Safety and Effectiveness Evaluation of Peripheral Orbital Atherectomy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Effectiveness Evaluation of Peripheral Orbital Atherectomy (NCT05529472), a na na study. The primary outcome is Percentage of Subjects With Acute Device Success.

2. Clinical Question

The study is titled KAIZEN and is registered as a prospective, multicenter evaluation of peripheral OAS safety and effectiveness. Its stated objective is to collect data to support potential commercialization of the device in Japan. The registry record lists Peripheral Artery Disease as the condition and identifies Abbott Medical Devices as the sponsor.

The record gives an enrollment of 81. That is a registry enrollment figure, not a reported count for the primary analysis population. The record does not provide the number of participants included in the primary endpoint analysis or the observed percentage meeting acute device success. Those results are not reported in the registry record.

3. Trial Design

This is a prospective, single-arm, multicenter study with no masking. The allocation entry is listed as not applicable, consistent with the single-group model rather than a randomized assignment between treatments. The study is marked completed. The record lists a start date of 2023-01-10 and a primary completion date of 2024-04-01.

The intervention is a treatment regimen involving the Peripheral Orbital Atherectomy System, balloon angioplasty pre-dilation, and a drug-coated balloon. The intended population is Japanese adults with a new symptomatic calcified occlusive atherosclerotic lesion in the superficial femoral artery and/or popliteal artery. The description states that these lesions would otherwise be ineligible for endovascular therapy because of complication risk.

Without a concurrent control group, the design can describe outcomes among participants receiving the study regimen, but it cannot estimate a treatment contrast against another strategy. Any changes or event frequencies observed in this cohort could reflect the treatment, participant characteristics, procedural care, measurement, or other influences; the design alone cannot separate these explanations.

The registry record lists 81 enrolled participants and identifies an analysis cohort and a roll-in cohort in the safety information. It does not describe the allocation procedure or give details about how participants entered those cohorts. The cohort labels should not be interpreted as randomized treatment arms or as a like-for-like comparison. The record also does not report the statistical plan, sample-size justification, or criteria for any interim analyses.

The primary endpoint is assessed at the end of the procedure, while listed secondary outcomes include lesion stenosis, technical and procedural success, patency, angiographic complications, major adverse events, and change in Rutherford classification. The registry record lists 11 outcome measures but no reported analyses. It therefore does not establish whether all planned outcomes were measured or analyzed, or how the listed outcome measures relate to the full study protocol.

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: The 14 subjects enrolled in a roll-in cohort, were conducted as part of the site initiation phase to allow operating investigators for procedural training with the investigational device. These roll-in subjects were not included in the Full Analysis Set (FAS) and were not part of the reported results in Participant Flow, Baseline Characteristics, Outcome Measures, or Adverse Events modules, as predefined in the statistical analysis plan.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The mITT population set included all enrolled subjects who have been treated with the OAD on a target lesion that has met Independent Physician Review, regardless of deviations from the protocol.

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Percentage of Subjects With Acute Device Success, measured over At the end of the procedure.

The primary endpoint is the percentage of participants with acute device success at the end of the procedure. Success requires both residual stenosis of 50% or less after OAD plus POBA, assessed by an angiographic core laboratory, and absence of an OAS-related severe angiographic complication requiring additional treatment during the procedure. The specified complications are severe dissections classified D-F, perforation, or distal emboli, with the complication assessment adjudicated by a clinical events committee.

This is a composite endpoint: both the angiographic result and the procedural safety condition must be met for a participant to count as a success. A participant who meets one component but not the other does not meet the complete definition. Reporting the components separately would help readers understand which part of the definition shaped the overall result, but component results are not reported in the registry record.

Technical success endpoints are used to summarize whether a procedure achieves prespecified procedural goals. They can be useful for describing immediate device and procedure performance, but they do not by themselves establish longer-term benefit. This endpoint is assessed at the end of the procedure, so it does not directly describe later vessel patency, subsequent clinical events, or durability. The registry lists those as separate secondary outcomes.

