for de novo atherosclerotic lesions in native coronary arteries, described as up to 20 mm long and in vessels at least 2.25 mm and less than 2.75 mm in diameter.

The primary endpoint was mean in-stent late loss measured by quantitative coronary angiography at 9 months. Target lesion failure at 12 months was listed as a secondary outcome. The primary analysis population was defined as patients with an implanted study device who completed angiographic follow-up.

The registry record does not report the numerical primary or secondary outcome results. It includes descriptive adverse-event figures and historical bare metal stent safety summaries, while warning that the groups are not like-for-like. These data do not provide a randomized comparative estimate.