The endpoint’s denominator is described as the modified intention-to-treat population: enrolled participants treated with OAD on a target lesion meeting Independent Physician Review, regardless of protocol deviations. The number of participants in that population and the observed percentage meeting the endpoint are not reported in the registry record. As a result, the endpoint definition is available, but its estimated rate and precision cannot be assessed from the recorded information.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a single-group design estimate?

In a single-group study, the main descriptive quantity is the outcome frequency among participants who received the intervention and met the analysis definition. For a binary endpoint such as acute device success, each participant is classified as meeting or not meeting the stated criteria. The estimated percentage describes that group under the study’s measurement and analysis rules.

This kind of estimate is not a treatment effect in the comparative sense. A treatment effect usually requires a contrast between outcomes under different assigned strategies. With no concurrent control group, the study cannot estimate a randomized difference between OAS and another treatment. General comparisons with historical or external data would require additional assumptions and are not described in the registry record.

How should a binary endpoint be understood?

A binary outcome has two possible classifications for each participant, such as meeting versus not meeting the endpoint. The primary endpoint is binary because a participant must satisfy both its stenosis criterion and its complication criterion to count as a success. A percentage is the number meeting the definition divided by the analysis population, expressed as a proportion on a percentage scale. The registry record does not report the observed numerator or the primary analysis denominator, so neither the rate nor its uncertainty can be reconstructed from the information recorded.

The endpoint combines clinical and measurement processes. Residual stenosis is assessed by an angiographic core laboratory, while severe complications are adjudicated by a clinical events committee. These roles specify who assesses the components, but the record does not provide details about adjudication procedures, reader agreement, or handling of uncertain assessments.

What does a confidence interval contribute?

In general, a confidence interval communicates uncertainty around an estimated quantity under a specified statistical procedure. A narrow interval indicates greater precision than a wide interval, although precision is not the same as freedom from bias. An interval also does not make a single-group design comparative: it can describe uncertainty around a cohort’s success percentage, but cannot supply the missing counterfactual outcome for a control group. No primary confidence interval is reported in the registry record.

Why can event counts and participant counts differ?

In safety reporting, one participant may experience more than one adverse event, while a count of participants affected records whether each person experienced at least one event in a category. These quantities answer different questions. The registry’s safety entries are participant-based counts for serious and other adverse events in the listed cohorts. They should not be read as a count of all separate event episodes. The record does not provide a detailed event-level dataset or explain all coding and attribution rules.

Adverse-event summaries also depend on the observation period, definitions, and ascertainment methods. General interpretation requires knowing which events qualified as serious, how events were attributed to the device or procedure, and how long participants were followed. The record gives some event information and describes severe angiographic complication criteria for the primary endpoint, but broader details about safety follow-up and event ascertainment are not reported in the registry record.

What do the sample-size assumptions mean?

The registry’s planning illustration is described as using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the target effect expressed as a stated fraction of the observed effect. These are assumptions for planning examples, not evidence that the trial itself used those assumptions. The study is single-group, and the registry does not report a sample-size justification or the trial’s own statistical plan.

For a two-arm planning calculation, equal allocation means assigning the same planned number of participants to each arm. A two-sided significance level defines how a test handles departures in either direction under its assumptions. A normal approximation is a mathematical method for estimating uncertainty or planning sample sizes. These general descriptions do not establish that a randomized two-arm study was conducted; no such comparison is described.

A sample-size illustration based on an observed effect is a planning exercise. It is not observed power, and it does not show that the completed study had adequate power for its endpoint. Without the actual numerical illustration and a reported primary estimate, no particular target size or precision can be inferred. The registry record does not describe interim analyses, multiplicity procedures, or a prespecified model for the primary endpoint.

Why do analysis populations matter?

An analysis population determines which participants contribute to an estimate. The primary endpoint definition specifies a modified intention-to-treat population that includes enrolled participants treated with OAD on a target lesion meeting Independent Physician Review, irrespective of protocol deviations. That definition is narrower than enrollment alone and depends on treatment and lesion-review criteria. The record does not report how many participants met those criteria, whether any were excluded, or how missing endpoint assessments were handled.

These distinctions matter because the enrolled cohort, the treated cohort, and the endpoint analysis population need not be identical. A reported count should always be interpreted with its denominator and population definition. Here, the endpoint population is defined, but its size and result are not reported in the registry record. This prevents verification of the endpoint calculation and limits assessment of the result’s precision.

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("Analysis Cohort[Peripheral Orbital Atherectomy Sys")
n      <- c(66)
events <- c(55)
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  Analysis Cohort[Peripheral Orbital Atherectomy Sys  66  55  83.3  72.1  91.4  72.6  90.4  72.5  90.4

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 11 outcome measures, including the primary endpoint and secondary measures of lesion stenosis, technical success, patency, angiographic complications, major adverse events, and Rutherford classification change. Multiple outcomes create a general statistical issue: when many hypotheses are tested, the chance of at least one apparently unusual finding can increase unless the testing strategy accounts for multiplicity. The registry record does not report whether any multiplicity adjustment, hierarchical testing strategy, or other control of multiple comparisons was planned.

The record lists zero reported analyses. It does not provide outcome-specific estimates, confidence intervals, p-values, or a statistical analysis plan. It is therefore not possible to determine which outcomes were analyzed, whether analyses followed prespecified methods, or whether all planned comparisons are represented.

The primary endpoint population is defined as enrolled participants who were treated with OAD on a target lesion meeting Independent Physician Review, regardless of protocol deviations. However, the number included in that population is not reported. The record also does not state how missing angiographic assessments, unavailable committee adjudications, or incomplete follow-up were handled. Missingness can affect an estimate if participants with unavailable outcomes differ from those with recorded outcomes; this is a general concern, not a claim about what occurred in this study.

Nor does the registry record specify whether the primary analysis used an imputation method, a complete-case approach, or another rule for missing values. Without these details and the analysis denominator, readers cannot assess the impact of missing data or reproduce the endpoint estimate. The record’s completed status does not resolve these reporting gaps.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: peripheral artery pseudoaneurysm (14.3%), distal emboli (13.4%), cancer (7.1%), other infection- localized (7.1%), perforation (7.1%).

The registry’s safety entries are separated into an analysis cohort and a roll-in cohort. Serious adverse events affected 27 participants in the analysis cohort, where 67 were at risk, and 5 participants in the roll-in cohort, where 14 were at risk. Other adverse events affected 49 participants in the analysis cohort and 11 in the roll-in cohort. Deaths are listed as 0 in each cohort.

These are participant counts, not necessarily counts of separate event episodes: one participant may have more than one event. The figures should be read within their respective cohort labels and at-risk counts. The roll-in cohort is not a control arm, and the registry record cautions that the cohorts are not a like-for-like comparison. Differences between their counts cannot be interpreted as evidence of a treatment effect or a comparative safety difference.

The listed serious-event terms and percentages are Peripheral artery pseudoaneurysm, 14.3%; Distal Emboli, 13.4%; Cancer, 7.1%; Other infection- Localized, 7.1%; Perforation, 7.1%; and Dissection, 7.1%. The registry record does not specify the denominator or further calculation details for these term percentages. They should not be treated as rates with a known time-at-risk basis from the information recorded.

Safety interpretation also depends on event definitions, attribution, observation time, and completeness of follow-up. Those details are not fully reported in the registry record. The counts describe recorded safety information; they do not by themselves establish the cause of an event or provide a comparison with another treatment.

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

The record establishes that a prospective, multicenter, single-group study of peripheral OAS was completed and that the primary endpoint was defined around immediate procedural success. It also gives a registry enrollment of 81 and lists safety counts for analysis and roll-in cohorts. These details describe the study framework and some recorded safety information.

The record does not report a numeric primary-endpoint result. It therefore does not show what percentage met the acute device success definition or provide an estimate’s precision. The absence of a reported result is not evidence that the endpoint was or was not achieved. Likewise, the safety counts do not show a comparative treatment effect.

Even if a primary success rate were available, an immediate procedural endpoint would answer a limited question. It would describe the proportion meeting specific angiographic and complication criteria at the end of the procedure. It would not, on its own, establish longer-term vessel patency, durable symptom change, or a net benefit compared with another treatment. The registry lists some of these longer-term or separate outcomes, but their results are not reported in the information available.

The single-group design can support description of outcomes within the treated cohort but cannot rule out alternative explanations for those outcomes. There is no concurrent randomized control group against which to estimate what would have happened under another approach. The listed roll-in cohort does not fill that role, and the record cautions against treating the cohorts as a like-for-like comparison.

Accordingly, the registry information supports a careful account of the study design, endpoint definition, and selected safety counts. It does not support a conclusion about comparative effectiveness, the certainty of the primary outcome, or how results might apply beyond the population described. Those judgments would require outcome estimates, analysis details, and context not reported in the registry record.

14. Why This Trial Matters Statistically

This study illustrates why a clearly defined endpoint and a reported estimate are both needed for statistical interpretation. The registry specifies a two-part acute device success definition, including angiographic assessment and adjudicated complications. That gives readers a basis for understanding what the endpoint was intended to capture. But without its observed percentage, numerator, denominator, or confidence interval, the endpoint cannot be evaluated quantitatively.

It also highlights the distinction between a single-group description and a controlled comparison. A cohort’s event rate may be informative about what was recorded among treated participants, but it does not by itself reveal how outcomes compare with an alternative strategy. This distinction is especially important when a registry includes separately labelled cohorts: labels do not create randomization or make groups interchangeable.

The record further demonstrates why analysis populations and denominators matter. The primary endpoint is defined in a modified intention-to-treat population with treatment and lesion-review requirements. Enrollment alone does not identify the denominator for that endpoint. Reporting the population size, outcome count, and uncertainty would allow readers to understand how the estimate was formed and how precisely it was measured.

Finally, multiple listed outcomes and safety categories require careful interpretation. A complete statistical account would connect outcome definitions to the analysis plan, missing-data handling, and any approach to multiple testing. Those details are not reported in the registry record. The study is therefore statistically relevant as an example of how much the design and endpoint definition can establish, and how much remains uncertain when quantitative results and analysis methods are not recorded.

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 most consequential limitation for interpreting effectiveness is that the registry record does not report the numerical primary endpoint result, its analysis denominator, or an uncertainty interval. Although acute device success is defined, the recorded information does not show how often participants met the full composite criterion. The listed secondary outcomes also lack reported results in the information available.

The single-group design has no concurrent control arm. It can describe outcomes in the studied cohort, but cannot isolate the effect of the intervention from other influences or provide a randomized comparison. The roll-in and analysis cohorts are not a like-for-like control comparison, as the registry record cautions.

The registry provides an enrollment figure and an endpoint population definition, but not the number in the primary analysis population, participant flow, or reasons for any exclusions. Missing outcome data and their handling are not reported. This makes it difficult to assess selection into the analysis and the potential influence of unavailable measurements.

The record does not report the trial’s statistical plan, sample-size justification, multiplicity approach, or interim-analysis procedures. It also does not provide full details of safety follow-up, event ascertainment, attribution, or the denominator used for the listed serious-event term percentages. These omissions limit reproducibility and make it harder to assess precision and completeness.

Finally, the population is specifically described as Japanese adults with new symptomatic calcified lesions in the superficial femoral and/or popliteal artery, selected in the context of complication risk with endovascular therapy. The registry information alone does not establish how findings would apply to other patient groups or lesion settings. That limitation is compounded by the absence of reported outcome estimates.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Safety and Effectiveness Evaluation of Peripheral Orbital Atherectomy — NCT05529472.
• Registry record last updated 2025-10-27; status last verified 2025-09.
• Results first posted 2025-10-27.
• 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

KAIZEN is a completed, prospective, multicenter, single-group study of the Peripheral Orbital Atherectomy System in Japanese adults with symptomatic calcified occlusive lesions in the superficial femoral and/or popliteal artery. The registry lists an enrollment of 81 and identifies Abbott Medical Devices as sponsor. The intervention description includes OAS, balloon angioplasty pre-dilation, and a drug-coated balloon.

The primary endpoint is acute device success at the end of the procedure, defined by residual stenosis of 50% or less and no specified OAS-related severe angiographic complication requiring additional treatment. The record lists 11 outcome measures and provides safety counts for analysis and roll-in cohorts, but no analyses are reported. A numeric primary result, its analysis denominator, confidence interval, missing-data approach, and statistical plan are not reported in the registry record.